0001692115-23-000056 | 10-K | XBRL Viewer | Southwest GAS Holdings INC

Revenue

12 Months Ended

Dec. 31, 2022

Revenue from Contract with Customer [Abstract]

Note 3 - Revenue

The following information about the Company’s revenues is presented by segment. Southwest encompasses the natural gas distribution segment, Centuri encompasses the utility infrastructure services segment, and MountainWest, prior to its sale in February 2023, encompassed the pipeline and storage segment.

Natural Gas Distribution Segment:

Southwest recognizes revenue when it satisfies its performance by transferring gas to the customer. Revenues also include the net impacts of margin tracker/decoupling accruals based on criteria in U.S. GAAP for rate-regulated entities associated with alternative revenue programs. Revenues from customer arrangements and from alternative revenue programs are described below.

Southwest acts as an agent for state and local taxing authorities in the collection and remittance of a variety of taxes, including sales and use taxes and surcharges. These taxes are not included in Regulated operations revenues. Management uses the net classification method to report taxes collected from customers to be remitted to governmental authorities.

Southwest generally offers two types of services to its customers: tariff sales and transportation–only service. Tariff sales encompass sales to many types of customers (primarily residential) under various rate schedules, subject to cost-of-service ratemaking, which is based on the rate-regulation of state commissions and the FERC. Southwest provides both the commodity and the related distribution service to nearly all of its approximate 2.2 million customers, and only several hundred customers (who are eligible to secure their own gas) subscribe to transportation-only service. Natural gas is delivered and consumed by the customer simultaneously. The provision of service is represented by the turn of the meter dial and is the primary representation of the satisfaction of performance obligations of Southwest. The amount billable via regulated rates (both volumetric and fixed monthly rates as part of rate design) corresponds to the value to the customer, and management believes that the amount billable (amount Southwest has the right to invoice) is appropriate to utilize for purposes of recognizing revenue. Estimated amounts remaining unbilled since the last meter read date are restricted from being billed due only to the passage of time and therefore are also recognized for service provided through the balance sheet date. While natural gas service is typically recurring, there is generally not a contract term for utility service. Therefore, the contract term is not generally viewed to extend beyond the service provided to date, and customers can generally terminate service at will.

Transportation-only service is also governed by tariff rate provisions. Transportation-only service is generally only available to very large customers under requirements of Southwest’s various tariffs. With this service, customers secure their own gas supply and Southwest provides transportation services to move the customer-supplied gas to the intended location. Southwest concluded that transportation/transmission service is suitable to an “over time” recognition model. Rate structures under Southwest’s regulation for transportation customers include a combination of volumetric charges and monthly “fixed” charges (including charges commonly referred to as capacity charges, demand charges, or reservation charges) as part of the rate design of regulated jurisdictions. These types of fixed charges represent a separate performance obligation associated with standing ready over the period of the month to deliver quantities of gas, regardless of whether the customer takes delivery of any quantity of gas. The performance obligations under these circumstances are satisfied over the course of the month under an output measure of progress based on time, which correlates to the period for which the charges are eligible to be invoiced.

Under its regulation, Southwest enters into negotiated rate contracts for those customers located in proximity to another pipeline, which pose a threat of bypassing its distribution system. Southwest may also enter into similar contracts for customers otherwise able to satisfy their energy needs by means of alternative fuel to natural gas. Less than two dozen customers are party to contracts with rate components subject to negotiation. Many rate provisions and terms of service for these less common types of contracts are also subject to regulatory oversight and tariff provisions. The performance obligations for these customers are satisfied similarly to those for other customers by means of transporting/delivering natural gas to the customer. Many or most of the rate components, and structures, for these types of customers are the same as those for similar customers without negotiated rate components; and the negotiated rates are within the parameters of the tariff guidelines. Furthermore, while some of these contracts include contract periods extending over time, including multiple years, as amounts billable under the contract are based on rates in effect for the customer for service provided to date, no significant financing component is deemed to exist.

As indicated above, revenues also include the net impacts of margin tracker/decoupling accruals. All of Southwest’s service territories have decoupled rate structures (also referred to as alternative revenue programs) that are designed to eliminate the direct link between volumetric sales and revenue, thereby mitigating the impacts of unusual weather variability and conservation on margin. The primary alternative revenue programs involve permissible adjustments for differences between stated tariff benchmarks and amounts billed through revenue from contracts with customers via existing rates. Such adjustments are recognized monthly in revenue and in the associated regulatory asset/liability accounts in advance of rate adjustments intended to collect or return amounts recognized. Revenues recognized for the adjustment to the benchmarks noted are required to be presented separately from revenues from contracts with customers, and as such, are provided below and identified as related to alternative revenue programs (which excludes recoveries from customers).

Southwest’s operating revenues included on the Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below disaggregated by customer type, in addition to other categories of revenue:


	December 31,
(Thousands of dollars)	2022		2021		2020
Residential	$	1,324,794	$	1,035,612	$	958,520
Small commercial	378,520		270,214		221,541
Large commercial	85,234		57,371		44,633
Industrial/other	50,894		42,313		26,242
Transportation	100,642		92,240		88,215
Revenue from contracts with customers	1,940,084		1,497,750		1,339,151
Alternative revenue program revenues (deferrals)	(18,478)		13,181		12,140
Other revenues (a)	13,463		10,859		(706)
Total Regulated operations revenues	$	1,935,069	$	1,521,790	$	1,350,585

(a) Amounts include late fees and other miscellaneous revenues, and may also include the impact of certain regulatory mechanisms, such as cost-of-service components in current customer rates that are expected to be returned to customers in future periods. Also includes the impacts of a temporary pandemic-period moratorium on late fees and disconnection for nonpayment during the majority of 2020 and part of 2021; 2020 also includes amounts related to tax reform savings reserves/adjustments.

Utility Infrastructure Services Segment:

The majority of Centuri contracts are performed under unit-price contracts. Generally, these contracts state prices per unit of installation. Typical installations are accomplished in a few weeks or less. Revenues are recorded as installations are completed. Revenues are recorded for long-term fixed-price contracts in a pattern that reflects the transfer of control of promised goods and services to the customer over time. The amount of revenue recognized on fixed-price contracts is based on costs expended to date relative to anticipated final contract costs (a method of recognition based on inputs). Some unit-price contracts contain caps that if encroached, trigger revenue and loss recognition similar to a fixed-price contract model.

Centuri is required to collect taxes imposed by various governmental agencies on the work performed for its customers. These taxes are not included in Utility infrastructure services revenues. Management uses the net classification method to report taxes collected from customers to be remitted to governmental authorities.

Centuri derives revenue from the installation, replacement, repair, and maintenance of energy distribution systems. Centuri has operations in the U.S. and Canada. The primary focus of Centuri operations is replacement of natural gas distribution pipe and electric service lines, as well as new infrastructure installations. In addition, Centuri performs certain industrial construction activities for various customers and industries. Centuri has two types of agreements with its customers: master services agreements (“MSAs”) and bid contracts. Most of Centuri’s customers supply many of their own materials in order for Centuri to complete its work under the contracts.

An MSA identifies most of the terms describing each party’s rights and obligations that will govern future work authorizations. An MSA is often effective for multiple years. A work authorization is issued by the customer to describe the location, timing, and any additional information necessary to complete the work for the customer. The combination of the MSA and the work authorization determines when a contract exists and revenue recognition may begin. Each work authorization is generally a single performance obligation as Centuri is performing a significant integration service.

A bid contract is typically a one-time agreement for a specific project that has all necessary terms defining each party’s rights and obligations. Each bid contract is evaluated for revenue recognition individually. Control of assets created under bid contracts generally passes to the customer over time. Bid contracts often have a single performance obligation as Centuri is providing a significant integration service.

Centuri’s MSA and bid contracts are characterized as either fixed-price contracts or unit-price contracts for revenue recognition purposes. The cost-to-cost input method is used to measure progress towards the satisfaction of a performance obligation for fixed-price contracts. Input methods result in the recognition of revenue based on the entity’s expended effort toward satisfaction of the performance obligation relative to the total expected effort to satisfy it in full. For unit-price contracts, an output method is used to measure progress towards satisfaction of a performance obligation (based on the completion of each unit that is required under the contract).

Actual revenues and project costs can vary, sometimes substantially, from previous estimates due to changes in a variety of factors, including unforeseen circumstances. These factors, along with other risks inherent in performing fixed-price contracts

may cause actual revenues and gross profit for a project to differ from previous estimates, and could result in reduced profitability or losses on projects. Changes in these factors may result in revisions to costs and earnings, the impacts for which are recognized in the period in which the changes are identified. Once identified, these types of conditions continue to be evaluated for each project throughout the project term, and ongoing revisions in management’s estimates of contract value, cost, and profit are recognized as necessary in the period determined.

Centuri categorizes work performed under MSAs and bid contracts into three primary service types: gas construction, electrical construction, and other construction. Gas construction includes work involving previously existing gas pipelines and the installation of new pipelines or service lines. Electrical construction includes work involving installation and maintenance of transmission and distribution lines, including storm restoration services. Other construction includes all other work and can include industrial and water utility services.

Contracts can have compensation/consideration that is variable. For MSAs, variable consideration is evaluated at the customer level as the terms creating variability in pricing are included within the MSA and are not specific to a work authorization. For multi-year MSAs, variable consideration items are typically determined for each year of the contract and not for the full contract term. For bid contracts, variable consideration is evaluated at the individual contract level. The expected value method or most likely amount method is used based on the nature of the variable consideration. Types of variable consideration include liquidated damages, delay penalties, performance incentives, safety bonuses, payment discounts, and volume rebates. Centuri will typically estimate variable consideration and adjust financial information, as necessary.

Change orders involve the modification in scope, price, or both to the current contract, requiring approval by both parties. The existing terms of the contract continue to be accounted for under the current contract until such time as a change order is approved. Once approved, the change order is either treated as a separate contract or as part of the existing contract, as appropriate under the circumstances. When the scope is agreed upon in the change order but not the price, Centuri estimates the change to the transaction price.

The following tables display Centuri’s revenue from contracts with customers disaggregated by service type and contract type:


	December 31,
(Thousands of dollars)	2022		2021		2020
Service Types:
Gas infrastructure services	$	1,531,818	$	1,302,340	$	1,261,160
Electric power infrastructure services	778,124		525,202		411,826
Other	450,385		331,119		275,302
Total Utility infrastructure services revenues	$	2,760,327	$	2,158,661	$	1,948,288


	December 31,
(Thousands of dollars)	2022		2021		2020
Contract Types:
Master services agreement	$	2,342,220	$	1,652,978	$	1,490,009
Bid contract	418,107		505,683		458,279
Total Utility infrastructure services revenues	$	2,760,327	$	2,158,661	$	1,948,288

Unit-price contracts	$	1,608,131	$	1,369,082	$	1,356,640
Fixed-price contracts	498,039		267,742		157,701
Time and materials contracts	654,157		521,837		433,947
Total Utility infrastructure services revenues	$	2,760,327	$	2,158,661	$	1,948,288

The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract assets), both of which are included within Accounts receivable, net of allowances, and provides information

about amounts billed in excess of revenue earned on contracts (contract liabilities), which are included in Other current liabilities as of December 31, 2022 and 2021 on the Company’s Consolidated Balance Sheets:


	December 31,
(Thousands of dollars)	2022		2021
Contracts receivable, net	$	394,022	$	296,005
Revenue earned on contracts in progress in excess of billings	238,059		214,774
Amounts billed in excess of revenue earned on contracts	35,769		11,860

The revenue earned on contracts in progress in excess of billings (contract asset) primarily relates to Centuri’s rights to consideration for work completed but not billed and/or approved at the reporting date. These contract assets are transferred to contracts receivable when the rights become unconditional. These contract assets are recoverable from Centuri’s customers based upon various measures of performance, including achievement of certain milestones, completion of specified units or completion of a contract. In addition, many of Centuri’s time and materials arrangements are billed in arrears pursuant to contract terms that are standard within the industry, resulting in contract assets and/or unbilled receivables being recorded, as revenue is recognized in advance of billings. Due to the lag in invoicing associated with contractual provisions (or other economic or market conditions that may impact a customer’s business), Centuri’s ability to bill and subsequently collect amounts due may be impacted. These changes may result in the need to record an estimated valuation allowance to adjust contract asset balances to their net realizable value.

The amounts billed in excess of revenue earned (contract liability) primarily relate to the advance consideration received from customers for which work has not yet been completed. The change in this contract liability balance from December 31, 2021 to December 31, 2022 was due to revenue recognized of approximately $11.9 million that was included in this balance as of January 1, 2022, after which time it became earned and the balance was reduced, in addition to increases due to amounts received, net of revenue recognized during the period related to contracts that commenced during the period.

For contracts that have an original duration of one year or less, Centuri does not consider/compute an interest component based on the time value of money. Further, because of the short duration of these contracts, the Company has not disclosed the transaction price for the remaining performance obligations as of the end of each reporting period or when the Company expects to recognize the revenue.

As of December 31, 2022, Centuri has 57 contracts with an original duration of more than one year. The aggregate amount of the transaction price allocated to the unsatisfied performance obligations of these contracts as of December 31, 2022 was $440.8 million. Centuri expects to recognize the remaining performance obligations over approximately the next two years; however, the timing of that recognition is largely within the control of the customer, including when the necessary equipment and materials required to complete the work will be provided by the customer.

Utility infrastructure services contracts receivable consists of the following:


	December 31,
(Thousands of dollars)	2022		2021
Billed on completed contracts and contracts in progress	$	395,771	$	292,770
Other receivables	2,569		3,492
Contracts receivable, gross	398,340		296,262
Allowance for doubtful accounts	(4,318)		(257)
Contracts receivable, net	$	394,022	$	296,005

Pipeline and Storage Segment:

MountainWest derives revenue on the basis of services rendered, commodities delivered, or contracts settled and includes amounts yet to be billed to customers. MountainWest generates revenue and earnings from annual reservation payments under firm peaking storage and firm transportation contracts. Straight-fixed-variable rate designs are used to allow for recovery of substantially all fixed costs in demand or reservation charges, thereby reducing the earnings impact of volume changes on gas transportation and storage operations.

MountainWest receives upfront payment for certain storage services it provides to customers, which are considered to be contract liabilities. These payments are amortized to revenue over the term of the contract.

The primary types of sales and service activities reported as revenue from contracts with customers are FERC-regulated gas transportation and storage services, and to a lesser extent, natural gas liquid (“NGL”) revenues consisting primarily of NGL

processing services, and other revenue (consisting of natural gas sales, as well as services related to gathering and processing activities and miscellaneous service revenue).

Transportation and storage contracts are primarily stand-ready service contracts that include fixed reservation and variable usage fees. Fixed fees are recognized ratably over the life of the contract as the stand-ready performance obligations are satisfied, while variable usage fees are recognized when MountainWest has a right to consideration from a customer in an amount that corresponds directly with the value to the customer of the performance obligation completed to date. Substantially all of MountainWest’s revenues are derived from performance obligations satisfied over time, rather than recognized at a single point in time. Payment for most sales and services varies by contract type, but is typically due within a month of billing.

MountainWest typically receives or retains NGLs and natural gas from customers when providing natural gas processing, transportation, or storage services. MountainWest records the fair value of NGLs received as service revenue recognized over time and recognizes revenue from the subsequent sale of the NGLs to customers upon delivery. MountainWest typically retains some natural gas under certain transportation service arrangements, intended to facilitate performance of the service and allow for natural losses that occur. As the intent of the retention amount is to enable fulfillment of the contract rather than to provide compensation for services, the fuel allowance is not included in revenue.

MountainWest Regulated operations revenues on the Consolidated Statements of Income of the Company include revenue from contracts with customers, which is shown below, disaggregated by categories of sales and service activities.


(Thousands of dollars)	December 31, 2022
Regulated gas transportation and storage revenues	$	248,304
NGL revenues	5,983
Other revenues	10,152
Revenue from contracts with customers	264,439
Other revenues	174
Total Regulated operations revenues	$	264,613

MountainWest has certain multi-year contracts with fixed-price performance obligations that were unsatisfied (or partially unsatisfied) at the end of the reporting period, whereby revenue will be earned over time as MountainWest stands ready to provide service. These amounts are not material to the Company’s financial statements overall. MountainWest also has certain contract liabilities related to consideration received from customers with an obligation to transfer goods or services subsequent to the balance sheet date, amounts for which are not material.

- Definition

The entire disclosure of revenue from contract with customer to transfer good or service and to transfer nonfinancial asset. Includes, but is not limited to, disaggregation of revenue, credit loss recognized from contract with customer, judgment and change in judgment related to contract with customer, and asset recognized from cost incurred to obtain or fulfill contract with customer. Excludes insurance and lease contracts.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-URI https://asc.fasb.org/topic&trid=49130388

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 10
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130551-203045

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 13
-Subparagraph (b)(2)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130556-203045

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130554-203045

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 9
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130550-203045

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130554-203045

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130554-203045

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130554-203045

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 15
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130558-203045

Reference 10: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 606
-SubTopic 10
-Section 50
-Paragraph 12
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=126920106&loc=SL49130554-203045

+ Details

Income Taxes

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Income Taxes

Note 12 - Income Taxes

Southwest Gas Holdings, Inc.:

The following is a summary of income (loss) before taxes and noncontrolling interests for domestic and foreign operations:


	Year ended December 31,
(Thousands of dollars)	2022		2021		2020
U.S.	$	(302,581)	$	221,507	$	282,489
Foreign	29,244		25,343		22,249
Total income (loss) before income taxes	$	(273,337)	$	246,850	$	304,738

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Current:
Federal	$	(949)	$	(2,872)	$	6,287
State	7,123		(11,516)		8,617
Foreign	9,089		6,524		4,666
	15,263		(7,864)		19,570
Deferred:
Federal	(76,984)		39,117		44,547
State	(12,828)		8,239		414
Foreign	(1,104)		156		1,222
	(90,916)		47,512		46,183
Total income tax expense (benefit)	$	(75,653)	$	39,648	$	65,753

Deferred income tax expense (benefit) consists of the following significant components:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Deferred federal and state:
Property-related items	$	41,191	$	35,072	$	50,504
Purchased gas cost adjustments	76,306		73,613		(5,726)
Employee benefits	12,223		(1,484)		459
Regulatory adjustments	(15,482)		(10,101)		(9,885)
Deferred payroll taxes	(6,344)		(6,344)		(9,055)
Deferred revenue	5,751		6,021		588
Net operating loss	(120,704)		(64,981)		2,331
Goodwill impairment	(105,507)		—		—
Alternative minimum tax	—		—		4,409
All other deferred	21,669		15,768		12,610
Total deferred federal and state	(90,897)		47,564		46,235
Deferred ITC, net	(19)		(52)		(52)
Total deferred income tax expense (benefit)	$	(90,916)	$	47,512	$	46,183

References above and below to Deferred payroll taxes relate to the employer portion of Social Security tax, for which deferment of remittance was permissible under the Coronavirus Aid, Relief, and Economic Security (“CARES”) Act.

A reconciliation of the U.S. federal statutory rate to the consolidated effective tax rate (and the sources of these differences and the effect of each) are summarized as follows:


	Year Ended December 31,
	2022		2021		2020
U.S. federal statutory income tax rate	21.0	%	21.0	%	21.0	%
Net state taxes	3.2		1.0		3.0
Tax credits	0.2		(0.5)		(0.5)
Company-owned life insurance	(0.8)		(1.1)		(0.8)

Amortization of excess deferred taxes	5.2		(4.3)		(0.8)

All other differences	(1.1)		—		(0.3)
Consolidated effective income tax rate	27.7	%	16.1	%	21.6	%

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2022		2021
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	109,093	$	116,496
Employee benefits	29,307		39,181

Net operating losses	223,557		102,853
Deferred payroll taxes	—		6,344
Lease-related item	19,745		18,462
Goodwill impairment	105,507		—
Other	13,197		12,149
Valuation allowance	(2,197)		(4,902)
	498,209		290,583
Deferred tax liabilities:
Property-related items, including accelerated depreciation	873,328		843,559
Regulatory balancing accounts	154,124		77,818

Debt-related costs	(2,365)		2,277
Intangibles	105,668		97,860
Lease-related item	21,164		17,254
Other	28,275		20,562
	1,180,194		1,059,330
Net noncurrent deferred tax liabilities	$	681,985	$	768,747

Net noncurrent deferred tax liabilities above at December 31, 2022 and 2021 are reflected net of $82,000 and $121,000 of noncurrent deferred tax assets associated with the Company’s Canadian operations, which are shown separately on the Company’s Consolidated Balance Sheets.

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2022		2021
Unrecognized tax benefits at beginning of year	$	2,629	$	1,928
Gross increases – tax positions in prior period	389		442

Gross increases – current period tax positions	54		259
Gross decreases – current period tax positions	—		—
Settlements	—		—
Lapse in statute of limitations	—		—
Unrecognized tax benefits at end of year	$	3,072	$	2,629

Southwest Gas Corporation:

The following is a summary of income before taxes:


	Year ended December 31,
(Thousands of dollars)	2022		2021		2020
Total income before income taxes	$	184,921	$	216,473	$	194,873

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Current:
Federal	$	(78)	$	(3,643)	$	(4,678)
State	7,805		(6,556)		(179)
	7,727		(10,199)		(4,857)
Deferred:
Federal	23,710		36,842		38,561
State	(896)		2,695		2,051
	22,814		39,537		40,612
Total income tax expense	$	30,541	$	29,338	$	35,755

Deferred income tax expense (benefit) consists of the following significant components:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Deferred federal and state:
Property-related items	$	29,633	$	23,077	$	36,029
Purchased gas cost adjustments	76,306		73,613		(5,726)
Employee benefits	5,332		5,508		11,437
Regulatory adjustments	(15,482)		(10,101)		(9,885)
Deferred payroll taxes	(892)		(892)		(1,810)
Alternative minimum tax	—		—		4,409
Net operating loss	(76,080)		(59,119)		—
All other deferred	4,016		7,503		6,210
Total deferred federal and state	22,833		39,589		40,664
Deferred ITC, net	(19)		(52)		(52)
Total deferred income tax expense	$	22,814	$	39,537	$	40,612

A reconciliation of the U.S. federal statutory rate to the consolidated effective tax rate (and the sources of these differences and the effect of each) are summarized as follows:


	Year Ended December 31,
	2022		2021		2020
U.S. federal statutory income tax rate	21.0	%	21.0	%	21.0	%
Net state taxes	1.6		0.3		1.7
Tax credits	(0.3)		(0.6)		(0.7)
Company-owned life insurance	0.6		(0.9)		(1.0)

Amortization of excess deferred taxes	(6.9)		(4.9)		(1.3)
All other differences	0.5		(1.3)		(1.4)
Effective income tax rate	16.5	%	13.6	%	18.3	%

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2022		2021
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	94,273	$	101,133
Employee benefits	(12,604)		(4,671)
Net operating losses	135,200		59,119
Deferred payroll taxes	—		892
Other	2,512		6,777
Valuation allowance	—		(22)
	219,381		163,228
Deferred tax liabilities:
Property-related items, including accelerated depreciation	733,011		703,374
Regulatory balancing accounts	154,124		77,818

Debt-related costs	2,062		2,277
Other	14,132		18,587
	903,329		802,056
Net deferred tax liabilities	$	683,948	$	638,828

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2022		2021
Unrecognized tax benefits at beginning of year	$	2,362	$	1,793
Gross increases – tax positions in prior period	259		310
Gross decreases – tax positions in prior period	—		—
Gross increases – current period tax positions	23		259
Gross decreases – current period tax positions	—		—
Settlements	—		—
Lapse in statute of limitations	—		—
Unrecognized tax benefits at end of year	$	2,644	$	2,362

In assessing whether uncertain tax positions should be recognized in its financial statements, management first determines whether it is more-likely-than-not that a tax position will be sustained upon examination, including resolution of any related appeals or litigation processes, based on the technical merits of the position. In evaluations of whether a tax position has met the more-likely-than-not recognition threshold, management presumes that the position will be examined by the appropriate taxing authority that would have full knowledge of all relevant information. For tax positions that meet the more-likely-than-not recognition threshold, management measures the amount of benefit recognized in the financial statements at the largest amount of benefit that is greater than 50% likely of being realized upon ultimate settlement. Unrecognized tax benefits are recognized in the first financial reporting period in which information becomes available indicating that such benefits will more-likely-than-not be realized. For each reporting period, management applies a consistent methodology to measure unrecognized tax benefits, and all unrecognized tax benefits are reviewed periodically and adjusted as circumstances warrant. Measurement of

unrecognized tax benefits is based on management’s assessment of all relevant information, including prior audit experience, the status of audits, conclusions of tax audits, lapsing of applicable statutes of limitation, identification of new issues, and any administrative guidance or developments.

At December 31, 2022, the total amount of unrecognized tax benefits that, if recognized, would impact the effective tax rate was $3.1 million for the Company and $2.6 million for Southwest. No significant increases or decreases in unrecognized tax benefits are expected within the next 12 months.

The Company and Southwest recognize interest expense and income and penalties related to income tax matters in income tax expense. There was $0, $21,000, and $523,000 of tax-related interest income for 2022, 2021, and 2020, respectively.

The Company’s regulated operations accounting for income taxes is impacted by the FASB’s ASC Topic 980 – Regulated Operations. Reductions in accumulated deferred income tax balances due to the reduction in the corporate income tax rates to 21% under the provisions of the Tax Cuts and Jobs Act (the “TCJA”), enacted in December 2017, may continue to result in a refund of excess deferred taxes to customers, generally through reductions in future rates. The TCJA included provisions that stipulate how these excess deferred taxes may be passed back to customers for certain accelerated tax depreciation benefits. The December 31, 2022 Consolidated Balance Sheets of Southwest and the Company reflect the impact of the TCJA and the remaining unamortized balance of the regulatory liability (including a gross-up), barring further changes to income tax rates. See also Note 5 - Regulatory Assets and Liabilities.

The Company and its subsidiaries file a consolidated federal income tax return in the U.S. and in various states, as well as separate returns in Canada. With few exceptions, the Company is no longer subject to U.S. federal, state and local, or Canadian income tax examinations for years before 2018.

The Company and each of its subsidiaries, including Southwest, participate in a tax sharing agreement to establish the method for allocating tax benefits and losses among members of the consolidated group. The consolidated federal income tax is apportioned among the subsidiaries using a separate return method.

The acquisition of MountainWest by the Company was a taxable transaction for U.S. federal and state income tax purposes. As a result, the Company obtained a step-up in the basis of the assets acquired (as determined for income tax purposes), without succeeding to the holding period, accounting methods, or historical income tax liabilities associated with MountainWest. Accordingly, the deferred income taxes were redetermined on the date of acquisition, December 31, 2021.

At December 31, 2022, the Company has a U.S. federal net operating loss carryforward of $932.8 million. The Company also has general business credits of $4 million, which begin to expire in 2041. The Company has no capital loss carryforwards. At December 31, 2022, the Company has an income tax net operating loss carryforward related to Canadian operations of $21.2 million, which begins to expire in 2034. As of the same date, the Company has $519 million of state net operating loss carryforwards. Depending on the jurisdiction in which the state net operating loss was generated, the carryforwards will begin to expire in 2031.

Management intends to continue to permanently reinvest any future foreign earnings in Canada.

- Definition

The entire disclosure for income taxes. Disclosures may include net deferred tax liability or asset recognized in an enterprise's statement of financial position, net change during the year in the total valuation allowance, approximate tax effect of each type of temporary difference and carryforward that gives rise to a significant portion of deferred tax liabilities and deferred tax assets, utilization of a tax carryback, and tax uncertainties information.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 21
-URI https://asc.fasb.org/extlink&oid=121826272&loc=d3e32857-109319

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SAB Topic 11.C)
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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-Publisher FASB
-Name Accounting Standards Codification
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-Subparagraph (SX 210.4-08(h)(2))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Regulated Operations Plant and Leases

12 Months Ended

Dec. 31, 2022

Regulated Operations [Abstract]

Regulated Operations Plant and Leases

Note 2 - Regulated Operations Plant and Leases

Net Regulated Operations Plant

Major classes of regulated operations plant and their respective balances as of December 31, 2022 and 2021 were as follows:


	December 31,
(Thousands of dollars)	2022		2021		2021
	Southwest Gas Holdings Inc.*				Southwest Gas Corporation
Gas plant:
Storage	$	104,218	$	437,793	$	103,874
Transmission	399,357		1,917,529		397,590
Distribution	8,039,793		7,506,489		7,506,489
General	505,109		530,346		496,643
Software and software-related intangibles	389,496		380,372		380,372
Other	15,934		17,161		16,607
	9,453,907		10,789,690		8,901,575
Less: accumulated depreciation and amortization	(2,674,157)		(3,397,736)		(2,538,508)
Construction work in progress	244,750		202,068		183,485
Net regulated operations plant	$	7,024,500	$	7,594,022	$	6,546,552

*Southwest Gas Holdings, Inc. included the regulated operations plant associated with MountainWest only as of December 31, 2021, given that the MountainWest disposal group was deemed held for sale as of December 31, 2022. Therefore, the balances in the table above for Southwest Gas Holdings, Inc. are the same as for Southwest Gas Corporation as of December 31, 2022.

Regulated operations plant depreciation is computed on the straight-line remaining life method at composite rates considered sufficient to amortize costs over estimated service lives, including components which are intended to compensate for removal costs (net of salvage value), and retirements, based on the processes of regulatory proceedings and related regulatory

commission approvals and/or mandates. In 2022, 2021, and 2020, annual regulated operations depreciation and amortization expense in regard to Southwest averaged 2.7% of the original cost of depreciable and amortizable property. Transmission and distribution plant are associated with the core natural gas delivery infrastructure, and combined, constitute the majority of gas plant. Annual regulated operations depreciation expense for Southwest averaged approximately 2.2% of the original cost of depreciable transmission and distribution plant during the period 2020 through 2022.

Depreciation and amortization expense on gas plant, including intangibles, was as follows:


(Thousands of dollars)	2022		2021		2020
Depreciation and amortization expense	$	243,857	$	230,245	$	215,636

Included in the figures above is amortization of regulated operations intangibles of $21 million, $17.7 million, and $13.7 million for the years ended December 31, 2022, 2021, and 2020, respectively. The amounts above exclude regulatory asset and liability amortization.

Leases

Determinations are made as to whether an arrangement is a lease at inception. ROU assets represent the right to use an underlying asset for the lease term; lease liabilities represent obligations to make lease payments arising from the lease. Operating lease ROU assets and lease liabilities are recognized at the commencement date based on the present value of lease payments over the lease term. When leases do not provide an implicit interest rate, an incremental borrowing rate based on information available at commencement is used in determining the present value of lease payments; an implicit rate, if readily determinable, is used. Lease terms utilized in the computations may include options to extend or terminate the lease when it is reasonably certain that the option will be exercised. When lease agreements include non-lease components, they are included with the lease component and accounted for as a single component, for all asset classes. Southwest and MountainWest have no significant operating, finance, or short-term leases.

Centuri has operating and finance leases for corporate and field offices, construction equipment, and transportation vehicles. Centuri is currently not a lessor in any significant lease arrangements. Centuri’s leases have remaining lease terms of up to 16 years. Some of these include options to extend the leases, generally for optional terms of up to 5 years, and some include options to terminate the leases within 1 year. Centuri’s equipment leases may include variable payment terms in addition to the fixed lease payments if machinery is used in excess of the standard work periods. These variable payments are not probable of occurring under the current operating environment and have not been included in consideration of lease payments. During 2021, the presentation of short-term lease cost changed to include all short-term costs associated with leases with a term of less than one month as compared to the historical presentation of only including short-term lease costs for leases with a duration of over one month and less than one year. The lease costs associated with leases with terms of less than one month were $66.4 million for the year ended December 31, 2020. Due to the seasonality of Centuri’s business, expense for short-term leases will fluctuate throughout the year with higher expense incurred during the warmer months. Short-term leases were not recorded on the balance sheet as permitted under the provisions of Accounting Standards Codification (“ASC”) Topic 842. As of December 31, 2022, Centuri had no executed lease agreements that had not yet commenced.

The components of lease expense for Centuri were as follows:


(Thousands of dollars)	2022		2021		2020
Operating lease cost	$	17,881	$	15,279	$	14,294

Finance lease cost:
Amortization of ROU assets	7,702		2,138		140
Interest on lease liabilities	1,520		278		37
Total finance lease cost	9,222		2,416		177
Short-term lease cost	120,339		103,800		19,806
Total lease cost	$	147,442	$	121,495	$	34,277

Supplemental cash flow information related to Centuri leases for the years ended December 31, 2022, 2021, and 2020 was as follows:


(Thousands of dollars)	2022		2021		2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	16,725	$	14,669	$	12,889
Operating cash flows from finance leases	1,520		278		36
Financing cash flows from finance leases	11,985		3,547		199

ROU assets obtained in exchange for lease obligations:
Operating leases	$	22,653	$	11,597	$	19,372
Finance leases	28,861		3,332		361

Supplemental information related to Centuri leases, including location in the Consolidated Balance Sheets, is as follows:


(Thousands of dollars)	December 31,
	2022			2021
Operating leases:
Other property and investments	$	85,270		$	80,638

Other current liabilities	$	13,863		$	12,185
Other deferred credits and other long-term liabilities	77,119			72,930
Total operating lease liabilities	$	90,982		$	85,115

Finance leases:
Other property and investments	$	51,313		$	30,705

Other current liabilities	$	12,028		$	8,858
Other deferred credits and other long-term liabilities	34,238			20,585
Total finance lease liabilities	$	46,266		$	29,443

Weighted average remaining lease term (in years)
Operating leases	6.66			7.57
Finance leases	4.33			3.92

Weighted average discount rate
Operating leases	4.06		%	3.95		%
Finance leases	3.95		%	2.58		%

The following is a schedule of maturities of Centuri lease liabilities as of December 31, 2022:


(Thousands of dollars)	Operating Leases		Finance Leases
2023	$	17,392	$	13,657
2024	15,267		12,225
2025	12,595		9,852
2026	10,646		7,263
2027	10,146		5,311
Thereafter	43,078		2,374
Total lease payments	109,124		50,682
Less imputed interest	18,142		4,416
Total	$	90,982	$	46,266

Pension and Other Postretirement Benefits - Schedule of Expected Benefit Payments (Details) $ in Millions	Dec. 31, 2022 USD ($)
Pension
Defined Benefit Plan Disclosure [Line Items]
2023	$ 65.0
2024	67.0
2025	68.0
2026	69.0
2027	71.0
2028-2032	377.0
SERP
Defined Benefit Plan Disclosure [Line Items]
2023	3.3
2024	3.3
2025	3.2
2026	3.1
2027	3.1
2028-2032	14.6
PBOP
Defined Benefit Plan Disclosure [Line Items]
2023	5.1
2024	5.2
2025	5.2
2026	5.1
2027	5.2
2028-2032	$ 25.6

Income Taxes - Summary of Income Before Taxes and Noncontrolling Interest for Domestic and Foreign Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Abstract]
U.S.	$ (302,581)	$ 221,507	$ 282,489
Foreign	29,244	25,343	22,249
Income (loss) before income taxes	$ (273,337)	$ 246,850	$ 304,738

- Definition

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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Reference 3: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - Southwest - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Net income (loss)	$ (197,684)	$ 207,202	$ 238,985
Defined benefit pension plans:
Net actuarial gain (loss)	3,099	44,974	(43,730)
Amortization of prior service cost	133	729	878
Amortization of net actuarial loss	26,461	33,894	28,751
Regulatory adjustment	(21,457)	(67,027)	5,650
Net defined benefit pension plans	8,236	12,570	(8,451)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	416	1,652	2,467
Net forward-starting interest rate swaps	416	1,652	2,467
Total other comprehensive income (loss), net of tax	2,519	14,242	(4,271)
Comprehensive income (loss)	(195,165)	221,444	234,714
Southwest Gas Corporation
Net income (loss)	154,380	187,135	159,118
Defined benefit pension plans:
Net actuarial gain (loss)	3,099	44,974	(43,730)
Amortization of prior service cost	133	729	878
Amortization of net actuarial loss	26,461	33,894	28,751
Regulatory adjustment	(21,457)	(67,027)	5,650
Net defined benefit pension plans	8,236	12,570	(8,451)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	416	1,652	2,467
Net forward-starting interest rate swaps	416	1,652	2,467
Total other comprehensive income (loss), net of tax	8,652	14,222	(5,984)
Comprehensive income (loss)	$ 163,032	$ 201,357	$ 153,134

Revenue - Schedule of Regulated Operations Revenues: Pipeline and Storage Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Total Regulated operations revenues	$ 2,199,682	$ 1,521,790	$ 1,350,585
Pipeline and Storage
Segment Reporting Information [Line Items]
Revenue from contracts with customers	264,439
Other revenues	174
Total Regulated operations revenues	264,613
Pipeline and Storage \| Regulated gas transportation and storage revenues
Segment Reporting Information [Line Items]
Revenue from contracts with customers	248,304
Pipeline and Storage \| NGL revenues
Segment Reporting Information [Line Items]
Revenue from contracts with customers	5,983
Pipeline and Storage \| Other revenues
Segment Reporting Information [Line Items]
Revenue from contracts with customers	$ 10,152

- Definition

Amount, excluding tax collected from customer, of revenue from satisfaction of performance obligation by transferring promised good or service to customer. Tax collected from customer is tax assessed by governmental authority that is both imposed on and concurrent with specific revenue-producing transaction, including, but not limited to, sales, use, value added and excise.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
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+ Details

Pension and Other Postretirement Benefits - Schedule of Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	$ (4,079)	$ (59,176)	$ 57,539
Amortization of prior service cost	(175)	(959)	(1,155)
Amortization of net actuarial loss	(34,818)	(44,597)	(37,830)
Prior service cost	0	0	0
Regulatory adjustment	28,232	88,194	(7,435)
Recognized in other comprehensive (income) loss	(10,840)	(16,538)	11,119
Net periodic benefit costs recognized in net income	47,226	57,397	56,291
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	36,386	40,859	67,410
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	11,049	(54,892)	45,665
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	(32,468)	(41,955)	(36,025)
Prior service cost	0	0	0
Regulatory adjustment	19,062	86,196	(3,956)
Recognized in other comprehensive (income) loss	(2,357)	(10,651)	5,684
Net periodic benefit costs recognized in net income	41,671	51,194	50,583
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	39,314	40,543	56,267
SERP
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	(6,133)	(3,245)	7,240
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	(2,350)	(2,642)	(1,805)
Prior service cost	0	0	0
Regulatory adjustment	0	0	0
Recognized in other comprehensive (income) loss	(8,483)	(5,887)	5,435
Net periodic benefit costs recognized in net income	4,215	4,599	3,798
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	(4,268)	(1,288)	9,233
PBOP
Defined Benefit Plan Disclosure [Line Items]
Net actuarial loss (gain)	(8,995)	(1,039)	4,634
Amortization of prior service cost	(175)	(959)	(1,155)
Amortization of net actuarial loss	0	0	0
Prior service cost	0	0	0
Regulatory adjustment	9,170	1,998	(3,479)
Recognized in other comprehensive (income) loss	0	0	0
Net periodic benefit costs recognized in net income	1,340	1,604	1,910
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	$ 1,340	$ 1,604	$ 1,910

Pension and Other Postretirement Benefits - Schedule of Amounts Recognized in Balance Sheet and Income Statement (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Change in plan assets:
Market value of plan assets at beginning of year	$ 1,418,211
Market value of plan assets at end of year	1,068,503	$ 1,418,211
Qualified Retirement Plan
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	1,531,197	1,499,239
Service cost	44,110	41,159	$ 34,299
Interest cost	45,006	40,432	45,555
Actuarial loss (gain)	(399,066)	8,908
Benefits paid	(61,796)	(58,541)
Benefit obligation at end of year (PBO/PBO/APBO)	1,159,451	1,531,197	1,499,239
Change in plan assets:
Market value of plan assets at beginning of year	1,366,043	1,186,433
Actual return on plan assets	(330,203)	136,151
Employer contributions	56,000	102,000
Benefits paid	(61,796)	(58,541)
Market value of plan assets at end of year	1,030,044	1,366,043	1,186,433
Funded status at year end	$ (129,407)	$ (165,154)
Weighted-average assumptions (benefit obligation):
Discount rate	5.25%	3.00%
Weighted-average rate of compensation increase	3.25%	3.25%
SERP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$ 49,530	$ 53,631
Service cost	424	526	389
Interest cost	1,441	1,431	1,604
Actuarial loss (gain)	(6,134)	(3,244)
Benefits paid	(3,164)	(2,814)
Benefit obligation at end of year (PBO/PBO/APBO)	42,097	49,530	53,631
Change in plan assets:
Market value of plan assets at beginning of year	0	0
Actual return on plan assets	0	0
Employer contributions	3,164	2,814
Benefits paid	(3,164)	(2,814)
Market value of plan assets at end of year	0	0	0
Funded status at year end	$ (42,097)	$ (49,530)
Weighted-average assumptions (benefit obligation):
Discount rate	5.25%	3.00%
Weighted-average rate of compensation increase	3.25%	3.25%
PBOP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$ 84,226	$ 82,205
Service cost	1,941	1,691	1,581
Interest cost	2,452	2,193	2,582
Actuarial loss (gain)	(18,260)	3,438
Benefits paid	(4,922)	(5,301)
Benefit obligation at end of year (PBO/PBO/APBO)	65,437	84,226	82,205
Change in plan assets:
Market value of plan assets at beginning of year	52,168	52,286
Actual return on plan assets	(6,036)	7,717
Employer contributions	0	0
Benefits paid	(7,673)	(7,835)
Market value of plan assets at end of year	38,459	52,168	$ 52,286
Funded status at year end	$ (26,978)	$ (32,058)
Weighted-average assumptions (benefit obligation):
Discount rate	5.25%	3.00%

CONSOLIDATED STATEMENTS OF EQUITY - Southwest - USD ($) $ in Thousands	Total	Southwest Gas Corporation	Common stock shares	Common stock shares Southwest Gas Corporation	Additional paid-in capital	Additional paid-in capital Southwest Gas Corporation	Accumulated other comprehensive loss	Accumulated other comprehensive loss Southwest Gas Corporation	Retained earnings	Retained earnings Southwest Gas Corporation
Beginning balance (in shares) at Dec. 31, 2019			55,007,000
Beginning balance at Dec. 31, 2019			$ 56,637		$ 1,466,937	$ 1,229,083	$ (56,732)	$ (55,151)	$ 1,039,072	$ 782,108
Net income									232,324	159,118
Share-based compensation						3,340				(780)
Contributions from Southwest Gas Holdings, Inc.						177,922
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax							(8,451)	(8,451)
FSIRS amounts reclassified to net income, net of tax	$ 2,467	$ 2,467					2,467	2,467
Dividends declared to Southwest Gas Holdings, Inc.									(128,905)	(105,300)
Ending balance (in shares) at Dec. 31, 2020			57,193,000	47,482,000
Ending balance at Dec. 31, 2020		2,233,468	$ 58,823	$ 49,112	1,609,155	1,410,345	(61,003)	(61,135)	1,067,978	835,146
Net income									200,779	187,135
Share-based compensation						5,983				(854)
Contributions from Southwest Gas Holdings, Inc.						202,583
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax							12,570	12,570
FSIRS amounts reclassified to net income, net of tax	$ 1,652	1,652					1,652	1,652
Dividends declared to Southwest Gas Holdings, Inc.									(142,428)	(114,600)
Ending balance (in shares) at Dec. 31, 2021	60,422,081		60,422,000	47,482,000
Ending balance at Dec. 31, 2021		2,527,937	$ 62,052	$ 49,112	1,824,216	1,618,911	(46,761)	(46,913)	1,114,313	906,827
Net income									(203,290)	154,380
Share-based compensation						4,058				(852)
Contributions from Southwest Gas Holdings, Inc.						0
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax							8,236	8,236
FSIRS amounts reclassified to net income, net of tax	$ 416	416					416	416
Dividends declared to Southwest Gas Holdings, Inc.									(167,279)	(125,000)
Ending balance (in shares) at Dec. 31, 2022	67,119,143		67,119,000	47,482,000
Ending balance at Dec. 31, 2022		$ 2,569,175	$ 68,749	$ 49,112	$ 2,287,183	$ 1,622,969	$ (44,242)	$ (38,261)	$ 747,069	$ 935,355

- Definition

Amount of stockholders' equity (deficit), net of receivables from officers, directors, owners, and affiliates of the entity, attributable to both the parent and noncontrolling interests. Amount excludes temporary equity. Alternate caption for the concept is permanent equity.

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+ Details

Regulated Operations Plant and Leases - Supplemental Information Related to Leases Included in Balance Sheet (Details) - Centuri - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Lessee, Lease, Description [Line Items]
Operating lease ROU assets	$ 85,270	$ 80,638
Operating leases, other current liabilities	13,863	12,185
Operating lease, other deferred credits and other long-term liabilities	77,119	72,930
Total operating lease liabilities	90,982	85,115
Finance lease, other property and investments	51,313	30,705
Finance lease, other current liabilities	12,028	8,858
Finance lease, other deferred credits and other long-term liabilities	34,238	20,585
Total finance lease liabilities	$ 46,266	$ 29,443
Operating lease, weighted average remaining lease term (in years)	6 years 7 months 28 days	7 years 6 months 25 days
Finance lease, weighted average remaining lease term (in years)	4 years 3 months 29 days	3 years 11 months 1 day
Operating lease, weighted average discount rate	4.06%	3.95%
Finance lease, weighted average discount rate	3.95%	2.58%

Segment Information

12 Months Ended

Dec. 31, 2022

Segment Reporting [Abstract]

Segment Information

Note 13 - Segment Information

The Company’s operating segments are determined based on the nature of their activities. The natural gas distribution segment is engaged in the business of purchasing, distributing, and transporting natural gas. The utility infrastructure services segment is primarily engaged in the business of providing gas and electric providers installation, replacement, repair, and maintenance of energy networks. Although the utility infrastructure services operations are geographically dispersed, they are aggregated and reported as a single segment as each reporting unit has similar economic characteristics. Over 99% of the total Company’s long-lived assets are in the U.S. The pipeline and storage segment (sold in 2023) is primarily engaged in the business of providing interstate transportation and underground storage services, primarily composed of regulated operations under the jurisdiction of the FERC.

The accounting policies of the reported segments are the same as those described within Note 1 - Background, Organization, and Summary of Significant Accounting Policies. Centuri accounts for the services provided to Southwest at contractual prices at contract inception. Accounts receivable for these services, which are not eliminated during consolidation, are presented in the table below:


	December 31,
(Thousands of dollars)	2022		2021
Accounts receivable for Centuri services	$	18,067	$	15,166

The following table presents the amount of revenues by geographic area:


	December 31,
(Thousands of dollars)	2022		2021		2020
Revenues (a)
United States	$	4,637,557	$	3,411,018	$	3,057,041
Canada	322,452		269,433		241,832
Total	$	4,960,009	$	3,680,451	$	3,298,873

(a)Revenues are attributed to countries based on the location of customers.

The Company has three reportable segments beginning in 2021: natural gas distribution, utility infrastructure services, and pipeline and storage. In order to reconcile to net income as disclosed in the Consolidated Statements of Income, an Other column is included associated with impacts of corporate and administrative activities related to Southwest Gas Holdings, Inc. The financial information pertaining to each segment as of and for the three years ended December 31, 2022, 2021, and 2020 are as follows:


	Year Ended December 31, 2022
(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Pipeline and Storage		Other		Total
Revenues from external customers	$	1,935,069	$	2,625,669	$	264,613	$	—	$	4,825,351
Intersegment sales	—		134,658		—		—		134,658
Total	$	1,935,069	$	2,760,327	$	264,613	$	—	$	4,960,009
Interest income	$	16,183	$	—	$	—	$	—	$	16,183
Interest expense	$	115,880	$	61,371	$	18,185	$	47,314	$	242,750
Depreciation and amortization	$	263,043	$	155,353	$	52,059	$	—	$	470,455
Income tax expense (benefit)	$	30,541	$	5,727	$	(89,668)	$	(22,253)	$	(75,653)
Segment net income (loss)	$	154,380	$	2,065	$	(283,733)	$	(76,002)	$	(203,290)
Segment assets*	$	8,803,681	$	2,642,272	$	1,743,349	$	7,312	$	13,196,614
Capital expenditures	$	683,131	$	130,166	$	46,124	$	—	$	859,421

*The segment assets of the Pipeline and Storage segment represented by MountainWest have been reclassified, as of December 31, 2022, as current assets held for sale on the Company’s Consolidated Balance Sheet. See Note 15 - Acquisitions and Dispositions for additional information.


	Year Ended December 31, 2021
(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Pipeline and Storage		Other		Total
Revenues from external customers	$	1,521,790	$	2,056,315	$	—	$	—	$	3,578,105
Intersegment sales	—		102,346		—		—		102,346
Total	$	1,521,790	$	2,158,661	$	—	$	—	$	3,680,451
Interest income	$	5,113	$	—	$	—	$	—	$	5,113
Interest expense	$	97,560	$	20,999	$	—	$	639	$	119,198
Depreciation and amortization	$	253,398	$	117,643	$	—	$	—	$	371,041
Income tax expense	$	29,338	$	18,776	$	—	$	(8,466)	$	39,648
Segment net income (loss)	$	187,135	$	40,420	$	—	$	(26,776)	$	200,779
Segment assets	$	7,950,263	$	2,579,748	$	2,187,582	$	47,664	$	12,765,257
Capital expenditures	$	601,983	$	113,643	$	—	$	—	$	715,626


	Year Ended December 31, 2020
(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Other		Total
Revenues from external customers	$	1,350,585	$	1,813,429	$	—	$	3,164,014
Intersegment sales	—		134,859		—		134,859
Total	$	1,350,585	$	1,948,288	$	—	$	3,298,873
Interest income	$	4,015	$	—	$	—	$	4,015
Interest expense	$	101,148	$	9,269	$	1,060	$	111,477
Depreciation and amortization	$	235,295	$	96,732	$	—	$	332,027
Income tax expense	$	35,755	$	31,128	$	(1,130)	$	65,753
Segment net income (loss)	$	159,118	$	74,862	$	(1,656)	$	232,324
Segment assets	$	7,256,636	$	1,475,237	$	3,980	$	8,735,853
Capital expenditures	$	692,216	$	132,889	$	—	$	825,105

The corporate and administrative activities for Southwest Gas Holdings, Inc. in 2022 and 2021 include expenses incurred to acquire MountainWest (2021 only), as well as shareholder activism costs, costs related to the strategic review, the settlement agreement with the Icahn Group, and the most significant individual amount being the financing costs for the MountainWest acquisition in 2022, collectively net of tax impacts.

- Definition

The entire disclosure for reporting segments including data and tables. Reportable segments include those that meet any of the following quantitative thresholds a) it's reported revenue, including sales to external customers and intersegment sales or transfers is 10 percent or more of the combined revenue, internal and external, of all operating segments b) the absolute amount of its reported profit or loss is 10 percent or more of the greater, in absolute amount of 1) the combined reported profit of all operating segments that did not report a loss or 2) the combined reported loss of all operating segments that did report a loss c) its assets are 10 percent or more of the combined assets of all operating segments.

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+ Details

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Estimated Future Amortization of Intangible Assets (Details) - Centuri - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
2023	$ 26,690
2024	26,690
2025	26,678
2026	26,455
2027	26,088
Thereafter	262,647
Net Carrying Amount	$ 395,248	$ 426,505

Debt

12 Months Ended

Dec. 31, 2022

Debt Disclosure [Abstract]

Debt

Note 8 - Debt

Long-Term Debt

Long-term debt is recognized in the Company’s and Southwest’s Consolidated Balance Sheets generally at the carrying value of the obligations outstanding. Details surrounding the fair value and individual carrying values of instruments are provided in the table that follows.


	December 31,
	2022				2021
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
(Thousands of dollars)
Southwest Gas Corporation:
Debentures:
Notes, 6.1%, due 2041	$	125,000	$	113,184	$	125,000	$	166,380
Notes, 4.05%, due 2032	600,000		527,052		—		—
Notes, 3.875%, due 2022	—		—		250,000		250,603
Notes, 4.875%, due 2043	250,000		195,703		250,000		307,538
Notes, 3.8%, due 2046	300,000		209,169		300,000		329,055
Notes, 3.7%, due 2028	300,000		275,043		300,000		325,191
Notes, 4.15%, due 2049	300,000		218,712		300,000		342,030
Notes, 2.2%, due 2030	450,000		353,763		450,000		440,838
Notes, 3.18%, due 2051	300,000		185,523		300,000		292,116
Notes, 5.8%, due 2027	300,000		305,913		—		—
8% Series, due 2026	75,000		80,027		75,000		92,623
Medium-term notes, 7.78% series, due 2022	—		—		25,000		25,122
Medium-term notes, 7.92% series, due 2027	25,000		26,840		25,000		31,555
Medium-term notes, 6.76% series, due 2027	7,500		7,662		7,500		8,949
Unamortized discount and debt issuance costs	(29,471)				(19,959)
	3,003,029				2,387,541
Revolving credit facility and commercial paper	50,000		50,000		130,000		130,000
Industrial development revenue bonds:
Tax-exempt Series A, due 2028	50,000		50,000		50,000		50,000
2003 Series A, due 2038	50,000		50,000		50,000		50,000
2008 Series A, due 2038	50,000		50,000		50,000		50,000
2009 Series A, due 2039	50,000		50,000		50,000		50,000
Unamortized discount and debt issuance costs	(1,733)				(1,938)
	198,267				198,062
Less: current maturities	—				(275,000)
Southwest Gas Corporation total long-term debt, less current maturities	$	3,251,296			$	2,440,603


Southwest Gas Holdings, Inc.:
Centuri secured term loan facility	$	1,008,550	$	995,852	$	1,117,138	$	1,117,841
Centuri secured revolving credit facility	81,955		82,315		103,329		103,749
MountainWest unsecured senior notes, 3.53%, due in 2028*	—		—		102,078		102,078
MountainWest unsecured senior notes, 4.875%, due in 2041*	—		—		199,926		199,926
MountainWest unsecured senior notes, 3.91%, due in 2038*	—		—		147,735		147,735
Other debt obligations	126,844		118,314		51,665		50,003
Unamortized discount and debt issuance costs	(20,789)				(24,466)
Less: current maturities	(44,557)				(22,324)
Southwest Gas Holdings, Inc. total long-term debt, less current maturities	$	4,403,299			$	4,115,684

*MountainWest amounts are not reflected in the above table as of December 31, 2022 as the balance has been reclassified as held for sale on the Company’s Consolidated Balance Sheet as of December 31, 2022. See Note 15 - Acquisitions and Dispositions for additional information.

The fair values of Southwest's and the Company’s revolving credit facilities and Southwest’s Industrial Development Revenue Bonds (“IDRBs”) are categorized as Level 1 based on the FASB’s fair value hierarchy, due to the ability to access similar debt arrangements at measurement dates with comparable terms, including variable/market rates. Additionally, Southwest’s revolving credit facility and IDRBs have interest rates that reset frequently. The fair values of Southwest’s debentures (which include senior and medium-term notes) and the Company's term loan facility and unsecured senior notes were determined utilizing a market-based valuation approach, where fair values are determined based on evaluated pricing data, and as such are categorized as Level 2 in the hierarchy.

Southwest has a $400 million credit facility that is scheduled to expire in April 2025. Southwest designates $150 million of associated capacity as long-term debt and the remaining $250 million for working capital purposes. Interest rates for the credit facility are calculated at either the Secured Overnight Financing Rate (“SOFR”) or an “alternate base rate,” plus in each case an applicable margin that is determined based on Southwest’s senior unsecured debt rating. At December 31, 2022, the applicable margin ranges from 0.750% to 1.500% for loans bearing interest with reference to SOFR and from 0.000% to 0.500% for loans bearing interest with reference to the alternative base rate. At December 31, 2022, the applicable margin is 1.125% for loans with reference to SOFR and 0.125% for loans bearing interest with reference to the alternative base rate. Southwest is also required to pay a commitment fee, ranging from 0.075% to 0.200% per annum, on the unfunded portion of the commitments, which was not significant for the year ended December 31, 2022. The credit facility contains a financial covenant requiring Southwest to maintain a ratio of funded debt to total capitalization not to exceed 0.70 to 1.00 as of the end of any quarter of any fiscal year. At December 31, 2022, $50 million was outstanding on the long-term portion (no borrowings were outstanding under the commercial paper program discussed below). The effective interest rate on the long-term portion of the credit facility was 5.88% at December 31, 2022.

Southwest has a $50 million commercial paper program. Issuances under the commercial paper program are supported by Southwest’s current revolving credit facility and, therefore, do not represent additional borrowing capacity. Borrowings under the commercial paper program, if any, are designated as long-term debt. Interest rates for the program are calculated at the then current commercial paper rate. At December 31, 2022, as noted above, no borrowings were outstanding under the commercial paper program.

In March 2022, Southwest issued $600 million aggregate principal amount of 4.05% Senior Notes at a discount of 0.65%. The notes will mature in March 2032. Southwest used the net proceeds to redeem the $250 million 3.875% notes due in April 2022 and to repay outstanding amounts under its credit facility, with the remaining net proceeds used for general corporate purposes.

Centuri has a $1.545 billion secured revolving credit and term loan multi-currency facility. Amounts can be borrowed in either Canadian or U.S. dollars. On November 4, 2022, Centuri amended the financial covenants of its revolving credit facility to increase the maximum total net leverage ratio during the period from December 31, 2022 through December 31, 2023 (the “Centuri Credit Facility Amendment”). The Centuri Credit Facility Amendment also transitioned the interest rate benchmark for the revolving credit facility from LIBOR to SOFR. The applicable margin for the revolving credit facility now ranges from 1.0% to 2.5% for SOFR loans and from 0.0% to 1.5% for Canadian Dealer Offered Rate (“CDOR”) and “base rate” loans, depending on Centuri’s total net leverage ratio. Further, the Centuri Credit Facility Amendment increases a letter of credit sub-facility from $100 million to $125 million. The Centuri Credit Facility Amendment did not modify any terms of the term loan facility. The revolving credit facility matures on August 27, 2026 and the term loan facility matures on August 27, 2028. The capacity of the line of credit portion of the facility is $400 million; related amounts borrowed and repaid are available to be re-borrowed. The term loan portion of the facility has a limit of $1.145 billion. The obligations under the credit agreement are

secured by present and future ownership interests in substantially all direct and indirect subsidiaries of Centuri, substantially all of the tangible and intangible personal property of each borrower, certain of their direct and indirect subsidiaries, and all products, profits, and proceeds of the foregoing.

The term loan facility is subject to a LIBOR floor of 0.50%. Furthermore, Centuri Canada Division Inc. may borrow under the revolving credit facility with interest rates based on terms referred to above. The margin for the term loan facility is 1.50% for base rate loans and 2.50% for LIBOR loans. Centuri is also required to pay a commitment fee on the unused portion of the commitments. The commitment fee ranges from 0.15% to 0.35% per annum. The credit agreement contains certain customary representations and warranties, affirmative and negative covenants, and events of default. There are no financial covenants related to the term loan facility. The revolving credit facility requires Centuri to maintain a maximum total net leverage ratio of 6.00 to 1.00 from December 31, 2022 through June 30, 2023, 5.50 to 1.00 from July 1, 2023 through September 30, 2023, 4.50 to 1.00 from October 1, 2023 through December 31, 2023, and 4.00 to 1.00 from January 1, 2024 and thereafter. The agreement also requires Centuri to maintain a minimum interest coverage ratio of 2.50 to 1.00. Centuri’s assets securing the facility at December 31, 2022 totaled $2.5 billion. At December 31, 2022, $1.091 billion in borrowings were outstanding under Centuri’s combined secured revolving credit and term loan facility.

All amounts outstanding are considered long-term borrowings. The effective interest rate on the secured revolving credit and term loan facility was 7.2% at December 31, 2022.

The effective interest rates on Southwest’s variable-rate IDRBs are included in the table below:


	December 31,
	2022		2021
2003 Series A	4.68	%	0.91	%
2008 Series A	4.84	%	0.90	%
2009 Series A	4.67	%	0.88	%
Tax-exempt Series A	4.30	%	0.92	%

In Nevada, interest fluctuations due to changing interest rates on Southwest’s 2003 Series A, 2008 Series A, and 2009 Series A variable-rate IDRBs are tracked and recovered from customers through a variable interest expense recovery mechanism.

None of Southwest’s debt instruments have credit triggers or other clauses that result in default if bond ratings are lowered by rating agencies. Interest and fees on certain debt instruments are subject to adjustment depending on Southwest’s bond ratings. Certain debt instruments are subject to a leverage ratio cap and the 6.1% Notes due 2041 are also subject to a minimum net worth requirement. At December 31, 2022, Southwest was in compliance with all of its covenants. Under the most restrictive of the financial covenants, approximately $2.5 billion in additional debt could be issued while still meeting the leverage ratio requirement. Relating to the minimum net worth requirement, as of December 31, 2022, there is at least $2 billion of cushion in equity. No specific dividend restrictions exist under the collective covenants. None of the debt instruments contain material adverse change clauses.

Certain Centuri debt instruments have leverage ratio caps and fixed charge ratio coverage requirements. At December 31, 2022, Centuri was in compliance with all of its covenants. Under the most restrictive of the covenants, Centuri could issue over $222 million in additional debt and meet the leverage ratio requirement. Centuri has at least $33 million of cushion relating to the minimum fixed charge ratio coverage requirement. Centuri’s covenants limit its ability to provide cash dividends to Southwest Gas Holdings, Inc., its parent. The dividend restriction is equal to a calculated available amount generally defined as 50% of its rolling twelve-month consolidated net income adjusted for certain items, such as parent contribution inflows, Linetec redeemable noncontrolling interest payments, or dividend payments, among other adjustments, as applicable.

Estimated maturities of long-term debt for the next five years are:


(Thousands of dollars)	2023		2024		2025		2026		2027		Total
Southwest Gas Corporation:
Debentures	$	—	$	—	$	—	$	75,000	$	332,500	$	407,500
Revolving credit facility and commercial paper	—		—		50,000		—		—		50,000
Total	—		—		50,000		75,000		332,500		457,500
Southwest Gas Holdings, Inc.:
Centuri secured term loan facility	14,313		11,450		11,450		11,450		11,450		60,113
Centuri secured revolving credit facility	—		—		—		81,955		—		81,955
Other debt obligations	30,245		31,102		29,554		28,651		7,292		126,844
Total	$	44,558	$	42,552	$	91,004	$	197,056	$	351,242	$	726,412

Short-Term Debt

Southwest Gas Holdings, Inc. has a $300 million credit facility that is primarily used for short-term financing needs. Interest rates for this facility are calculated at either SOFR or the “alternate base rate,” plus in each case an applicable margin that is determined based on the Company’s senior unsecured debt rating. There was $173 million and $59 million outstanding under this facility with a weighted average interest rate of 5.588% and 1.323% at December 31, 2022 and 2021, respectively.

On December 30, 2022, in connection with that certain Amended and Restated Revolving Credit Agreement, dated as of April 10, 2020 (as amended by Amendment No. 1 thereto, dated as of December 28, 2021), by and between Southwest Gas Holdings, Inc., the lenders party thereto, and The Bank of New York Mellon, as Administrative Agent, and pursuant to an Increase Request delivered by the Company to the Administrative Agent, the total commitment amount available under the credit facility was increased, from $200 million to $300 million. Interest rate benchmarks (SOFR or an alternative) as well as related ranges, including with regard to the applicable margin, largely mirror those included in Southwest’s amended facility agreement noted above, determined in this case based on Southwest Gas Holdings, Inc.’s senior unsecured long-term debt rating. At December 31, 2022, the applicable margin is 1.250% for loans bearing interest with reference to SOFR and 0.250% for loans bearing interest with reference to the alternative base rate. The commitment fee rates, terms, and covenants, noted above for Southwest, are also applicable to Southwest Gas Holdings, Inc. in its amended credit facility, including the noted ratio of funded debt to total capitalization as of the end of any quarter of any fiscal year. The commitment fee under this credit facility was not significant for the year ended December 31, 2022.

In March 2022, Southwest amended its $250 million Term Loan (the “March 2021 Term Loan”) extending the maturity date to March 21, 2023 and replacing LIBOR interest rate benchmarks with SOFR interest rate benchmarks. The proceeds were originally used to fund the increased cost of natural gas supply during the month of February 2021, caused by extreme weather conditions in the central U.S. There was $225 million outstanding under the March 2021 Term Loan as of December 31, 2022. Interest rates for the amended term loan are calculated at either SOFR or an “alternate base rate,” plus in each case an applicable margin that is determined based on Southwest’s senior unsecured long-term debt rating. The applicable margin ranges from 0.550% to 1.000% for loans bearing interest with reference to SOFR and 0.000% for loans bearing interest with reference to an alternate base rate. The amended agreement contains a financial covenant requiring Southwest to maintain a ratio of funded debt to total capitalization not to exceed 0.70 to 1.00 as of the end of any quarter of any fiscal year. The weighted average interest rate at December 31, 2022 was 5.173%.

On September 26, 2022, Southwest Gas Holdings, Inc. entered into Amendment No. 1 to the 364-day Term Loan Credit Agreement. The Credit Agreement provided for a $1.6 billion delayed-draw term loan (the “Term Loan Facility”) to primarily fund the acquisition of the equity interests in MountainWest. The amended Credit Agreement, among other things, (1) extended the maturity date of the Term Loan to December 30, 2023 and (2) replaced LIBOR benchmarks with SOFR interest rate benchmarks. The Company agreed to pay the Lenders fees equal to 0.10% of the aggregate principal amount outstanding under the Term Loan on March 31, 2023, 0.15% of the aggregate principal amount outstanding under the Term Loan on June 30, 2023, and 0.20% of the aggregate principal amount outstanding under the Term Loan on September 30, 2023. There was $1.15 billion outstanding under the Term Loan Facility as of December 31, 2022. Upon the close of the MountainWest sale, the Company paid down $1.075 billion of the Term Loan Facility, leaving approximately $72 million in aggregate principal amount outstanding. The applicable margin for the Term Loan Facility is 0.500% to 1.250% for base rate loans and 1.500% to 2.250% for SOFR loans, depending on the applicable pricing level in effect. Each of the interest rate spreads will increase by 0.25% at certain time intervals beginning June 30, 2023. The commitment fee ranges from 0.060% to 0.175% per calendar quarter commencing January 3, 2022, depending on the applicable pricing level in effect. The pricing levels are based on the

Company’s senior debt ratings. The interest rate is subject to customary benchmark replacement provisions. The weighted average interest rate at December 31, 2022 was 6.423%.

The Credit Agreement contains representations and warranties, affirmative, negative, and financial covenants and events of default substantially similar to the Company’s existing credit facility. Subject to certain exceptions, after the funding date, the Company must make a mandatory prepayment from 100% of the net cash proceeds received by the Company or any of its subsidiaries from any debt offerings or equity issuances and/or 100% of the committed amount under any specified acquisition financings.

At December 31, 2022, Southwest Gas Holdings, Inc. was in compliance with all of its credit facility and 364-day Term Loan covenants. Interest and fees on the credit facility and 364-day Term Loan are subject to adjustment depending on its senior debt ratings. The credit facility and 364-day Term Loan are subject to a leverage ratio cap. Under the most restrictive of the financial covenants, approximately $1.2 billion in additional debt could be issued while still meeting the leverage ratio requirement. No specific dividend restrictions exist under the collective covenants. The credit facility and 364-day Term Loan do not contain material adverse change clauses.

As indicated above, under Southwest’s $400 million credit facility, $250 million has been designated by management for working capital purposes. Southwest had no short-term borrowings outstanding at December 31, 2022 and 2021.

In January 2023, Southwest entered into a 364-day $450 million term loan agreement that matures on January 19, 2024. The Company used the proceeds to fund higher than expected natural gas costs for the November 2022 through March 2023 winter period, caused by numerous market forces including historically low storage levels, unexpected upstream pipeline maintenance events, and cold weather conditions across the western region. Interest rates for this term loan are calculated at either SOFR plus an adjustment of 0.100% or an “alternate base rate,” plus in each case an applicable margin that is determined based on Southwest’s senior unsecured long-term debt rating. The applicable margin is 0.950% with reference to SOFR and 0.000% with reference to the alternate base rate. The term loan agreement contains a financial covenant requiring Southwest to maintain a ratio of funded debt to total capitalization not to exceed 0.70 to 1.00 as of the end of any quarter of any fiscal year.

LIBOR

Certain rates established at LIBOR were scheduled to be discontinued as a benchmark or reference rate after 2021, while other LIBOR-based rates are scheduled to be discontinued after June 2023. As of December 31, 2022, the Company had $1.009 billion in aggregate outstanding borrowings under Centuri’s Term Loan Facility. Southwest and Southwest Gas Holdings, Inc. had no outstanding borrowings or variable rate debt agreements with reference to LIBOR as of December 31, 2022.

- Definition

The entire disclosure for information about short-term and long-term debt arrangements, which includes amounts of borrowings under each line of credit, note payable, commercial paper issue, bonds indenture, debenture issue, own-share lending arrangements and any other contractual agreement to repay funds, and about the underlying arrangements, rationale for a classification as long-term, including repayment terms, interest rates, collateral provided, restrictions on use of assets and activities, whether or not in compliance with debt covenants, and other matters important to users of the financial statements, such as the effects of refinancing and noncompliance with debt covenants.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 470
-URI https://asc.fasb.org/topic&trid=2208564

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
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-Name Accounting Standards Codification
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+ Details

CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Statement of Comprehensive Income [Abstract]
Net income (loss)	$ (197,684)	$ 207,202	$ 238,985
Defined benefit pension plans:
Net actuarial gain (loss)	3,099	44,974	(43,730)
Amortization of prior service cost	133	729	878
Amortization of net actuarial loss	26,461	33,894	28,751
Regulatory adjustment	(21,457)	(67,027)	5,650
Net defined benefit pension plans	8,236	12,570	(8,451)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	416	1,652	2,467
Net forward-starting interest rate swaps	416	1,652	2,467
Foreign currency translation adjustments	(6,133)	20	1,713
Total other comprehensive income (loss), net of tax	2,519	14,242	(4,271)
Comprehensive income (loss)	(195,165)	221,444	234,714
Comprehensive income attributable to noncontrolling interests	5,606	6,423	6,661
Comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	$ (200,771)	$ 215,021	$ 228,053

Common Stock - Activity of Equity Shelf Program (Details) - USD ($)	12 Months Ended			21 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Class of Stock [Line Items]
Net proceeds	$ 461,828,000	$ 213,641,000	$ 139,245,000
Equity Shelf Program
Class of Stock [Line Items]
Gross proceeds				$ 158,180,343
Less: agent commissions				(1,581,803)
Net proceeds				$ 156,598,540
Number of shares sold (in shares)				2,302,407
Weighted average price per share (in USD per share)				$ 68.70

Common Stock - Narrative (Details) - USD ($) $ / shares in Units, shares in Thousands	1 Months Ended		12 Months Ended
	Mar. 31, 2022	Nov. 30, 2021	Dec. 31, 2022	Apr. 08, 2021
Class of Stock [Line Items]
Sale of stock, number of shares (in shares)	6,325
Sale of stock, price per share (in USD per share)	$ 74.00
Net proceeds from sale of stock	$ 452,300,000
Sale of stock, underwriters' discount	$ 15,800,000
Shares registered and available for issuance (in shares)			3,300
Restricted Stock/Unit Plan and Management Incentive Plan
Class of Stock [Line Items]
Common stock issued (in shares)			230
Dividend Reinvestment and Stock Purchase Plan
Class of Stock [Line Items]
Common stock issued (in shares)			142
Common stock issued, amount			$ 10,500,000
Term Loan Facility due December 30, 2022 \| Loans Payable
Class of Stock [Line Items]
Debt instrument, term		364 days
Equity Shelf Program
Class of Stock [Line Items]
Sale of stock, amount of common stock offered for sale (up to)				$ 500,000,000
Sale of stock, amount of common stock available for sale			$ 342,000,000

Acquisitions and Dispositions - Acquisitions - Narrative (Details) $ in Millions	12 Months Ended
	Dec. 31, 2022 USD ($)
MountainWest
Business Acquisition [Line Items]
Measurement period adjustments	$ 28.2

Commitments and Contingencies	12 Months Ended
Commitments and Contingencies	Dec. 31, 2022
Commitments and Contingencies Disclosure [Abstract]
Commitments and Contingencies	Note 10 - Commitments and Contingencies The Company and Southwest are defendants in miscellaneous legal proceedings. They are also parties to various regulatory proceedings. The ultimate dispositions of these proceedings are not presently determinable; however, it is the opinion of management that no litigation or regulatory proceeding to which the Company and Southwest are currently subject will have a material adverse impact on their financial position, results of operations, or cash flows. The Company maintains liability insurance that covers both Southwest and through the sale date, MountainWest, for various risks associated with the operation of the natural gas pipelines and facilities. In connection with these liability insurance policies, each entity is responsible for an initial deductible or self-insured retention amount per incident, after which the insurance carriers would be responsible for amounts up to the policy limits. For the policy year August 2022 to July 2023, these liability insurance policies require Southwest or MountainWest, as applicable, to be responsible for the first $1 million (self-insured retention) of each incident plus the first $4 million in aggregate claims above its self-insured retention in the policy year. When amounts are expected to be incurred above these amounts, subject to insurance carrier indemnity, a liability is recognized for the additional amount, in addition to a receivable from the insurance carrier amounts, without impact to earnings. Centuri maintains liability insurance for various risks associated with its operations. In connection with these liability insurance policies, Centuri is responsible for an initial deductible or self-insured retention amount per occurrence, after which the insurance carriers would be responsible for amounts up to the policy limits. For the policy year May 2022 to April 2023, Centuri is responsible for the first $750,000 (self-insured retention) per occurrence under these liability insurance policies. In August 2021, a natural gas pipe operated by Southwest was involved in an explosion that injured four individuals and damaged property. The explosion was caused by a leak in the pipe, and is under investigation. Individuals that were injured have each brought legal claims against Southwest and other parties. If Southwest is deemed fully or partially responsible, Southwest estimates its net exposure could be equal to the self-insured retention of $5 million (the maximum noted above). In 2021, pursuant to ASC 450 - Contingencies, Southwest recorded a $5 million liability related to this incident reflecting its best estimate of the probable loss at that time. Additional amounts, subject to insurance indemnity, have been recognized on the consolidated balance sheets, in accordance with the above-noted accounting for amounts above the self-insurance retention provisions, which were not material to our financial position. Any amounts above that which has already been recognized (to be covered by insurance) cannot be estimated as of the date these financial statements are issued. Other contingencies are also recognized where appropriate, if claims are brought, or expected to be brought, against the Company or Southwest, where management expects it may settle (or be required to settle) claims in cash, or in some cases, by means of insurance indemnification. The balance of such reserves was updated for additional accruals, including in regard to a contract dispute. For that item, $6.2 million was recorded during the second quarter of 2022, based on management’s estimate of Southwest’s exposure. The amount was paid in the fourth quarter of 2022 and the matter is closed. As described in Note 1 - Background, Organization, and Summary of Significant Accounting Policies, the November 2021 civil suit filed by the Icahn Group, against the Company and certain officers and directors, was subject to a stipulation of dismissal with prejudice in May 2022, pursuant to the terms of the Cooperation Agreement. On November 18, 2021, the City Pension Fund for Firefighters and Police Officers in the City of Miami Beach commenced a putative class action lawsuit in the Court of Chancery for the State of Delaware on behalf of a putative class of persons who purchased the Company’s stock. The action is captioned City Pension Fund for Firefighters and Police Officers in the City of Miami Beach v. Robert L. Boughner, et al., C.A. No. 2021-0990-KSJM (Del. Ch.). The complaint was later amended on November 30, 2021. The amended complaint named the Company and the individual members of the Board as defendants. The complaint sought to assert breach of fiduciary duty claims, alleging that the Board’s recommendation that stockholders reject Icahn’s offer to purchase shares of the Company’s common stock omitted material information about the Company’s financial analysis; and sought to have the Board approve Icahn’s slate of nominees as “continuing directors” under certain of the Company’s debt instruments. In March 2022, the City Pension Fund filed a motion for summary judgment on its claim; however, in April 2022, the City Pension Fund filed a notice of withdrawal of its motion for summary judgment. The Company believes that the claims lack merit and intends to vigorously defend against them. Through an assessment process of commitments and contingencies of any kind, the Company and Southwest may determine that certain costs are likely to be incurred in the future related to specific legal matters. In these circumstances and in accordance with accounting policies, the Company and Southwest will make an accrual, as necessary.

Background, Organization, and Summary of Significant Accounting Policies - Summary of Intangible Assets (Details) - Centuri - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	$ 471,035	$ 477,984
Accumulated Amortization	(75,787)	(51,479)
Net Carrying Amount	395,248	426,505
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	391,758	393,834
Accumulated Amortization	(63,509)	(42,886)
Net Carrying Amount	328,249	350,948
Trade names and trademarks
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount	79,277	79,650
Accumulated Amortization	(12,278)	(7,093)
Net Carrying Amount	$ 66,999	72,557
Customer contracts backlog
Finite-Lived Intangible Assets [Line Items]
Gross Carrying Amount		4,500
Accumulated Amortization		(1,500)
Net Carrying Amount		$ 3,000

Receivables and Related Allowances - Schedule of Allowance for Uncollectibles (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Accounts Receivable, Allowance for Credit Loss [Roll Forward]
Beginning Balance	$ 3,259	$ 4,334	$ 2,095
Additions charged to expense	12,707	5,415	4,693
Accounts written off, less recoveries	(11,136)	(6,490)	(2,454)
Ending Balance	$ 4,830	$ 3,259	$ 4,334

Receivables and Related Allowances (Tables)

12 Months Ended

Dec. 31, 2022

Receivables [Abstract]

Schedule of Accounts Receivable

The table below contains information about Southwest’s gas utility customer accounts receivable balance (net of allowance) at December 31, 2022 and 2021:


	December 31,
(Thousands of dollars)	2022		2021
Gas utility customer accounts receivable balance	$	225,317	$	169,114

Schedule of Percent of Customers by State

The following table represents the percentage of customers in each of Southwest’s three states at December 31, 2022, which was consistent with the prior year:


Percent of customers by state:
Arizona	54	%
Nevada	37	%
California	9	%

Schedule of Allowance for Uncollectibles

Southwest activity in the allowance account for uncollectibles is summarized as follows:


(Thousands of dollars)	Allowance for Uncollectibles
Balance, December 31, 2019	$	2,095
Additions charged to expense	4,693
Accounts written off, less recoveries	(2,454)
Balance, December 31, 2020	4,334
Additions charged to expense	5,415
Accounts written off, less recoveries	(6,490)
Balance, December 31, 2021	3,259
Additions charged to expense	12,707
Accounts written off, less recoveries	(11,136)
Balance, December 31, 2022	$	4,830

Acquisitions and Dispositions - Dispositions - Narrative (Details) - Disposal Group, Held-for-sale, Not Discontinued Operations - MountainWest - USD ($) $ in Thousands		1 Months Ended	12 Months Ended
	Sep. 22, 2022	Dec. 31, 2022	Dec. 31, 2022
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Ownership percentage disposed		100.00%	100.00%
Discontinued operation, consideration		$ 1,500,000	$ 1,500,000
Transition services agreement, period		6 months
Goodwill impairment loss			449,600
Disposal selling costs			5,819
Loss on disposal			$ (373,000)
Loss contingency, damages sought period	4 years
Loss contingency, damages sought value (up to)	$ 75,000

Debt (Tables)

12 Months Ended

Dec. 31, 2022

Debt Disclosure [Abstract]

Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt

Details surrounding the fair value and individual carrying values of instruments are provided in the table that follows.


	December 31,
	2022				2021
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
(Thousands of dollars)
Southwest Gas Corporation:
Debentures:
Notes, 6.1%, due 2041	$	125,000	$	113,184	$	125,000	$	166,380
Notes, 4.05%, due 2032	600,000		527,052		—		—
Notes, 3.875%, due 2022	—		—		250,000		250,603
Notes, 4.875%, due 2043	250,000		195,703		250,000		307,538
Notes, 3.8%, due 2046	300,000		209,169		300,000		329,055
Notes, 3.7%, due 2028	300,000		275,043		300,000		325,191
Notes, 4.15%, due 2049	300,000		218,712		300,000		342,030
Notes, 2.2%, due 2030	450,000		353,763		450,000		440,838
Notes, 3.18%, due 2051	300,000		185,523		300,000		292,116
Notes, 5.8%, due 2027	300,000		305,913		—		—
8% Series, due 2026	75,000		80,027		75,000		92,623
Medium-term notes, 7.78% series, due 2022	—		—		25,000		25,122
Medium-term notes, 7.92% series, due 2027	25,000		26,840		25,000		31,555
Medium-term notes, 6.76% series, due 2027	7,500		7,662		7,500		8,949
Unamortized discount and debt issuance costs	(29,471)				(19,959)
	3,003,029				2,387,541
Revolving credit facility and commercial paper	50,000		50,000		130,000		130,000
Industrial development revenue bonds:
Tax-exempt Series A, due 2028	50,000		50,000		50,000		50,000
2003 Series A, due 2038	50,000		50,000		50,000		50,000
2008 Series A, due 2038	50,000		50,000		50,000		50,000
2009 Series A, due 2039	50,000		50,000		50,000		50,000
Unamortized discount and debt issuance costs	(1,733)				(1,938)
	198,267				198,062
Less: current maturities	—				(275,000)
Southwest Gas Corporation total long-term debt, less current maturities	$	3,251,296			$	2,440,603


Southwest Gas Holdings, Inc.:
Centuri secured term loan facility	$	1,008,550	$	995,852	$	1,117,138	$	1,117,841
Centuri secured revolving credit facility	81,955		82,315		103,329		103,749
MountainWest unsecured senior notes, 3.53%, due in 2028*	—		—		102,078		102,078
MountainWest unsecured senior notes, 4.875%, due in 2041*	—		—		199,926		199,926
MountainWest unsecured senior notes, 3.91%, due in 2038*	—		—		147,735		147,735
Other debt obligations	126,844		118,314		51,665		50,003
Unamortized discount and debt issuance costs	(20,789)				(24,466)
Less: current maturities	(44,557)				(22,324)
Southwest Gas Holdings, Inc. total long-term debt, less current maturities	$	4,403,299			$	4,115,684

Summary of Effective Interest Rates on Variable-Rate IDRBs

The effective interest rates on Southwest’s variable-rate IDRBs are included in the table below:


	December 31,
	2022		2021
2003 Series A	4.68	%	0.91	%
2008 Series A	4.84	%	0.90	%
2009 Series A	4.67	%	0.88	%
Tax-exempt Series A	4.30	%	0.92	%

Estimated Maturities of Long-Term Debt

Estimated maturities of long-term debt for the next five years are:


(Thousands of dollars)	2023		2024		2025		2026		2027		Total
Southwest Gas Corporation:
Debentures	$	—	$	—	$	—	$	75,000	$	332,500	$	407,500
Revolving credit facility and commercial paper	—		—		50,000		—		—		50,000
Total	—		—		50,000		75,000		332,500		457,500
Southwest Gas Holdings, Inc.:
Centuri secured term loan facility	14,313		11,450		11,450		11,450		11,450		60,113
Centuri secured revolving credit facility	—		—		—		81,955		—		81,955
Other debt obligations	30,245		31,102		29,554		28,651		7,292		126,844
Total	$	44,558	$	42,552	$	91,004	$	197,056	$	351,242	$	726,412

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 3
-Subparagraph (SX 210.12-04(a))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e24072-122690

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28541-108399

Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21506-112644

Reference 5: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
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-Paragraph 69B
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612

Reference 6: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
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-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399

Reference 7: http://www.xbrl.org/2003/role/exampleRef
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-Name Accounting Standards Codification
-Topic 470
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-Paragraph 69E
-URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495743-112612

Reference 8: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 9: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21538-112644

Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI https://asc.fasb.org/extlink&oid=123599511&loc=d3e64711-112823

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
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-Section 55
-Paragraph 8
-URI https://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
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-URI https://asc.fasb.org/extlink&oid=126973232&loc=d3e21475-112644

+ Details

Pension and Other Postretirement Benefits - Narrative (Details)	12 Months Ended
	Dec. 31, 2022 USD ($) plan	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation plan, payment term, option one	10 years
Deferred compensation plan, payment term, option two	15 years
Deferred compensation plan, payment term, option three	20 years
Future estimated funding amount	$ 59,000,000
Multiemployer plan, contributions by employer	3,800,000	$ 0	$ 0
Multiemployer plan, special surcharges	$ 0
Multiemployer pension plans, number of critical plans \| plan	8
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Asset return assumption	6.50%	6.50%	6.75%
Future estimated funding amount	$ 56,000,000
PBOP
Defined Benefit Plan Disclosure [Line Items]
Asset return assumption	6.50%	6.50%	6.75%
PBOP \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Per capita cost of covered health care benefits medical rate trend assumption	6.00%
PBOP \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Per capita cost of covered health care benefits medical rate trend assumption	4.50%
Southwest Gas Corporation
Defined Benefit Plan Disclosure [Line Items]
EIP, percent of compensation deferred with match	50.00%
EIP, employer matching contribution, percent of match	3.50%
Employee investment plan cost	$ 6,900,000	$ 6,100,000	$ 5,900,000
Deferred compensation plan, maximum percentage of salary deferral	100.00%
Deferred compensation plan, matching percentage	3.50%
Deferred Compensation Plan, percent of amount deferred with match	50.00%
Period of additional option to receive payment	5 years
Deferred compensation, percentage of multiple interest rate	150.00%
Increments of change to the discount rate	0.25%
Increase of discount rate	2.25%
Increase of asset return assumption	0.25%
Asset return assumption	6.75%	6.50%
Centuri
Defined Benefit Plan Disclosure [Line Items]
Deferred compensation plan, maximum percentage of salary deferral	80.00%
Deferred compensation plan, matching percentage	5.00%
Defined contribution plans, employer contribution amount	$ 13,000,000	$ 9,000,000	9,000,000
Deferred compensation plan, percentage of contributions with matching	100.00%
Deferred compensation plan, vesting percentage of deferral	100.00%
Multiemployer plan, contributions by employer	$ 71,000,000	$ 57,400,000	$ 44,300,000

Acquisitions and Dispositions - Business Acquisition, Pro Forma Information (Details) - Riggs Distler and MountainWest acquisitions - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Business Acquisition [Line Items]
Business acquisition, pro forma adjustment, transaction costs		$ 48,700
Business acquisition, pro forma adjustment, transaction costs, incremental interest expense	$ 48,400	52,100
Total operating revenues	4,236,000	3,980,000
Net income attributable to Southwest Gas Holdings, Inc.	$ 278,000	$ 276,000
Basic earnings per share (in USD per Share)	$ 4.70	$ 4.93
Diluted earnings per share (in USD per Share)	$ 4.69	$ 4.93

Pension and Other Postretirement Benefits (Tables)

12 Months Ended

Dec. 31, 2022

Retirement Benefits [Abstract]

Schedule of Assumptions Used

The rates are presented in the table below:


	December 31,
	2022		2021
Discount rate	5.25	%	3.00	%
Weighted-average rate of compensation increase	3.25	%	3.25	%
Asset return assumption	6.75	%	6.50	%

Schedule of Defined Benefit Plans Disclosures

The following table sets forth the retirement plan, SERP, and PBOP funded statuses and amounts recognized on the Consolidated Balance Sheets and Consolidated Statements of Income.


	Year Ended December 31,
	2022									2021
(Thousands of dollars)	Qualified Retirement Plan			SERP			PBOP			Qualified Retirement Plan			SERP			PBOP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$	1,531,197		$	49,530		$	84,226		$	1,499,239		$	53,631		$	82,205
Service cost	44,110			424			1,941			41,159			526			1,691
Interest cost	45,006			1,441			2,452			40,432			1,431			2,193

Actuarial loss (gain)	(399,066)			(6,134)			(18,260)			8,908			(3,244)			3,438
Benefits paid	(61,796)			(3,164)			(4,922)			(58,541)			(2,814)			(5,301)
Benefit obligation at end of year (PBO/PBO/APBO)	1,159,451			42,097			65,437			1,531,197			49,530			84,226
Change in plan assets:
Market value of plan assets at beginning of year	1,366,043			—			52,168			1,186,433			—			52,286
Actual return on plan assets	(330,203)			—			(6,036)			136,151			—			7,717
Employer contributions	56,000			3,164			—			102,000			2,814			—
Benefits paid	(61,796)			(3,164)			(7,673)			(58,541)			(2,814)			(7,835)
Market value of plan assets at end of year	1,030,044			—			38,459			1,366,043			—			52,168
Funded status at year end	$	(129,407)		$	(42,097)		$	(26,978)		$	(165,154)		$	(49,530)		$	(32,058)
Weighted-average assumptions (benefit obligation):
Discount rate	5.25		%	5.25		%	5.25		%	3.00		%	3.00		%	3.00		%
Weighted-average rate of compensation increase	3.25		%	3.25		%	N/A			3.25		%	3.25		%	N/A

Schedule of Accumulated Benefit Obligation

The accumulated benefit obligation for the retirement plan and the SERP is presented below:


	December 31,
(Thousands of dollars)	2022		2021
Retirement plan	$	1,074,493	$	1,395,773
SERP	39,263		46,885

Schedule of Expected Benefit Payments

Benefits expected to be paid for pension, SERP, and PBOP over the next 10 years are as follows:


(Millions of dollars)	2023		2024		2025		2026		2027		2028-2032
Pension	$	65.0	$	67.0	$	68.0	$	69.0	$	71.0	$	377.0
SERP	3.3		3.3		3.2		3.1		3.1		14.6
PBOP	5.1		5.2		5.2		5.1		5.2		25.6

Schedule of Net Benefit Cost

Components of net periodic benefit cost:


	Qualified Retirement Plan						SERP						PBOP
(Thousands of dollars)	2022		2021		2020		2022		2021		2020		2022		2021		2020
Service cost	$44,110		$41,159		$34,299		$424		$526		$389		$1,941		$1,691		$1,581
Interest cost	45,006		40,432		45,555		1,441		1,431		1,604		2,452		2,193		2,582
Expected return on plan assets	(79,913)		(72,352)		(65,296)		—		—		—		(3,228)		(3,239)		(3,408)
Amortization of prior service cost	—		—		—		—		—		—		175		959		1,155
Amortization of net actuarial loss	32,468		41,955		36,025		2,350		2,642		1,805		—		—		—
Net periodic benefit cost	$41,671		$51,194		$50,583		$4,215		$4,599		$3,798		$1,340		$1,604		$1,910
Weighted-average assumptions (net benefit cost)
Discount rate	3.00	%	2.75	%	3.50	%	3.00	%	2.75	%	3.50	%	3.00	%	2.75	%	3.50	%
Expected return on plan assets	6.50	%	6.50	%	6.75	%	N/A		N/A		N/A		6.50	%	6.50	%	6.75	%
Weighted-average rate of compensation increase	3.25	%	3.00	%	3.25	%	3.25	%	3.00	%	3.25	%	N/A		N/A		N/A

Schedule of Amounts Recognized in Other Comprehensive Income

The following table represents amounts (before income tax impacts) included in AOCI (in the tables above), that have not yet been recognized in net periodic benefit cost:


	Year Ended December 31,
(Thousands of dollars)	2022		2021
Net actuarial loss	$	(360,113)	$	(399,010)
Prior service cost	(1,353)		(1,528)
Less: amount recognized in regulatory assets	311,124		339,356
Recognized in AOCI	$	(50,342)	$	(61,182)

Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income


	Year Ended December 31,
	2022								2021								2020
(Thousands of dollars)	Total		Qualified Retirement Plan		SERP		PBOP		Total		Qualified Retirement Plan		SERP		PBOP		Total		Qualified Retirement Plan		SERP		PBOP
Net actuarial loss (gain) (a)	$	(4,079)	$	11,049	$	(6,133)	$	(8,995)	$	(59,176)	$	(54,892)	$	(3,245)	$	(1,039)	$	57,539	$	45,665	$	7,240	$	4,634
Amortization of prior service cost (b)	(175)		—		—		(175)		(959)		—		—		(959)		(1,155)		—		—		(1,155)
Amortization of net actuarial loss (b)	(34,818)		(32,468)		(2,350)		—		(44,597)		(41,955)		(2,642)		—		(37,830)		(36,025)		(1,805)		—
Prior service cost	—		—		—		—		—		—		—		—		—		—		—		—
Regulatory adjustment	28,232		19,062		—		9,170		88,194		86,196		—		1,998		(7,435)		(3,956)		—		(3,479)
Recognized in other comprehensive (income) loss	(10,840)		(2,357)		(8,483)		—		(16,538)		(10,651)		(5,887)		—		11,119		5,684		5,435		—
Net periodic benefit costs recognized in net income	47,226		41,671		4,215		1,340		57,397		51,194		4,599		1,604		56,291		50,583		3,798		1,910
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	$	36,386	$	39,314	$	(4,268)	$	1,340	$	40,859	$	40,543	$	(1,288)	$	1,604	$	67,410	$	56,267	$	9,233	$	1,910

Schedule of Fair Value of Plan Assets

The following table sets forth, by level within the three-level fair value hierarchy, the fair values of the assets of the qualified pension plan and the PBOP as of December 31, 2022 and 2021. The SERP has no assets.


	December 31,
	2022						2021
(Thousands of dollars)	Qualified Retirement Plan		PBOP		Total		Qualified Retirement Plan		PBOP		Total
Assets at fair value:
Level 1 – Quoted prices in active markets for identical financial assets
Mutual funds	$	—	$	31,631	$	31,631	$	—	$	35,194	$	35,194
Total Level 1 Assets (1)	—		31,631		31,631		—		35,194		35,194
Level 2 – Significant other observable inputs
Commingled trust equity funds (2)
Global	266,368		1,673		268,041		373,936		4,538		378,474
International	117,976		741		118,717		158,461		1,923		160,384
U.S. equity securities	184,300		1,159		185,459		279,062		3,386		282,448
Emerging markets	62,436		392		62,828		82,004		995		82,999
Commingled trust fixed income funds (3)	390,070		2,450		392,520		463,942		5,630		469,572
Pooled funds and mutual funds	6,359		412		6,771		5,979		500		6,479
Government fixed income and mortgage backed securities	159		1		160		196		2		198
Total Level 2 assets (4)	1,027,668		6,828		1,034,496		1,363,580		16,974		1,380,554
Total Plan assets at fair value	1,027,668		38,459		1,066,127		1,363,580		52,168		1,415,748
Insurance company general account contracts (5)	2,376		—		2,376		2,463		—		2,463
Total Plan assets	$	1,030,044	$	38,459	$	1,068,503	$	1,366,043	$	52,168	$	1,418,211

(1)The Mutual funds category above is a balanced fund that invests in a diversified portfolio of common stocks, preferred stocks, and fixed-income securities. Under normal circumstances the balanced fund will hold no more than 75%, and no less than 25%, of its total assets in equity securities. The fund seeks regular income, conservation of principal, and an opportunity for long-term growth of principal and income.

(2)The commingled trust equity funds include common collective trusts that invest in a diversified portfolio of securities regularly traded on securities exchanges. These funds are shown in the above table at net asset value (“NAV”), which is the value of securities in the fund less the amount of any liabilities outstanding. Strategies employed by the funds include investment in:

▪Global equities, including domestic equities

▪International developed countries equities

▪Domestic equities

▪Emerging markets equities

Shares in the commingled trust equity funds may be redeemed given one business day notice. While they are trust equity funds and reported at NAV, due to the short redemption notice period, the lack of redemption fees, the fact that the underlying investments are exchange-traded, and that substantial liabilities do not exist subject to the NAV calculation, these investments are viewed as indirectly observable (Level 2) in the fair value hierarchy and are therefore not excluded from the body of the fair value table as a reconciling item.

The global fund provides diversified exposure to global equity markets. The fund seeks to provide long-term capital growth by investing primarily in securities listed on the major developed equity markets of the U.S., Europe, and Asia, as well as within those listed on emerging country equity markets on a tactical basis.

The international fund invests in international financial markets, primarily those of developed economies in Europe and the Pacific Basin. The fund invests primarily in equity securities issued by foreign corporations, but may invest in other securities perceived as offering attractive investment return opportunities.

The domestic equities securities funds include a large and medium capitalization fund and a small capitalization fund. The large and medium capitalization fund is designed to track the performance of the large and medium capitalization companies contained in the index, which represents approximately 90% of the market capitalization of the U.S. stock market. The small capitalization fund is designed to provide maximum long-term appreciation through investments that are well diversified by industry.

The emerging markets fund invests in countries defined as an emerging market country. Fund investments are made directly in each country or, where direct investment is inefficient or prohibited, through appropriate financial instruments or participation in commingled funds. Major emerging markets include Brazil, India, China, and other developing countries around the world.

(3)The commingled trust fixed income funds consist primarily of fixed income debt securities issued by the U.S. Treasury, government agencies, and fixed income debt securities issued by corporations. The fixed income fund investments may include the use of high yield, international fixed income securities and other instruments, including derivatives, to ensure prudent diversification over a broad spectrum

of investments. The changes in the value of the fixed income funds are intended to offset the changes in the pension plan liabilities due to changes in the discount rate.

These funds are shown in the above table at NAV. Investments in the commingled trust fixed equity funds may be redeemed given one business day notice. While they are fixed income funds and reported at NAV, due to the short redemption notice period, the lack of redemption fees, the fact that the underlying investments are exchange-traded, and that substantial liabilities do not exist subject to the NAV calculation, these investments are viewed as indirectly observable (Level 2), and are also not excluded from the body of the fair value table as a reconciling item.

(4)With the exception of items (2) and (3), which are discussed above, the Level 2 assets consist mainly of pooled funds and mutual funds. These funds are collective short-term funds that invest in Treasury bills and money market funds and are used as a temporary cash repository.

(5)The insurance company general account contracts are annuity insurance contracts used to pay the pensions of employees who retired prior to 1989. The balance of the account disclosed in the above table is the contract value, which is the result of deposits, withdrawals, and interest credits.

Regulatory Assets and Liabilities

12 Months Ended

Dec. 31, 2022

Regulated Operations [Abstract]

Regulatory Assets and Liabilities

Note 5 - Regulatory Assets and Liabilities

Southwest is subject to the regulation of the Arizona Corporation Commission (“ACC”), the Public Utilities Commission of Nevada (“PUCN”), the California Public Utilities Commission (“CPUC”), and the FERC. Accounting policies for Southwest conform to U.S. GAAP applicable to rate-regulated entities and reflect the effects of the ratemaking process. Accounting treatment for rate-regulated entities allows for deferral as regulatory assets, costs that otherwise would be expensed, if it is probable that future recovery from customers will occur. If rate recovery is no longer probable, due to competition or the actions of regulators, the related regulatory asset is required to be written off. Regulatory liabilities are recorded if it is probable that revenues will be reduced for amounts that will be refunded to customers through the ratemaking process. Management records regulatory assets and liabilities based on decisions of the commissions noted above, including the issuance of regulatory orders and precedents established by these commissions. The regulated operations have generally been successful in seeking recovery of regulatory assets, and regularly file rate cases or other administrative filings in the various jurisdictions, in some cases, to establish the basis for recovering regulatory assets reflected in accounting records.

The following table represents existing regulatory assets and liabilities:


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.*				Southwest Gas Corporation
Regulatory assets:
Accrued pension and other postretirement benefit costs (1)	$	311,124	$	339,356	$	339,356
Deferred purchased gas costs (2)	450,120		291,145		291,145
Settled interest rate hedges (3)	—		31,278		—
Accrued purchased gas costs (4)	207,368		51,631		51,631
Unamortized premium on reacquired debt (5)	14,707		16,283		16,283
Accrued absence time (9)	17,854		16,975		16,975
Margin, interest- and tax-tracking (10)	21,024		22,709		22,709
Other (12)	65,981		62,233		60,798
	$	1,088,178	$	831,610	798,897
Regulatory liabilities:
Deferred purchased gas costs (2)	—		(5,736)		—
Accumulated removal costs (6)	(445,000)		(482,558)		(424,000)
Unamortized gain on reacquired debt (7)	(6,572)		(7,108)		(7,108)
Regulatory excess deferred/other taxes and gross-up (8)	(424,921)		(511,567)		(446,333)
Margin, interest- and property tax-tracking (10)	(10,920)		(8,523)		(8,523)
Unrecognized other postretirement benefit costs (11)	—		(17,815)		—
Other (12)	(5,393)		(10,321)		(8,573)
Net regulatory assets (liabilities)	$	195,372	$	(212,018)	$	(95,640)

*Southwest Gas Holdings, Inc. includes the regulatory assets and liabilities associated with MountainWest only as of December 31, 2021, due to the held-for-sale classification of the disposal group as of December 31, 2022. As of that date, the regulatory assets and liabilities for Southwest Gas Corporation are the same, including in amount, as those reflected for the Company.

(1)Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 11 - Pension and Other Postretirement Benefits).

(2)Balance recovered or refunded on an ongoing basis with interest.

(3)Reflects MountainWest interest rate cash flow hedges entered into in association with the issuance of $180 million principal balance 4.875% unsecured senior notes due in 2041 that are amortized to interest expense over the life of the debt instrument. The current portion at December 31, 2021 was included in Prepaid and other current assets and the long-term portion was included in Deferred charges and other assets on the Company’s 2021 Consolidated Balance Sheet.

(4)Included in Prepaid and other current assets on the Consolidated Balance Sheets. Balance recovered or refunded on an ongoing basis.

(5)Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments.

(6)Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets. In 2021, substantially all amounts related to MountainWest were also included in Other deferred credits and other long-term liabilities, except $2 million which was included in Other current liabilities on the Company’s Consolidated Balance Sheet.

(7)Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets. Amortized over life of debt instruments.

(8)Includes remeasurement/reduction of the net accumulated deferred income tax liability from U.S. tax reform. The reduction (excess accumulated deferred taxes, or “EADIT”) became a regulatory liability with tax gross-up. EADIT reduces rate base, and is expected to be returned to utility customers in accordance with IRS and regulatory requirements. Included generally in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets, except for $30.3 million in 2022 which is in Other current liabilities. Amount also includes difference in current taxes required to be returned to customers and a separate $2.7 million gross-up related to contributions in aid of construction.

(9)Regulatory recovery occurs on a one-year lag basis through the labor loading process. Included in Prepaid and other current assets on the Consolidated Balance Sheets.

(10)Margin tracking/decoupling mechanisms are alternative revenue programs; revenue associated with under-collections (for the difference between authorized margin levels and amounts billed to customers through rates currently) is recognized as revenue so long as recovery is expected to take place within 24 months. Total category asset balances are included in Prepaid and other current assets on the Consolidated Balance Sheets. Total category liability balances are included in Other current liabilities and Other deferred credits and other long-term liabilities.

(11)Reflected a regulatory liability at MountainWest for the collection of postretirement benefit costs allowed in rates in excess of expenses incurred, included in Other deferred credits and other long-term liabilities on the Company’s Consolidated Balance Sheet as of December 31, 2021, before MountainWest balances were included as Current liabilities held for sale.

(12)The following tables detail the components of Other regulatory assets and liabilities. Other regulatory assets are included in either Prepaid and other current assets or Deferred charges and other assets on the Consolidated Balance Sheets (as indicated). Recovery periods vary. Other regulatory liabilities are included in either Other current liabilities or Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets (as indicated).


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.				Southwest Gas Corporation
Other Regulatory Assets:
State mandated public purpose programs (including low income and conservation programs) (a) (e)	$	18,693	$	15,239	$	15,239
Infrastructure replacement programs and similar (b) (e)	8,533		6,545		6,545
Environmental compliance programs (c) (e)	5,803		6,807		6,807
Pension tracking mechanism (b)	13,098		10,281		10,281
Other (d)	19,854		23,361		21,926
	$	65,981	$	62,233	$	60,798

a)Included in Prepaid and other current assets on the Consolidated Balance Sheets.

b)Included in Deferred charges and other assets on the Consolidated Balance Sheets, except $930,000 which is included in Prepaid and other current assets in 2022.

c)In 2022, approximately $5 million of these balances included in Prepaid and other current assets and $825,000 in Deferred charges and other assets on the Consolidated Balance Sheets. In 2021, approximately $5.8 million included in Prepaid and other current assets and $1 million included in Deferred charges and other assets on the Consolidated Balance Sheets.

d)In 2022, approximately $6.4 million included in Prepaid and other current assets and $13.4 million included in Deferred charges and other assets on the Consolidated Balance Sheets. In 2021, for Southwest Gas Corporation, $6.7 million included in Prepaid and other current assets and $15.2 million included in Deferred charges and other assets on the Consolidated Balance Sheets. For the Company in 2021, $7.7 million included in Prepaid and other current assets and $15.6 million included in Deferred charges and other assets on the Consolidated Balance Sheets.

e)Balance recovered or refunded on an ongoing basis, generally with interest.


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.				Southwest Gas Corporation
Other Regulatory Liabilities:
State mandated public purpose programs (including low income and conservation programs) (a) (c)	$	(1,567)	$	(1,886)	$	(1,886)
Environmental compliance programs (c) (d)	—		(4,182)		(4,182)

Other (b) (c)	(3,826)		(4,253)		(2,505)
	$	(5,393)	$	(10,321)	$	(8,573)

a)Included in Other current liabilities on the Consolidated Balance Sheets.

b)Included in Other current liabilities, except $823,000, in 2022, which is included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets.

c)Balance typically recovered or refunded on an ongoing basis, generally with interest.

d)In 2021, included in Other current liabilities on the Consolidated Balance Sheets.

CONSOLIDATED STATEMENTS OF INCOME - Southwest - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Regulated operations revenues	$ 2,199,682	$ 1,521,790	$ 1,350,585
Operating expenses:
Net cost of gas sold	799,060	430,907	342,837
Operations and maintenance	636,766	473,146	408,116
Depreciation and amortization	470,455	371,041	332,027
Taxes other than income taxes	93,383	80,343	63,460
Total operating expenses	4,984,407	3,310,904	2,875,869
Operating income (loss)	(24,398)	369,547	423,004
Other income and (expenses):
Net interest deductions	(242,750)	(119,198)	(111,477)
Other income (deductions)	(6,189)	(3,499)	(6,789)
Total other income and (expenses)	(248,939)	(122,697)	(118,266)
Income (loss) before income taxes	(273,337)	246,850	304,738
Income tax expense (benefit)	(75,653)	39,648	65,753
Net income (loss) attributable to Southwest Gas Holdings, Inc.	(203,290)	200,779	232,324
Southwest Gas Corporation
Regulated operations revenues	1,935,069	1,521,790	1,350,585
Operating expenses:
Net cost of gas sold	789,216	430,907	342,837
Operations and maintenance	491,928	438,550	406,382
Depreciation and amortization	263,043	253,398	235,295
Taxes other than income taxes	83,197	80,343	63,460
Total operating expenses	1,627,384	1,203,198	1,047,974
Operating income (loss)	307,685	318,592	302,611
Other income and (expenses):
Net interest deductions	(115,880)	(97,560)	(101,148)
Other income (deductions)	(6,884)	(4,559)	(6,590)
Total other income and (expenses)	(122,764)	(102,119)	(107,738)
Income (loss) before income taxes	184,921	216,473	194,873
Income tax expense (benefit)	30,541	29,338	35,755
Net income (loss) attributable to Southwest Gas Holdings, Inc.	$ 154,380	$ 187,135	$ 159,118

Income Taxes - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$ 109,093	$ 116,496
Employee benefits	29,307	39,181
Net operating losses	223,557	102,853
Deferred payroll taxes	0	6,344
Lease-related item	19,745	18,462
Goodwill impairment	105,507	0
Other	13,197	12,149
Valuation allowance	(2,197)	(4,902)
Deferred tax assets, total	498,209	290,583
Deferred tax liabilities:
Property-related items, including accelerated depreciation	873,328	843,559
Regulatory balancing accounts	154,124	77,818
Debt-related costs	(2,365)	2,277
Intangibles	105,668	97,860
Lease-related item	21,164	17,254
Other	28,275	20,562
Deferred tax liabilities, gross	1,180,194	1,059,330
Net deferred tax liabilities	681,985	768,747
Southwest Gas Corporation
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	94,273	101,133
Employee benefits	(12,604)	(4,671)
Net operating losses	135,200	59,119
Deferred payroll taxes	0	892
Other	2,512	6,777
Valuation allowance	0	(22)
Deferred tax assets, total	219,381	163,228
Deferred tax liabilities:
Property-related items, including accelerated depreciation	733,011	703,374
Regulatory balancing accounts	154,124	77,818
Debt-related costs	2,062	2,277
Other	14,132	18,587
Deferred tax liabilities, gross	903,329	802,056
Net deferred tax liabilities	$ 683,948	$ 638,828

Receivables and Related Allowances

12 Months Ended

Dec. 31, 2022

Receivables [Abstract]

Receivables and Related Allowances

Note 4 - Receivables and Related Allowances

Business activity with respect to natural gas utility operations is conducted with customers located within the three-state region of Arizona, Nevada, and California. Southwest’s accounts receivable are short-term in nature, with billing due dates customarily not extending beyond one month, with customers’ credit worthiness assessed upon account creation by evaluation of other utility service or their credit file, and related payment history. Although Southwest seeks generally to minimize its credit risk related to utility operations by requiring security deposits from new customers, imposing late fees, and actively pursuing collection on overdue accounts, some accounts are ultimately not collected. Customer accounts are subject to collection procedures that vary by jurisdiction (late fee assessment, notice requirements for disconnection of service, and procedures for actual disconnection and/or reestablishment of service). After disconnection of service, accounts are customarily written off approximately two months after disconnection if the account remains inactive. Dependent upon the jurisdiction, reestablishment of service requires both payment of previously unpaid balances and additional deposit requirements. Provisions for uncollectible accounts are recorded monthly based on experience, consideration of current and expected future conditions, customer and rate composition, and write-off processes. They are included in the ratemaking process as a cost of service. The Nevada jurisdictions have a regulatory mechanism associated with the gas-cost-related portion of uncollectible accounts. Such amounts are deferred and collected through a surcharge in the ratemaking process. Southwest lifted the moratorium on disconnection of natural gas service for non-payment in Arizona and Nevada in September 2021, which was initiated (at the same time as a moratorium on late fees) in March 2020 in response to the COVID-19 pandemic. The moratorium on disconnection in California ended in November 2021. Southwest recommenced assessing late fees on past-due balances in Arizona and Nevada in April 2021, and in California in August 2021. After these moratoriums were lifted, Southwest resumed collection efforts. These moratoriums have influenced our bad debt expense and write-offs through 2022. Southwest continues to actively work with customers experiencing financial hardship by means of flexible payment options and partnering with assistance agencies. Management continues to monitor expected credit losses in light of the impacts of events/conditions such as COVID-19, local/regional inflation, and others. In addition, management is monitoring the impact of certain residential disconnection protections recently established in Southwest’s California jurisdictions, such as prohibiting credit deposits and fees for reconnection, among other things. While a two-way balancing account was permitted to track residential uncollectible accounts for future recovery, the mechanism is subject to a cap, above which uncollectible expense would nonetheless be incurred and recognized. The allowance as of December 31, 2022 reflects the expected impact from the pandemic on balances as of that date, including consideration of customers’ current and future ability to pay those amounts that are due.

Utility infrastructure services accounts receivable are recorded at face amounts less an allowance for doubtful accounts. Centuri’s customers are generally investment-grade gas and electric utility companies for which Centuri has historically recognized an insignificant amount of write-offs. Centuri’s accounts receivable balances carry standard payment terms of up to 60 days. Centuri maintains an allowance that is estimated based on historical collection experience, current and estimated future economic and market conditions, and a review of the current status of each customer's accounts receivable balance. Account balances are monitored at least monthly, and are charged off against the allowance when management determines it is probable the balance will not be recovered. Centuri has not been significantly impacted, nor does it anticipate it will experience significant difficulty in collecting amounts due, given the nature of its customers, as a result of the COVID-19 environment, historically high inflation, or other conditions.

The table below contains information about Southwest’s gas utility customer accounts receivable balance (net of allowance) at December 31, 2022 and 2021:


	December 31,
(Thousands of dollars)	2022		2021
Gas utility customer accounts receivable balance	$	225,317	$	169,114

The following table represents the percentage of customers in each of Southwest’s three states at December 31, 2022, which was consistent with the prior year:


Percent of customers by state:
Arizona	54	%
Nevada	37	%
California	9	%

Southwest activity in the allowance account for uncollectibles is summarized as follows:


(Thousands of dollars)	Allowance for Uncollectibles
Balance, December 31, 2019	$	2,095
Additions charged to expense	4,693
Accounts written off, less recoveries	(2,454)
Balance, December 31, 2020	4,334
Additions charged to expense	5,415
Accounts written off, less recoveries	(6,490)
Balance, December 31, 2021	3,259
Additions charged to expense	12,707
Accounts written off, less recoveries	(11,136)
Balance, December 31, 2022	$	4,830

At December 31, 2022, the utility infrastructure services segment (Centuri) had $632.1 million in combined customer accounts and contracts receivable. The allowance for doubtful accounts at Centuri as of December 31, 2022 was $4.3 million. The allowance for uncollectibles and write-offs related to Centuri customers were insignificant for all periods prior to December 31, 2022 and not reflected in the table above.

Pension and Other Postretirement Benefits - Schedule of Fair Value of Plan Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 1,068,503	$ 1,418,211
Equity Securities \| Maximum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	75.00%
Equity Securities \| Minimum
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, target allocation, percentage	25.00%
Fair Value, Inputs, Level 1 and 2
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 1,066,127	1,415,748
Level 1 – Quoted prices in active markets for identical financial assets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	31,631	35,194
Level 1 – Quoted prices in active markets for identical financial assets \| Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	31,631	35,194
Level 2 – Significant other observable inputs
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,034,496	1,380,554
Level 2 – Significant other observable inputs \| Global
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	268,041	378,474
Level 2 – Significant other observable inputs \| International
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	118,717	160,384
Level 2 – Significant other observable inputs \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	185,459	282,448
Level 2 – Significant other observable inputs \| Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	62,828	82,999
Level 2 – Significant other observable inputs \| Commingled trust fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	392,520	469,572
Level 2 – Significant other observable inputs \| Pooled funds and mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6,771	6,479
Level 2 – Significant other observable inputs \| Government fixed income and mortgage backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	160	198
Insurance company general account contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	2,376	2,463
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,030,044	1,366,043	$ 1,186,433
Qualified Retirement Plan \| Fair Value, Inputs, Level 1 and 2
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,027,668	1,363,580
Qualified Retirement Plan \| Level 1 – Quoted prices in active markets for identical financial assets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Qualified Retirement Plan \| Level 1 – Quoted prices in active markets for identical financial assets \| Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	0	0
Qualified Retirement Plan \| Level 2 – Significant other observable inputs
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,027,668	1,363,580
Qualified Retirement Plan \| Level 2 – Significant other observable inputs \| Global
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	266,368	373,936
Qualified Retirement Plan \| Level 2 – Significant other observable inputs \| International
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	117,976	158,461
Qualified Retirement Plan \| Level 2 – Significant other observable inputs \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	184,300	279,062
Qualified Retirement Plan \| Level 2 – Significant other observable inputs \| Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	62,436	82,004
Qualified Retirement Plan \| Level 2 – Significant other observable inputs \| Commingled trust fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	390,070	463,942
Qualified Retirement Plan \| Level 2 – Significant other observable inputs \| Pooled funds and mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6,359	5,979
Qualified Retirement Plan \| Level 2 – Significant other observable inputs \| Government fixed income and mortgage backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	159	196
Qualified Retirement Plan \| Insurance company general account contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	2,376	2,463
PBOP
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	38,459	52,168	$ 52,286
PBOP \| Fair Value, Inputs, Level 1 and 2
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	38,459	52,168
PBOP \| Level 1 – Quoted prices in active markets for identical financial assets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	31,631	35,194
PBOP \| Level 1 – Quoted prices in active markets for identical financial assets \| Mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	31,631	35,194
PBOP \| Level 2 – Significant other observable inputs
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	6,828	16,974
PBOP \| Level 2 – Significant other observable inputs \| Global
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,673	4,538
PBOP \| Level 2 – Significant other observable inputs \| International
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	741	1,923
PBOP \| Level 2 – Significant other observable inputs \| U.S. equity securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1,159	3,386
PBOP \| Level 2 – Significant other observable inputs \| Emerging markets
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	392	995
PBOP \| Level 2 – Significant other observable inputs \| Commingled trust fixed income funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	2,450	5,630
PBOP \| Level 2 – Significant other observable inputs \| Pooled funds and mutual funds
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	412	500
PBOP \| Level 2 – Significant other observable inputs \| Government fixed income and mortgage backed securities
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	1	2
PBOP \| Insurance company general account contracts
Defined Benefit Plan Disclosure [Line Items]
Defined benefit plan, plan assets, amount	$ 0	$ 0

Segment Information - Narrative (Details)	12 Months Ended
Segment Information - Narrative (Details)	Dec. 31, 2022 segment
Segment Reporting Information [Line Items]
Number of reportable segments	3
Net Assets, Geographic Area \| Geographic Concentration Risk \| United States
Segment Reporting Information [Line Items]
Long-lived assets	99.00%

Revenue - Schedule of Regulated Operations Revenues: Natural Gas Distribution Segment (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Total Regulated operations revenues	$ 2,199,682	$ 1,521,790	$ 1,350,585
Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,940,084	1,497,750	1,339,151
Alternative revenue program revenues (deferrals)	(18,478)	13,181	12,140
Other revenues	13,463	10,859	(706)
Total Regulated operations revenues	1,935,069	1,521,790	1,350,585
Residential \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,324,794	1,035,612	958,520
Small commercial \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	378,520	270,214	221,541
Large commercial \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	85,234	57,371	44,633
Industrial/other \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	50,894	42,313	26,242
Transportation \| Southwest Gas Corporation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 100,642	$ 92,240	$ 88,215

Regulatory Assets and Liabilities (Tables)

12 Months Ended

Dec. 31, 2022

Regulated Operations [Abstract]

Schedule of Regulatory Assets

The following table represents existing regulatory assets and liabilities:


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.*				Southwest Gas Corporation
Regulatory assets:
Accrued pension and other postretirement benefit costs (1)	$	311,124	$	339,356	$	339,356
Deferred purchased gas costs (2)	450,120		291,145		291,145
Settled interest rate hedges (3)	—		31,278		—
Accrued purchased gas costs (4)	207,368		51,631		51,631
Unamortized premium on reacquired debt (5)	14,707		16,283		16,283
Accrued absence time (9)	17,854		16,975		16,975
Margin, interest- and tax-tracking (10)	21,024		22,709		22,709
Other (12)	65,981		62,233		60,798
	$	1,088,178	$	831,610	798,897
Regulatory liabilities:
Deferred purchased gas costs (2)	—		(5,736)		—
Accumulated removal costs (6)	(445,000)		(482,558)		(424,000)
Unamortized gain on reacquired debt (7)	(6,572)		(7,108)		(7,108)
Regulatory excess deferred/other taxes and gross-up (8)	(424,921)		(511,567)		(446,333)
Margin, interest- and property tax-tracking (10)	(10,920)		(8,523)		(8,523)
Unrecognized other postretirement benefit costs (11)	—		(17,815)		—
Other (12)	(5,393)		(10,321)		(8,573)
Net regulatory assets (liabilities)	$	195,372	$	(212,018)	$	(95,640)

(1)Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 11 - Pension and Other Postretirement Benefits).

(2)Balance recovered or refunded on an ongoing basis with interest.

(4)Included in Prepaid and other current assets on the Consolidated Balance Sheets. Balance recovered or refunded on an ongoing basis.

(5)Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments.

(7)Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets. Amortized over life of debt instruments.

(9)Regulatory recovery occurs on a one-year lag basis through the labor loading process. Included in Prepaid and other current assets on the Consolidated Balance Sheets.


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.				Southwest Gas Corporation
Other Regulatory Assets:
State mandated public purpose programs (including low income and conservation programs) (a) (e)	$	18,693	$	15,239	$	15,239
Infrastructure replacement programs and similar (b) (e)	8,533		6,545		6,545
Environmental compliance programs (c) (e)	5,803		6,807		6,807
Pension tracking mechanism (b)	13,098		10,281		10,281
Other (d)	19,854		23,361		21,926
	$	65,981	$	62,233	$	60,798

a)Included in Prepaid and other current assets on the Consolidated Balance Sheets.

b)Included in Deferred charges and other assets on the Consolidated Balance Sheets, except $930,000 which is included in Prepaid and other current assets in 2022.

e)Balance recovered or refunded on an ongoing basis, generally with interest.


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.				Southwest Gas Corporation
Other Regulatory Liabilities:
State mandated public purpose programs (including low income and conservation programs) (a) (c)	$	(1,567)	$	(1,886)	$	(1,886)
Environmental compliance programs (c) (d)	—		(4,182)		(4,182)

Other (b) (c)	(3,826)		(4,253)		(2,505)
	$	(5,393)	$	(10,321)	$	(8,573)

a)Included in Other current liabilities on the Consolidated Balance Sheets.

b)Included in Other current liabilities, except $823,000, in 2022, which is included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets.

c)Balance typically recovered or refunded on an ongoing basis, generally with interest.

d)In 2021, included in Other current liabilities on the Consolidated Balance Sheets.

Schedule of Regulatory Liabilities

The following table represents existing regulatory assets and liabilities:


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.*				Southwest Gas Corporation
Regulatory assets:
Accrued pension and other postretirement benefit costs (1)	$	311,124	$	339,356	$	339,356
Deferred purchased gas costs (2)	450,120		291,145		291,145
Settled interest rate hedges (3)	—		31,278		—
Accrued purchased gas costs (4)	207,368		51,631		51,631
Unamortized premium on reacquired debt (5)	14,707		16,283		16,283
Accrued absence time (9)	17,854		16,975		16,975
Margin, interest- and tax-tracking (10)	21,024		22,709		22,709
Other (12)	65,981		62,233		60,798
	$	1,088,178	$	831,610	798,897
Regulatory liabilities:
Deferred purchased gas costs (2)	—		(5,736)		—
Accumulated removal costs (6)	(445,000)		(482,558)		(424,000)
Unamortized gain on reacquired debt (7)	(6,572)		(7,108)		(7,108)
Regulatory excess deferred/other taxes and gross-up (8)	(424,921)		(511,567)		(446,333)
Margin, interest- and property tax-tracking (10)	(10,920)		(8,523)		(8,523)
Unrecognized other postretirement benefit costs (11)	—		(17,815)		—
Other (12)	(5,393)		(10,321)		(8,573)
Net regulatory assets (liabilities)	$	195,372	$	(212,018)	$	(95,640)

(1)Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovery period is greater than five years. (See Note 11 - Pension and Other Postretirement Benefits).

(2)Balance recovered or refunded on an ongoing basis with interest.

(4)Included in Prepaid and other current assets on the Consolidated Balance Sheets. Balance recovered or refunded on an ongoing basis.

(5)Included in Deferred charges and other assets on the Consolidated Balance Sheets. Recovered over life of debt instruments.

(7)Included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets. Amortized over life of debt instruments.

(9)Regulatory recovery occurs on a one-year lag basis through the labor loading process. Included in Prepaid and other current assets on the Consolidated Balance Sheets.


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.				Southwest Gas Corporation
Other Regulatory Assets:
State mandated public purpose programs (including low income and conservation programs) (a) (e)	$	18,693	$	15,239	$	15,239
Infrastructure replacement programs and similar (b) (e)	8,533		6,545		6,545
Environmental compliance programs (c) (e)	5,803		6,807		6,807
Pension tracking mechanism (b)	13,098		10,281		10,281
Other (d)	19,854		23,361		21,926
	$	65,981	$	62,233	$	60,798

a)Included in Prepaid and other current assets on the Consolidated Balance Sheets.

b)Included in Deferred charges and other assets on the Consolidated Balance Sheets, except $930,000 which is included in Prepaid and other current assets in 2022.

e)Balance recovered or refunded on an ongoing basis, generally with interest.


	December 31,
	2022		2021		2021
(Thousands of dollars)	Southwest Gas Holdings Inc.				Southwest Gas Corporation
Other Regulatory Liabilities:
State mandated public purpose programs (including low income and conservation programs) (a) (c)	$	(1,567)	$	(1,886)	$	(1,886)
Environmental compliance programs (c) (d)	—		(4,182)		(4,182)

Other (b) (c)	(3,826)		(4,253)		(2,505)
	$	(5,393)	$	(10,321)	$	(8,573)

a)Included in Other current liabilities on the Consolidated Balance Sheets.

b)Included in Other current liabilities, except $823,000, in 2022, which is included in Other deferred credits and other long-term liabilities on the Consolidated Balance Sheets.

c)Balance typically recovered or refunded on an ongoing basis, generally with interest.

d)In 2021, included in Other current liabilities on the Consolidated Balance Sheets.

Segment Information - Schedule of Segment Reporting Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 4,960,009	$ 3,680,451	$ 3,298,873
Interest income	16,183	5,113	4,015
Interest expense	242,750	119,198	111,477
Depreciation and amortization	470,455	371,041	332,027
Income tax expense (benefit)	(75,653)	39,648	65,753
Segment net income (loss)	(203,290)	200,779	232,324
Segment assets	13,196,614	12,765,257	8,735,853
Capital expenditures	859,421	715,626	825,105
Operating Segments
Segment Reporting Information [Line Items]
Revenues	4,825,351	3,578,105	3,164,014
Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenues	134,658	102,346	134,859
Interest income	0	0	0
Interest expense	47,314	639	1,060
Depreciation and amortization	0	0	0
Income tax expense (benefit)	(22,253)	(8,466)	(1,130)
Segment net income (loss)	(76,002)	(26,776)	(1,656)
Segment assets	7,312	47,664	3,980
Capital expenditures	0	0	0
Natural Gas Distribution
Segment Reporting Information [Line Items]
Revenues	1,935,069	1,521,790	1,350,585
Interest income	16,183	5,113	4,015
Interest expense	115,880	97,560	101,148
Depreciation and amortization	263,043	253,398	235,295
Income tax expense (benefit)	30,541	29,338	35,755
Segment net income (loss)	154,380	187,135	159,118
Segment assets	8,803,681	7,950,263	7,256,636
Capital expenditures	683,131	601,983	692,216
Natural Gas Distribution \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	1,935,069	1,521,790	1,350,585
Natural Gas Distribution \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenues	0	0	0
Utility Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	2,760,327	2,158,661	1,948,288
Interest income	0	0	0
Interest expense	61,371	20,999	9,269
Depreciation and amortization	155,353	117,643	96,732
Income tax expense (benefit)	5,727	18,776	31,128
Segment net income (loss)	2,065	40,420	74,862
Segment assets	2,642,272	2,579,748	1,475,237
Capital expenditures	130,166	113,643	132,889
Utility Infrastructure Services \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	2,625,669	2,056,315	1,813,429
Utility Infrastructure Services \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenues	134,658	102,346	$ 134,859
Pipeline and Storage
Segment Reporting Information [Line Items]
Revenues	264,613	0
Interest income	0	0
Interest expense	18,185	0
Depreciation and amortization	52,059	0
Income tax expense (benefit)	(89,668)	0
Segment net income (loss)	(283,733)	0
Segment assets	1,743,349	2,187,582
Capital expenditures	46,124	0
Pipeline and Storage \| Operating Segments
Segment Reporting Information [Line Items]
Revenues	264,613	0
Pipeline and Storage \| Segment Reconciling Items
Segment Reporting Information [Line Items]
Revenues	$ 0	$ 0

Share-Based Compensation - Schedule of Share-Based Plan Compensation Expense, Including Cash Award (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-Based Payment Arrangement [Abstract]
Share-based compensation plan expense, net of related tax benefits	$ 6,225	$ 5,747	$ 4,816
Share-based compensation plan related tax benefits	$ 1,966	$ 1,815	$ 1,521

Redeemable Noncontrolling Interests - Summary of Redeemable Noncontrolling Interest (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	$ 196,717	$ 165,716
Redeemable noncontrolling interest acquired		12,562
Net income attributable to redeemable noncontrolling interests	5,606	6,423
Redemption value adjustments	(3,325)	12,016
Redemption of equity interest from noncontrolling party	(39,649)
Ending balance	159,349	196,717
Linetec
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	184,148	165,716
Redeemable noncontrolling interest acquired		0
Net income attributable to redeemable noncontrolling interests	5,591	6,416
Redemption value adjustments	(3,325)	12,016
Redemption of equity interest from noncontrolling party	(39,649)
Ending balance	146,765	184,148
Drum
Stockholders' Equity Attributable to Noncontrolling Interest [Roll Forward]
Beginning balance	12,569	0
Redeemable noncontrolling interest acquired		12,562
Net income attributable to redeemable noncontrolling interests	15	7
Redemption value adjustments	0	0
Redemption of equity interest from noncontrolling party	0
Ending balance	$ 12,584	$ 12,569

Commitments and Contingencies (Details)	1 Months Ended	3 Months Ended
Commitments and Contingencies (Details)	Aug. 31, 2021 person	Jun. 30, 2022 USD ($)	Dec. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)
Loss Contingencies [Line Items]
Loss contingency, number of individuals injured \| person	4
Southwest Gas Corporation
Loss Contingencies [Line Items]
Self-insured retention amount associated with general liability claims			$ 1,000,000
Additional self-insured retention amount of general liability			4,000,000
Loss contingency, maximum			5,000,000
Loss contingency accrual				$ 5,000,000
Loss contingency recorded		$ 6,200,000
Centuri
Loss Contingencies [Line Items]
Self-insured retention amount associated with general liability claims			$ 750,000

Share-Based Compensation - Schedule of Nonvested Performance and Restricted Stock Unit Plans (Details) - Restricted Stock/Unit Plan - $ / shares	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Restricted Stock/ Units
Nonvested/unissued at beginning of year (in shares)	520,000
Granted (in shares)	279,000
Dividends (in shares)	10,000
Forfeited or expired (in shares)	(85,000)
Vested and issued (in shares)	(264,000)
Nonvested/unissued at year end (in shares)	460,000	520,000
Weighted- average grant date fair value
Beginning balance (in USD per share)	$ 61.01
Granted (in USD per share)	66.11	$ 65.38	$ 76.85
Dividends (in USD per share)	0
Forfeited or expired (in USD per share)	66.62
Vested and issued (in USD per share)	56.43
Ending balance (in USD per share)	$ 64.34	$ 61.01
Performance Shares
Restricted Stock/ Units
Granted (in shares)	167,200
Vested and issued (in shares)	(41,100)

Common Stock (Tables)

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Schedule of Common Stock Activity

The following table provides the life-to-date activity under that program through December 31, 2022:


Gross proceeds	$	158,180,343
Less: agent commissions	(1,581,803)
Net proceeds	$	156,598,540
Number of shares sold	2,302,407
Weighted average price per share	$	68.70

Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Related Tax Effects Allocated to OCI (Detail) - USD ($) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax	$ (3,034)
Other comprehensive income (loss), before tax	5,252	$ 18,732	$ (6,159)
Other comprehensive income (loss), tax	(2,733)	(4,490)	1,888
Total other comprehensive income (loss), net of tax	$ 2,519	$ 14,242	$ (4,271)
Effective income tax rate	27.70%	16.10%	21.60%	24.00%
Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax	$ 3,099
Other comprehensive income (loss), before tax	11,385	$ 18,712	$ (7,872)
Other comprehensive income (loss), tax	(2,733)	(4,490)	1,888
Total other comprehensive income (loss), net of tax	$ 8,652	$ 14,222	$ (5,984)
Effective income tax rate	16.50%	13.60%	18.30%	24.00%
Pension plans other comprehensive income (loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	$ 4,079
Other comprehensive income (loss) before reclassifications, tax	(980)
Other comprehensive income (loss) before reclassifications, net of tax	3,099
Other comprehensive income (loss), before tax	10,840
Other comprehensive income (loss), tax	(2,604)
Total other comprehensive income (loss), net of tax	8,236
Pension plans other comprehensive income (loss) \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	4,079
Other comprehensive income (loss) before reclassifications, tax	(980)
Other comprehensive income (loss) before reclassifications, net of tax	3,099
Other comprehensive income (loss), before tax	10,840	$ 16,538	$ (11,119)
Other comprehensive income (loss), tax	(2,604)	(3,968)	2,668
Total other comprehensive income (loss), net of tax	8,236	12,570	(8,451)
Net actuarial gain/(loss)
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	34,818
Other comprehensive income (loss), tax	(8,357)
Total other comprehensive income (loss), net of tax	26,461
Net actuarial gain/(loss) \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	4,079	59,176	(57,539)
Other comprehensive income (loss) before reclassifications, tax	(980)	(14,202)	13,809
Other comprehensive income (loss) before reclassifications, net of tax	3,099	44,974	(43,730)
Reclassification from AOCI, before Tax	34,818	44,597	37,830
Reclassification from AOCI, tax	(8,357)	(10,703)	(9,079)
Reclassification from AOCI, net of tax	26,461	33,894	28,751
Other comprehensive income (loss), before tax	34,818
Other comprehensive income (loss), tax	(8,357)
Total other comprehensive income (loss), net of tax	26,461
Amortization of prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	175
Other comprehensive income (loss), tax	(42)
Total other comprehensive income (loss), net of tax	133
Amortization of prior service cost \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	175	959	1,155
Reclassification from AOCI, tax	(42)	(230)	(277)
Reclassification from AOCI, net of tax	133	729	878
Other comprehensive income (loss), before tax	175
Other comprehensive income (loss), tax	(42)
Total other comprehensive income (loss), net of tax	133
Regulatory adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	(28,232)
Other comprehensive income (loss), tax	6,775
Total other comprehensive income (loss), net of tax	(21,457)
Regulatory adjustment \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	(28,232)	(88,194)	7,435
Reclassification from AOCI, tax	6,775	21,167	(1,785)
Reclassification from AOCI, net of tax	(21,457)	(67,027)	5,650
Other comprehensive income (loss), before tax	(28,232)
Other comprehensive income (loss), tax	6,775
Total other comprehensive income (loss), net of tax	(21,457)
FSIRS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	545
Reclassification from AOCI, tax	(129)
Reclassification from AOCI, net of tax	416
Other comprehensive income (loss), before tax	545
Other comprehensive income (loss), tax	(129)
Total other comprehensive income (loss), net of tax	416
FSIRS \| Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	545	2,174	3,247
Reclassification from AOCI, tax	(129)	(522)	(780)
Reclassification from AOCI, net of tax	416	1,652	2,467
Other comprehensive income (loss), before tax	545	2,174	3,247
Other comprehensive income (loss), tax	(129)	(522)	(780)
Total other comprehensive income (loss), net of tax	416	1,652	2,467
Foreign currency items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	(6,133)	20	1,713
Other comprehensive income (loss) before reclassifications, tax	0	0	0
Other comprehensive income (loss) before reclassifications, net of tax	$ (6,133)	$ 20	$ 1,713

Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - AOCI Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended			36 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent	$ 2,953,820
Other comprehensive income (loss) before reclassifications, net of tax	(3,034)
Other comprehensive income (loss), before tax	5,252	$ 18,732	$ (6,159)
Other comprehensive income (loss), tax	(2,733)	(4,490)	1,888
Total other comprehensive income (loss), net of tax	2,519	14,242	$ (4,271)
Ending balance, attributable to parent	$ 3,058,759	$ 2,953,820		$ 3,058,759
Effective income tax rate	27.70%	16.10%	21.60%	24.00%
Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	$ 2,527,937	$ 2,233,468
Beginning balance, attributable to parent	2,527,937
Other comprehensive income (loss) before reclassifications, net of tax	3,099
Other comprehensive income (loss), before tax	11,385	18,712	$ (7,872)
Other comprehensive income (loss), tax	(2,733)	(4,490)	1,888
Total other comprehensive income (loss), net of tax	8,652	14,222	(5,984)
Ending balance	2,569,175	2,527,937	$ 2,233,468	$ 2,569,175
Ending balance, attributable to parent	$ 2,569,175	$ 2,527,937		$ 2,569,175
Effective income tax rate	16.50%	13.60%	18.30%	24.00%
Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	$ (61,182)
Beginning balance, tax	14,685
Beginning balance	(46,497)
Other comprehensive income (loss) before reclassifications, before tax	4,079
Other comprehensive income (loss) before reclassifications, tax	(980)
Other comprehensive income (loss) before reclassifications, net of tax	3,099
Other comprehensive income (loss), before tax	10,840
Other comprehensive income (loss), tax	(2,604)
Total other comprehensive income (loss), net of tax	8,236
Ending balance, before tax	(50,342)	$ (61,182)		$ (50,342)
Ending balance, tax	12,081	14,685		12,081
Ending balance	(38,261)	(46,497)		(38,261)
Defined Benefit Plans \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent, before tax	(61,182)
Beginning balance, attributable to parent, tax	14,685
Beginning balance, attributable to parent	(46,497)
Other comprehensive income (loss) before reclassifications, before tax	4,079
Other comprehensive income (loss) before reclassifications, tax	(980)
Other comprehensive income (loss) before reclassifications, net of tax	3,099
Other comprehensive income (loss), before tax	10,840	16,538	$ (11,119)
Other comprehensive income (loss), tax	(2,604)	(3,968)	2,668
Total other comprehensive income (loss), net of tax	8,236	12,570	(8,451)
Ending balance, attributable to parent, before tax	(50,342)	(61,182)		(50,342)
Ending balance, attributable to parent, tax	12,081	14,685		12,081
Ending balance, attributable to parent	(38,261)	(46,497)		(38,261)
Amortization of prior service cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	175
Other comprehensive income (loss), tax	(42)
Total other comprehensive income (loss), net of tax	133
Amortization of prior service cost \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	175	959	1,155
Reclassification from AOCI, tax	(42)	(230)	(277)
Reclassification from AOCI, net of tax	133	729	878
Other comprehensive income (loss), before tax	175
Other comprehensive income (loss), tax	(42)
Total other comprehensive income (loss), net of tax	133
Amortization of net actuarial loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	34,818
Other comprehensive income (loss), tax	(8,357)
Total other comprehensive income (loss), net of tax	26,461
Amortization of net actuarial loss \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications, before tax	4,079	59,176	(57,539)
Other comprehensive income (loss) before reclassifications, tax	(980)	(14,202)	13,809
Other comprehensive income (loss) before reclassifications, net of tax	3,099	44,974	(43,730)
Reclassification from AOCI, before Tax	34,818	44,597	37,830
Reclassification from AOCI, tax	(8,357)	(10,703)	(9,079)
Reclassification from AOCI, net of tax	26,461	33,894	28,751
Other comprehensive income (loss), before tax	34,818
Other comprehensive income (loss), tax	(8,357)
Total other comprehensive income (loss), net of tax	26,461
Regulatory adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	(28,232)
Other comprehensive income (loss), tax	6,775
Total other comprehensive income (loss), net of tax	(21,457)
Regulatory adjustment \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	(28,232)	(88,194)	7,435
Reclassification from AOCI, tax	6,775	21,167	(1,785)
Reclassification from AOCI, net of tax	(21,457)	(67,027)	5,650
Other comprehensive income (loss), before tax	(28,232)
Other comprehensive income (loss), tax	6,775
Total other comprehensive income (loss), net of tax	(21,457)
FSIRS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	(545)
Beginning balance, tax	129
Beginning balance	(416)
Reclassification from AOCI, before Tax	545
Reclassification from AOCI, tax	(129)
Reclassification from AOCI, net of tax	416
Other comprehensive income (loss), before tax	545
Other comprehensive income (loss), tax	(129)
Total other comprehensive income (loss), net of tax	416
Ending balance, before tax	0	(545)		0
Ending balance, tax	0	129		0
Ending balance	0	(416)		0
FSIRS \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent, before tax	(545)
Beginning balance, attributable to parent, tax	129
Beginning balance, attributable to parent	(416)
Reclassification from AOCI, before Tax	545	2,174	3,247
Reclassification from AOCI, tax	(129)	(522)	(780)
Reclassification from AOCI, net of tax	416	1,652	2,467
Other comprehensive income (loss), before tax	545	2,174	3,247
Other comprehensive income (loss), tax	(129)	(522)	(780)
Total other comprehensive income (loss), net of tax	416	1,652	2,467
Ending balance, attributable to parent, before tax	0	(545)		0
Ending balance, attributable to parent, tax	0	129		0
Ending balance, attributable to parent	0	(416)		0
Foreign Currency Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	152
Beginning balance	152
Other comprehensive income (loss) before reclassifications, before tax	(6,133)
Other comprehensive income (loss) before reclassifications, net of tax	(6,133)
Ending balance, before tax	(5,981)	152		(5,981)
Ending balance	(5,981)	152		(5,981)
AOCI Including Portion Attributable to Noncontrolling Interest
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications, net of tax	2,519
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(46,761)	(61,003)	(56,732)	(56,732)
Ending balance	(44,242)	(46,761)	(61,003)	(44,242)
AOCI Attributable to Parent \| Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(46,913)	(61,135)	(55,151)	(55,151)
Beginning balance, attributable to parent	(46,913)
Ending balance	(38,261)	(46,913)	$ (61,135)	(38,261)
Ending balance, attributable to parent	$ (38,261)	$ (46,913)		$ (38,261)

Background, Organization, and Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Other Property and Investments

Other property and investments on Southwest’s and the Company’s Consolidated Balance Sheets includes:


	December 31,
(Thousands of dollars)	2022		2021
Net cash surrender value of COLI policies	$	136,245	$	149,947
Other property	33,152		3,146
Total Southwest Gas Corporation	169,397		153,093
Non-regulated property, equipment, and intangibles	1,677,218		1,616,392
Non-regulated accumulated provision for depreciation and amortization	(596,518)		(512,343)
Other property and investments	31,075		59,337
Total Southwest Gas Holdings, Inc.	$	1,281,172	$	1,316,479

Summary of Intangible Assets

Centuri’s intangible assets (other than goodwill) have finite lives and are associated with businesses previously acquired. The balances at December 31, 2022 and 2021, respectively, were as follows:


	December 31, 2022
(Thousands of dollars)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Customer relationships	$	391,758	$	(63,509)	$	328,249
Trade names and trademarks	79,277		(12,278)		66,999

Total	$	471,035	$	(75,787)	$	395,248

	December 31, 2021
Customer relationships	$	393,834	$	(42,886)	$	350,948
Trade names and trademarks	79,650		(7,093)		72,557
Customer contracts backlog	4,500		(1,500)		3,000
Total	$	477,984	$	(51,479)	$	426,505

Schedule of Estimated Future Amortization of Intangible Assets

The estimated future amortization of the intangible assets for the next five years and thereafter is as follows:


(Thousands of dollars)
2023	$	26,690
2024	26,690
2025	26,678
2026	26,455
2027	26,088
Thereafter	262,647
Total	$	395,248

Schedule of Goodwill

Goodwill in the Natural Gas Distribution and Utility Infrastructure Services segments is included in their respective Consolidated Balance Sheets as follows:


(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Total Company
Balance, December 31, 2020	$	10,095	$	335,089	$	345,184
Additional goodwill from Riggs Distler acquisition	—		449,501		449,501
Foreign currency translation adjustment	—		468		468
Balance, December 31, 2021	10,095		785,058		$	795,153
Additional goodwill from Graham County acquisition	1,060		—		1,060
Measurement-period adjustments from Riggs Distler acquisition	—		(1,924)		(1,924)
Foreign currency translation adjustment	—		(7,039)		(7,039)
Balance, December 31, 2022	$	11,155	$	776,095	$	787,250

Schedule of Capitalized and Debt Portion of AFUDC

Regulated operations plant construction costs, including AFUDC, are recoverable as part of authorized rates through depreciation when completed projects are placed into operation, and general rate relief is requested and granted. AFUDC, disaggregated by type, included in the Company’s and Southwest’s Consolidated Statements of Income are presented in the table below:


(Thousands of dollars)	2022			2021			2020
AFUDC:
Debt portion	$	3,535		$	1,046		$	3,202
Equity portion	—			—			4,724
AFUDC capitalized as part of regulated operations plant	$	3,535		$	1,046		$	7,926
AFUDC rate	2.64		%	0.96		%	5.51		%

Schedule of Other Income (Deductions)

The following table provides the composition of significant items included in Other income (deductions) on the Consolidated Statements of Income:


(Thousands of dollars)	2022		2021		2020
Southwest Gas Corporation:
Change in COLI policies	$	(5,400)	$	8,800	$	9,200
Interest income	16,183		5,113		4,015
Equity AFUDC	—		—		4,724
Other components of net periodic benefit cost	(751)		(14,021)		(20,022)
Miscellaneous income and (expense)	(16,916)		(4,451)		(4,507)
Southwest Gas Corporation – total other income (deductions)	(6,884)		(4,559)		(6,590)
Centuri, MountainWest, and Southwest Gas Holdings, Inc.:

Foreign transaction gain (loss)	977		(22)		(16)
Equity AFUDC	465		—		—
Equity in earnings of unconsolidated investments	2,629		226		80
Miscellaneous income and (expense)	(3,113)		863		(271)
Corporate and administrative	(263)		$	(7)	$	8
Southwest Gas Holdings, Inc. - total other income (deductions)	$	(6,189)	$	(3,499)	$	(6,789)

Schedule of Earnings Per Share, Basic and Diluted

A reconciliation of the denominator used in Basic and Diluted EPS calculations is shown in the following table:


(In thousands)	2022	2021	2020
Weighted average basic shares	65,558	59,145	55,998
Effect of dilutive securities:
Restricted stock units (1)(2)	—	114	78
Weighted average diluted shares	65,558	59,259	56,076

(1) The number of anti-dilutive restricted stock units for 2022 excluded from the calculation of diluted shares is 157,000.

(2) The number of securities granted for 2022, 2021, and 2020 includes 144,000, 104,000, and 69,000 performance shares, respectively, the total of which was derived by assuming that target performance will be achieved during the relevant performance period.

- Definition

Tabular disclosure of goodwill by reportable segment and in total which includes a rollforward schedule.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (h)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (c)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 3: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (g)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 4: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 5: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (e)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 6: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 7: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1A
-URI https://asc.fasb.org/extlink&oid=121556970&loc=SL108378252-109267

Reference 8: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (f)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 9: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (a)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 2
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13854-109267

Reference 11: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 55
-Paragraph 24
-URI https://asc.fasb.org/extlink&oid=122137925&loc=d3e14258-109268

Reference 12: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI https://asc.fasb.org/extlink&oid=121556970&loc=d3e13816-109267

+ Details

Debt - Narrative (Details)		1 Months Ended				12 Months Ended
Debt - Narrative (Details)	Nov. 04, 2022 USD ($)	Jan. 31, 2023 USD ($)	Mar. 31, 2022 USD ($)	Dec. 31, 2021 USD ($)	Nov. 30, 2021	Dec. 31, 2022 USD ($)	Sep. 30, 2023	Jun. 30, 2023	Mar. 31, 2023	Dec. 30, 2022 USD ($)	Dec. 29, 2022 USD ($)	Nov. 03, 2022 USD ($)	Sep. 26, 2022 USD ($)	Aug. 27, 2021 USD ($)
Debt Instrument [Line Items]
Long-term debt outstanding						$ 726,412,000
Short-term debt				$ 1,909,000,000		1,542,806,000
Centuri secured term loan facility
Debt Instrument [Line Items]
Borrowings outstanding under facility						1,009,000,000.000
Term Loan Facility due December 30, 2022 \| Loans Payable
Debt Instrument [Line Items]
Debt instrument, term					364 days
Term Loan Facility Due December 30, 2023 \| Loans Payable
Debt Instrument [Line Items]
Borrowings outstanding under facility						1,150,000,000
Debt instrument face amount													$ 1,600,000,000
Debt covenant, additional debt amount could be issued						1,200,000,000
Short-term debt						$ 72,000,000
Weighted average interest rate						6.423%
Debt instrument, term					364 days
Repayments of debt						$ 1,075,000,000.000
Change intervals of basis spread on variable rate						0.25%
Debt term, mandatory prepayment as percentage of cash proceeds received					100.00%
Debt term, percentage of committed amount under specific acquisition financings					100.00%
Loans Payable \| Term Loan Facility Due December 30, 2023 \| Forecast
Debt Instrument [Line Items]
Lenders fees, percentage of outstanding principal balance							0.20%	0.15%	0.10%
Minimum \| Term Loan Facility Due December 30, 2023 \| Loans Payable
Debt Instrument [Line Items]
Commitment fee percentage					0.06%
Maximum \| Term Loan Facility Due December 30, 2023 \| Loans Payable
Debt Instrument [Line Items]
Commitment fee percentage					0.175%
SOFR \| Minimum \| Term Loan Facility Due December 30, 2023 \| Loans Payable
Debt Instrument [Line Items]
Debt, basis spread on variable rate					1.50%
SOFR \| Maximum \| Term Loan Facility Due December 30, 2023 \| Loans Payable
Debt Instrument [Line Items]
Debt, basis spread on variable rate					2.25%
Alternative Base Rate \| Minimum \| Term Loan Facility Due December 30, 2023 \| Loans Payable
Debt Instrument [Line Items]
Debt, basis spread on variable rate					0.50%
Alternative Base Rate \| Maximum \| Term Loan Facility Due December 30, 2023 \| Loans Payable
Debt Instrument [Line Items]
Debt, basis spread on variable rate					1.25%
$300 Million Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity										$ 300,000,000
Line of credit facility, maximum commitment amount						$ 300,000,000
Short-term debt				$ 59,000,000		$ 173,000,000
Weighted average interest rate				1.323%		5.588%
$300 Million Credit Facility \| SOFR
Debt Instrument [Line Items]
Debt, basis spread on variable rate						1.25%
$300 Million Credit Facility \| Alternative Base Rate
Debt Instrument [Line Items]
Debt, basis spread on variable rate						0.25%
$200 Million Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity											$ 200,000,000
Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt outstanding						$ 457,500,000
Debt covenant, additional debt amount could be issued						2,500,000,000
Debt covenant, equity cushion relating to minimum net worth requirement						2,000,000,000
Short-term debt				$ 250,000,000		$ 225,000,000
Southwest Gas Corporation \| $250 Million Term Loan (March 2021 Term Loan)
Debt Instrument [Line Items]
Debt covenant, ratio of funded debt to total capitalization						0.70
Debt instrument face amount			$ 250,000,000
Short-term debt						$ 225,000,000
Weighted average interest rate						5.173%
Southwest Gas Corporation \| $450 Million Term Loan \| Subsequent Event
Debt Instrument [Line Items]
Debt covenant, ratio of funded debt to total capitalization		0.70
Debt instrument face amount		$ 450,000,000
Debt instrument, term		364 days
Southwest Gas Corporation \| Debentures
Debt Instrument [Line Items]
Long-term debt outstanding						$ 407,500,000
Southwest Gas Corporation \| Debentures \| Notes, 4.05%, due 2032
Debt Instrument [Line Items]
Debt instrument face amount			$ 600,000,000
Debt instrument interest rate			4.05%			4.05%
Debt instrument discount rate			0.65%
Southwest Gas Corporation \| Debentures \| Notes, 3.875%, due 2022
Debt Instrument [Line Items]
Debt instrument face amount			$ 250,000,000
Debt instrument interest rate			3.875%	3.875%
Southwest Gas Corporation \| Debentures \| Notes, 6.1%, due 2041
Debt Instrument [Line Items]
Debt instrument interest rate						6.10%
Southwest Gas Corporation \| SOFR \| $450 Million Term Loan \| Subsequent Event
Debt Instrument [Line Items]
Debt, basis spread on variable rate		0.95%
Debt interest adjustment rate		0.10%
Southwest Gas Corporation \| SOFR \| Minimum \| $250 Million Term Loan (March 2021 Term Loan)
Debt Instrument [Line Items]
Debt, basis spread on variable rate			0.55%
Southwest Gas Corporation \| SOFR \| Maximum \| $250 Million Term Loan (March 2021 Term Loan)
Debt Instrument [Line Items]
Debt, basis spread on variable rate			1.00%
Southwest Gas Corporation \| Alternative Base Rate \| $250 Million Term Loan (March 2021 Term Loan)
Debt Instrument [Line Items]
Debt, basis spread on variable rate			0.00%
Southwest Gas Corporation \| Alternative Base Rate \| $450 Million Term Loan \| Subsequent Event
Debt Instrument [Line Items]
Debt, basis spread on variable rate		0.00%
Southwest Gas Corporation \| $400 Million Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity						$ 400,000,000
Line of credit designated as long term debt						150,000,000
Line of credit designated for working capital purposes						$ 250,000,000
Debt covenant, ratio of funded debt to total capitalization						0.70
Long-term debt outstanding						$ 50,000,000
Effective interest rates						5.88%
Short-term debt				$ 0		$ 0
Southwest Gas Corporation \| $400 Million Credit Facility \| Minimum
Debt Instrument [Line Items]
Commitment fee percentage				0.075%
Southwest Gas Corporation \| $400 Million Credit Facility \| Maximum
Debt Instrument [Line Items]
Commitment fee percentage				0.20%
Southwest Gas Corporation \| $400 Million Credit Facility \| SOFR
Debt Instrument [Line Items]
Debt, basis spread on variable rate						1.125%
Southwest Gas Corporation \| $400 Million Credit Facility \| SOFR \| Minimum
Debt Instrument [Line Items]
Debt, basis spread on variable rate				0.75%
Southwest Gas Corporation \| $400 Million Credit Facility \| SOFR \| Maximum
Debt Instrument [Line Items]
Debt, basis spread on variable rate				1.50%
Southwest Gas Corporation \| $400 Million Credit Facility \| Alternative Base Rate
Debt Instrument [Line Items]
Debt, basis spread on variable rate						0.125%
Southwest Gas Corporation \| $400 Million Credit Facility \| Alternative Base Rate \| Minimum
Debt Instrument [Line Items]
Debt, basis spread on variable rate				0.00%
Southwest Gas Corporation \| $400 Million Credit Facility \| Alternative Base Rate \| Maximum
Debt Instrument [Line Items]
Debt, basis spread on variable rate				0.50%
Southwest Gas Corporation \| Commercial Paper Program
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity						$ 50,000,000
Borrowings outstanding under facility						0
Centuri
Debt Instrument [Line Items]
Debt covenant, additional debt amount could be issued						222,000,000
Debt covenant, equity cushion relating to minimum fixed charge ratio coverage requirement						$ 33,000,000
Debt covenant, dividend restriction calculation, percentage of net income						50.00%
Debt covenant, dividend restriction calculation, period						12 months
Centuri \| Centuri Secured Term Loan Facility And Revolving Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity						$ 1,545,000,000
Borrowings outstanding under facility						$ 1,091,000,000.000
Effective interest rates						7.20%
Centuri \| Centuri secured term loan facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity														$ 1,145,000,000
Centuri \| Minimum \| Centuri Secured Term Loan Facility And Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage						0.15%
Centuri \| Maximum \| Centuri Secured Term Loan Facility And Revolving Credit Facility
Debt Instrument [Line Items]
Commitment fee percentage						0.35%
Centuri \| Alternative Base Rate \| Centuri secured term loan facility
Debt Instrument [Line Items]
Debt, basis spread on variable rate						1.50%
Centuri \| LIBOR \| Centuri secured term loan facility
Debt Instrument [Line Items]
Debt, basis spread on variable rate						2.50%
Debt floor interest rate						0.50%
Centuri \| Revolving Credit Facility \| Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity														$ 400,000,000
Debt covenant, minimum interest coverage ratio						2.50
Debt secured by assets						$ 2,500,000,000
Centuri \| Revolving Credit Facility \| Line of Credit \| From December 31, 2022 through June 30, 2023
Debt Instrument [Line Items]
Debt covenant, net leverage ratio						6.00
Centuri \| Revolving Credit Facility \| Line of Credit \| From July 1, 2023 through September 30, 2023
Debt Instrument [Line Items]
Debt covenant, net leverage ratio						5.50
Centuri \| Revolving Credit Facility \| Line of Credit \| From October 1, 2023 through December 31, 2023
Debt Instrument [Line Items]
Debt covenant, net leverage ratio						4.50
Centuri \| Revolving Credit Facility \| Line of Credit \| From January 1, 2024 and thereafter
Debt Instrument [Line Items]
Debt covenant, net leverage ratio						4.00
Centuri \| Revolving Credit Facility \| SOFR \| Minimum
Debt Instrument [Line Items]
Debt, basis spread on variable rate	1.00%
Centuri \| Revolving Credit Facility \| SOFR \| Maximum
Debt Instrument [Line Items]
Debt, basis spread on variable rate	2.50%
Centuri \| Revolving Credit Facility \| CDOR \| Minimum
Debt Instrument [Line Items]
Debt, basis spread on variable rate	0.00%
Centuri \| Revolving Credit Facility \| CDOR \| Maximum
Debt Instrument [Line Items]
Debt, basis spread on variable rate	1.50%
Centuri \| Letter of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 125,000,000											$ 100,000,000

Regulated Operations Plant and Leases - Schedule of Depreciation and Amortization Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 470,455	$ 371,041	$ 332,027
Gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Depreciation and amortization expense	$ 243,857	$ 230,245	$ 215,636

CONSOLIDATED STATEMENTS OF CASH FLOWS - Southwest - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$ (197,684)	$ 207,202	$ 238,985
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	470,455	371,041	332,027
Deferred income taxes	(72,048)	61,212	50,717
Gain on sale of property	(7,865)	(6,906)	(1,848)
Changes in undistributed stock compensation	9,446	9,294	7,114
Equity AFUDC	(465)	0	(4,724)
Changes in current assets and liabilities:
Accounts receivable, net of allowances	(193,775)	(51,554)	(48,772)
Accrued utility revenue	(3,200)	(2,500)	(3,300)
Deferred purchased gas costs	(147,215)	(343,728)	36,239
Accounts payable	293,909	50,426	(7,694)
Accrued taxes	17,929	(6,725)	15,171
Other current assets and liabilities	(207,853)	(89,209)	107,427
Changes in deferred charges and other assets	16,886	(13,541)	(32,591)
Changes in other liabilities and deferred credits	(26,485)	(73,629)	(62,671)
Net cash provided by operating activities	407,460	111,383	626,080
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(859,421)	(715,626)	(825,105)
Changes in customer advances	21,506	15,974	14,033
Other	17,822	18,256	9,003
Net cash used in investing activities	(838,902)	(3,035,656)	(802,069)
CASH FLOW FROM FINANCING ACTIVITIES:
Dividends paid	(160,563)	(138,222)	(125,504)
Issuance of long-term debt, net	1,067,805	1,660,696	662,377
Retirement of long-term debt	(499,914)	(452,664)	(356,406)
Change in credit facility and commercial paper	(80,000)	(20,000)	0
Withholding remittance – share-based compensation	(2,662)	(1,264)	(2,736)
Other, including principal payments on finance leases	(24,172)	(729)	(3,402)
Net cash provided by financing activities	356,480	3,063,458	209,574
Change in cash and cash equivalents	(75,816)	139,345	33,813
Cash and cash equivalents at beginning of period	222,697	83,352	49,539
Cash and cash equivalents at end of period	123,078	222,697	83,352
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	219,825	104,352	105,182
Income taxes paid (received), net	12,001	4,208	(10,951)
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	154,380	187,135	159,118
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	263,043	253,398	235,295
Deferred income taxes	42,387	53,237	44,997
Gain on sale of property	(1,503)	0	0
Changes in undistributed stock compensation	5,776	6,392	5,294
Equity AFUDC	0	0	(4,724)
Changes in current assets and liabilities:
Accounts receivable, net of allowances	(64,414)	(22,806)	3,933
Accrued utility revenue	(3,200)	(2,500)	(3,300)
Deferred purchased gas costs	(158,975)	(343,728)	36,239
Accounts payable	243,276	57,764	9,618
Accrued taxes	21,754	7,753	(1,527)
Other current assets and liabilities	(188,737)	(70,271)	48,545
Changes in deferred charges and other assets	(1,694)	(28,743)	(44,291)
Changes in other liabilities and deferred credits	(27,690)	(72,386)	(65,136)
Net cash provided by operating activities	284,403	25,245	424,061
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(683,131)	(601,983)	(692,216)
Changes in customer advances	21,506	15,973	14,033
Other	6,917	(32)	771
Net cash used in investing activities	(654,708)	(586,042)	(677,412)
CASH FLOW FROM FINANCING ACTIVITIES:
Contributions from parent	0	202,583	177,922
Dividends paid	(122,200)	(111,400)	(104,500)
Issuance of long-term debt, net	891,663	297,318	446,508
Retirement of long-term debt	(275,000)	0	(125,000)
Change in credit facility and commercial paper	(80,000)	(20,000)	0
Change in short-term debt	(25,000)	193,000	(137,000)
Withholding remittance – share-based compensation	(2,569)	(1,263)	(2,736)
Other, including principal payments on finance leases	(3,457)	(1,820)	(1,262)
Net cash provided by financing activities	383,437	558,418	253,932
Change in cash and cash equivalents	13,132	(2,379)	581
Cash and cash equivalents at beginning of period	38,691	41,070	40,489
Cash and cash equivalents at end of period	51,823	38,691	41,070
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	107,980	90,240	96,726
Income taxes paid (received), net	$ 5	$ (13,529)	$ (19,603)

CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
CASH FLOW FROM OPERATING ACTIVITIES:
Net income (loss)	$ (197,684)	$ 207,202	$ 238,985
Adjustments to reconcile net income (loss) to net cash provided by operating activities:
Depreciation and amortization	470,455	371,041	332,027
Impairment of assets and other charges	455,425	0	0
Deferred income taxes	(72,048)	61,212	50,717
Gains on sale of property and equipment	(7,865)	(6,906)	(1,848)
Changes in undistributed stock compensation	9,446	9,294	7,114
Equity AFUDC	(465)	0	(4,724)
Changes in current assets and liabilities:
Accounts receivable, net of allowances	(193,775)	(51,554)	(48,772)
Accrued utility revenue	(3,200)	(2,500)	(3,300)
Deferred purchased gas costs	(147,215)	(343,728)	36,239
Accounts payable	293,909	50,426	(7,694)
Accrued taxes	17,929	(6,725)	15,171
Other current assets and liabilities	(207,853)	(89,209)	107,427
Changes in deferred charges and other assets	16,886	(13,541)	(32,591)
Changes in other liabilities and deferred credits	(26,485)	(73,629)	(62,671)
Net cash provided by operating activities	407,460	111,383	626,080
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(859,421)	(715,626)	(825,105)
Acquisition of businesses, net of cash acquired	(18,809)	(2,354,260)	0
Changes in customer advances	21,506	15,974	14,033
Other	17,822	18,256	9,003
Net cash used in investing activities	(838,902)	(3,035,656)	(802,069)
CASH FLOW FROM FINANCING ACTIVITIES:
Issuance of common stock, net	461,828	213,641	139,245
Dividends paid	(160,563)	(138,222)	(125,504)
Centuri distribution to redeemable noncontrolling interest	(39,649)	0	0
Issuance of long-term debt, net	1,067,805	1,660,696	662,377
Retirement of long-term debt	(499,914)	(452,664)	(356,406)
Change in credit facility and commercial paper	(80,000)	(20,000)	0
Change in short-term debt	(366,193)	(48,000)	(104,000)
Issuance of short-term debt	0	1,850,000	0
Withholding remittance – share-based compensation	(2,662)	(1,264)	(2,736)
Other, including principal payments on finance leases	(24,172)	(729)	(3,402)
Net cash provided by financing activities	356,480	3,063,458	209,574
Effects of currency translation on cash and cash equivalents	(854)	160	228
Change in cash and cash equivalents	(75,816)	139,345	33,813
Cash and cash equivalents disposed	(23,803)	0	0
Cash and cash equivalents at beginning of period	222,697	83,352	49,539
Cash and cash equivalents at end of period	123,078	222,697	83,352
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	219,825	104,352	105,182
Income taxes paid (received), net	$ 12,001	$ 4,208	$ (10,951)

Share-Based Compensation (Tables)

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Schedule of Share-Based Plan Compensation Expense, Including Cash Award

The table below shows total share-based plan compensation expense which was recognized in the Consolidated Statements of Income:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Share-based compensation plan expense, net of related tax benefits	$	6,225	$	5,747	$	4,816
Share-based compensation plan related tax benefits	1,966		1,815		1,521

Schedule of Nonvested Performance and Restricted Stock Unit Plans

The following table summarizes the activity of the restricted stock/units programs as of December 31, 2022:


(Thousands of shares)	Restricted Stock/ Units (1)	Weighted- average grant date fair value
Nonvested/unissued at December 31, 2021	520	$	61.01
Granted	279	66.11
Dividends	10	—
Forfeited or expired	(85)	66.62
Vested and issued (2)	(264)	56.43
Nonvested/unissued at December 31, 2022	460	$	64.34

(1)The number of performance shares includes 167,200 granted and 41,100 vested and issued, which was derived by assuming that target performance will be achieved during the relevant performance period.

(2)Includes shares for retiree payouts and those converted for taxes.

CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Regulated operations plant:
Gas plant	$ 9,453,907	$ 10,789,690
Less: accumulated depreciation	(2,674,157)	(3,397,736)
Construction work in progress	244,750	202,068
Net regulated operations plant	7,024,500	7,594,022
Other property and investments, net	1,281,172	1,316,479
Current assets:
Cash and cash equivalents	123,078	222,697
Accounts receivable, net of allowances	866,246	707,127
Accrued utility revenue	88,100	84,900
Income taxes receivable, net	8,738	16,816
Deferred purchased gas costs	450,120	291,145
Prepaid and other current assets	433,850	292,082
Current assets held for sale	1,737,530	0
Total current assets	3,707,662	1,614,767
Noncurrent assets:
Goodwill	787,250	1,781,332
Deferred income taxes	82	121
Deferred charges and other assets	395,948	458,536
Total noncurrent assets	1,183,280	2,239,989
Total assets	13,196,614	12,765,257
Capitalization:
Common stock	68,749	62,052
Additional paid-in capital	2,287,183	1,824,216
Accumulated other comprehensive loss, net	(44,242)	(46,761)
Retained earnings	747,069	1,114,313
Total Southwest Gas Holdings, Inc. equity	3,058,759	2,953,820
Redeemable noncontrolling interests	159,349	196,717
Long-term debt, less current maturities	4,403,299	4,115,684
Total capitalization	7,621,407	7,266,221
Commitments and contingencies (Note 10)
Current liabilities:
Current maturities of long-term debt	44,557	297,324
Short-term debt	1,542,806	1,909,000
Accounts payable	662,090	353,365
Customer deposits	51,182	59,327
Income taxes payable, net	2,690	6,734
Accrued general taxes	67,094	53,473
Accrued interest	38,556	30,964
Deferred purchased gas costs	0	5,736
Other current liabilities	369,743	396,126
Current liabilities held for sale	644,245	0
Total current liabilities	3,422,963	3,112,049
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	682,067	768,868
Accumulated removal costs	445,000	480,583
Other deferred credits and other long-term liabilities	1,025,177	1,137,536
Total deferred income taxes and other credits	2,152,244	2,386,987
Total capitalization and liabilities	$ 13,196,614	$ 12,765,257

Income Taxes - Narrative (Details) - USD ($)	12 Months Ended
Income Taxes - Narrative (Details) - USD ($)	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Income Tax Disclosure [Line Items]
Deferred income taxes	$ 82,000	$ 121,000
Unrecognized tax benefits that, if recognized, would affect the effective tax rate	3,100,000
Tax-related interest income	0	$ 21,000	$ 523,000
General Business Tax Credit Carryforward
Income Tax Disclosure [Line Items]
Tax credit carryforward	4,000,000
Capital Loss Carryforward
Income Tax Disclosure [Line Items]
Tax credit carryforward	0
Federal
Income Tax Disclosure [Line Items]
Operating loss carryforward	932,800,000
Foreign
Income Tax Disclosure [Line Items]
Operating loss carryforward	21,200,000
State
Income Tax Disclosure [Line Items]
Operating loss carryforward	519,000,000
Southwest Gas Corporation
Income Tax Disclosure [Line Items]
Unrecognized tax benefits that, if recognized, would affect the effective tax rate	$ 2,600,000

Acquisitions and Dispositions - Schedule of Assets Held for Sale (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Current assets held for sale	$ 1,737,530	$ 0
Total current liabilities, held for sale	644,245	$ 0
MountainWest \| Disposal Group, Held-for-sale, Not Discontinued Operations
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Regulated operations plant, net of accumulated depreciation of $907 million	957,729
Regulated operations plant, accumulated depreciation	907,000
Other property and investments	49,546
Other current assets	188,629
Goodwill, net of accumulated impairment of $449.6 million	508,395
Goodwill impairment loss	449,600
Deferred charges and other assets	39,050
Total assets	1,743,349
Disposal selling costs	5,819
Other current liabilities	55,188
Long-term debt	448,862
Other deferred credits and liabilities	140,195
Total current liabilities, held for sale	644,245
Cash and cash equivalents disposed	23,800
Regulatory assets disposed	2,200
In-kind system gas imbalance disposed	116,600
Regulatory assets, included in deferred charges and other assets	30,100
Liabilities disposed related to regulatory excess deferred/other taxes and gross-up	60,200
Liabilities disposed related to accumulated removal costs	58,800
MountainWest \| Disposal Group, Held-for-sale, Not Discontinued Operations \| Other current liabilities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Regulatory liabilities	18,900
MountainWest \| Disposal Group, Held-for-sale, Not Discontinued Operations \| Other Deferred Credits And Liabilities
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Regulatory liabilities	$ 139,000

Share-Based Compensation

12 Months Ended

Dec. 31, 2022

Share-Based Payment Arrangement [Abstract]

Share-Based Compensation

Note 9 - Share-Based Compensation

At December 31, 2022, the following share-based compensation plans existed at the Company: an omnibus incentive plan and a restricted stock/unit plan. The fair value of share grants is primarily based on the closing price of the Company’s stock on the date of grant. All share grants in 2022, including time-lapse restricted stock units and performance shares, occurred under the omnibus incentive plan. The table below shows total share-based plan compensation expense which was recognized in the Consolidated Statements of Income:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Share-based compensation plan expense, net of related tax benefits	$	6,225	$	5,747	$	4,816
Share-based compensation plan related tax benefits	1,966		1,815		1,521

Omnibus Incentive Plan

The omnibus incentive plan is used to promote the long-term growth and profitability of the Company, including its subsidiaries, by providing directors, employees, and certain other individuals with incentives to increase stockholder value and otherwise contribute to the success of the Company. In addition, the plan enables the Company to attract, retain, and reward the best available persons for positions of responsibility. The omnibus incentive plan provides for the grant of stock options, stock appreciation rights, restricted stock, restricted stock units, performance shares, and other equity-based and cash awards. Employees, directors, and consultants who provide services to the Company or any subsidiary may be eligible under this plan. For grants under the omnibus incentive plan, directors continue to immediately vest in the shares upon grant but are provided the option to defer receipt of equity compensation until they leave the Board of Directors.

Performance-based incentive opportunities under the omnibus plan were granted to all officers of Southwest in the form of performance shares and are based, depending on the officer, on consolidated earnings per share, utility net income, and utility return on equity, with an adjustment based on relative total shareholder return, in each case, measured over a three-year

performance period. Like other restricted stock/unit programs, shares are restricted based on vesting, and in this case, further subject to future performance determinations against relevant benchmarks. Southwest recorded $2.1 million, $3.4 million, and $2.8 million of estimated compensation expense associated with these shares during 2022, 2021, and 2020, respectively.

Restricted Stock/Units

Restricted stock/units under the restricted stock/unit plan were previously granted to attract, motivate, retain, and reward key employees of the Company with an incentive to attain high levels of individual performance and improved financial performance. The legacy plan was also established to attract, motivate, and retain experienced and knowledgeable directors. As noted above, grants of restricted stock during 2022, were granted under the omnibus incentive plan. All remaining shares under the legacy restricted stock/unit plan (in regard to employees) were issued during 2021; remaining unissued legacy program shares relate solely to directors, and such shares were immediately vested at the time of grant, with distribution to occur when service on the Board ends. No new grants are made under the legacy plan, as all future stock-based incentive compensation, including with regard to restricted stock, is granted under programs of the omnibus incentive plan, which for directors, with advance election, issuance may occur upon grant. Conversely, with regard to management, grants under the omnibus plan are of time-lapse character, with graded vesting (and issuance in the form of common stock) occurring, 40% at the end of year one and 30% at the end of years two and three.

The following table summarizes the activity of the restricted stock/units programs as of December 31, 2022:


(Thousands of shares)	Restricted Stock/ Units (1)	Weighted- average grant date fair value
Nonvested/unissued at December 31, 2021	520	$	61.01
Granted	279	66.11
Dividends	10	—
Forfeited or expired	(85)	66.62
Vested and issued (2)	(264)	56.43
Nonvested/unissued at December 31, 2022	460	$	64.34

(2)Includes shares for retiree payouts and those converted for taxes.

The weighted average grant date fair value of all restricted stock/units granted in 2021 and 2020 was $65.38 and $76.85, respectively.

As of December 31, 2022, total compensation cost related to all nonvested omnibus shares not yet recognized is $5.3 million, which is expected to be recognized over a weighted average period of 2.4 years.

Redeemable Noncontrolling Interests (Tables)

12 Months Ended

Dec. 31, 2022

Noncontrolling Interest [Abstract]

Summary of Redeemable Noncontrolling Interest

The following depicts changes to the balances of the redeemable noncontrolling interests:


	Linetec		Drum		Total
(Thousands of dollars)
Balance, December 31, 2020	$	165,716	$	—	$	165,716
Redeemable noncontrolling interest acquired	—		12,562		12,562
Net income attributable to redeemable noncontrolling interests	6,416		7		6,423
Redemption value adjustments	12,016		—		12,016
Balance, December 31, 2021	184,148		12,569		196,717

Net income attributable to redeemable noncontrolling interests	5,591		15		5,606
Redemption value adjustments	(3,325)		—		(3,325)
Redemption of equity interest from noncontrolling party	(39,649)		—		(39,649)
Balance, December 31, 2022	$	146,765	$	12,584	$	159,349

CONSOLIDATED BALANCE SHEETS - Southwest - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Regulated operations plant:
Gas plant	$ 9,453,907	$ 10,789,690
Less: accumulated depreciation	(2,674,157)	(3,397,736)
Construction work in progress	244,750	202,068
Net regulated operations plant	7,024,500	7,594,022
Other property and investments, net	1,281,172	1,316,479
Current assets:
Cash and cash equivalents	123,078	222,697
Accounts receivable, net of allowances	866,246	707,127
Accrued utility revenue	88,100	84,900
Income taxes receivable, net	8,738	16,816
Deferred purchased gas costs	450,120	291,145
Prepaid and other current assets	433,850	292,082
Total current assets	3,707,662	1,614,767
Noncurrent assets:
Goodwill	787,250	1,781,332
Deferred charges and other assets	395,948	458,536
Total noncurrent assets	1,183,280	2,239,989
Total assets	13,196,614	12,765,257
Capitalization:
Common stock	68,749	62,052
Additional paid-in capital	2,287,183	1,824,216
Accumulated other comprehensive loss, net	(44,242)	(46,761)
Retained earnings	747,069	1,114,313
Total Southwest Gas Holdings, Inc. equity	3,058,759	2,953,820
Long-term debt, less current maturities	4,403,299	4,115,684
Total capitalization	7,621,407	7,266,221
Commitments and contingencies (Note 10)
Current liabilities:
Current maturities of long-term debt	44,557	297,324
Short-term debt	1,542,806	1,909,000
Accounts payable	662,090	353,365
Customer deposits	51,182	59,327
Accrued general taxes	67,094	53,473
Accrued interest	38,556	30,964
Other current liabilities	369,743	396,126
Total current liabilities	3,422,963	3,112,049
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	682,067	768,868
Accumulated removal costs	445,000	480,583
Other deferred credits and other long-term liabilities	1,025,177	1,137,536
Total deferred income taxes and other credits	2,152,244	2,386,987
Total capitalization and liabilities	13,196,614	12,765,257
Southwest Gas Corporation
Regulated operations plant:
Gas plant	9,453,907	8,901,575
Less: accumulated depreciation	(2,674,157)	(2,538,508)
Construction work in progress	244,750	183,485
Net regulated operations plant	7,024,500	6,546,552
Other property and investments, net	169,397	153,093
Current assets:
Cash and cash equivalents	51,823	38,691
Accounts receivable, net of allowances	234,081	169,666
Accrued utility revenue	88,100	84,900
Income taxes receivable, net	103	7,826
Deferred purchased gas costs	450,120	291,145
Receivable from parent	2,130	1,031
Prepaid and other current assets	401,789	242,243
Total current assets	1,228,146	835,502
Noncurrent assets:
Goodwill	11,155	10,095
Deferred charges and other assets	370,483	405,021
Total noncurrent assets	381,638	415,116
Total assets	8,803,681	7,950,263
Capitalization:
Common stock	49,112	49,112
Additional paid-in capital	1,622,969	1,618,911
Accumulated other comprehensive loss, net	(38,261)	(46,913)
Retained earnings	935,355	906,827
Total Southwest Gas Holdings, Inc. equity	2,569,175	2,527,937
Long-term debt, less current maturities	3,251,296	2,440,603
Total capitalization	5,820,471	4,968,540
Commitments and contingencies (Note 10)
Current liabilities:
Current maturities of long-term debt	0	275,000
Short-term debt	225,000	250,000
Accounts payable	497,046	234,070
Customer deposits	51,182	56,127
Accrued general taxes	67,094	53,064
Accrued interest	29,569	22,926
Other current liabilities	150,817	146,422
Total current liabilities	1,020,708	1,037,609
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	683,948	638,828
Accumulated removal costs	445,000	424,000
Other deferred credits and other long-term liabilities	833,554	881,286
Total deferred income taxes and other credits	1,962,502	1,944,114
Total capitalization and liabilities	$ 8,803,681	$ 7,950,263

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Earnings Per Share, Basic and Diluted (Details) - shares shares in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Weighted average basic shares (in shares)	65,558	59,145	55,998
Effect of dilutive securities:
Restricted stock units (in shares)	0	114	78
Weighted average diluted shares (in shares)	65,558	59,259	56,076
Number of performance share units granted (in shares)	144	104	69
Restricted Stock Units (RSUs)
Effect of dilutive securities:
Antidilutive securities (in shares)	157

Cover - USD ($)

12 Months Ended

Dec. 31, 2022

Feb. 15, 2023

Jun. 30, 2022

Entity Information [Line Items]

Document Type

10-K

Document Annual Report

true

Document Period End Date

Dec. 31, 2022

Current Fiscal Year End Date

--12-31

Document Transition Report

false

Entity File Number

001-37976

Entity Registrant Name

Southwest Gas Holdings, Inc.

Entity Incorporation, State or Country Code

Entity Tax Identification Number

81-3881866

Entity Address, Address Line One

8360 S. Durango Dr.

Entity Address, Address Line Two

Post Office Box 98510

Entity Address, City or Town

Las Vegas,

Entity Address, State or Province

Entity Address, Postal Zip Code

89193-8510

City Area Code

(702)

Local Phone Number

876-7237

Title of 12(b) Security

Southwest Gas Holdings, Inc. Common Stock, $1 par value

Trading Symbol

SWX

Security Exchange Name

NYSE

Entity Well-known Seasoned Issuer

Yes

Entity Voluntary Filers

Entity Current Reporting Status

Yes

Entity Interactive Data Current

Yes

Entity Filer Category

Large Accelerated Filer

Entity Small Business

false

Entity Emerging Growth Company

false

ICFR Auditor Attestation Flag

true

Entity Shell Company

false

Entity Public Float

$ 5,834,690,207

Entity Common Stock, Shares Outstanding

67,146,347

Documents Incorporated by Reference


Description						Part Into Which Incorporated
Annual Report to Stockholders for the Year Ended December 31, 2022 2023 Proxy Statement						Parts I, II, and IV Part III

Entity Central Index Key

0001692115

Document Fiscal Year Focus

2022

Document Fiscal Period Focus

Amendment Flag

false

Southwest Gas Corporation

Entity Information [Line Items]

Document Type

10-K

Document Annual Report

true

Document Period End Date

Dec. 31, 2022

Current Fiscal Year End Date

--12-31

Document Transition Report

false

Entity File Number

1-7850

Entity Registrant Name

Southwest Gas Corporation

Entity Incorporation, State or Country Code

Entity Tax Identification Number

88-0085720

Entity Address, Address Line One

8360 S. Durango Dr.

Entity Address, Address Line Two

Post Office Box 98510

Entity Address, City or Town

Las Vegas,

Entity Address, State or Province

Entity Address, Postal Zip Code

89193-8510

City Area Code

(702)

Local Phone Number

876-7237

Entity Well-known Seasoned Issuer

Entity Voluntary Filers

Entity Current Reporting Status

Yes

Entity Interactive Data Current

Yes

Entity Filer Category

Non-accelerated Filer

Entity Small Business

false

Entity Emerging Growth Company

false

ICFR Auditor Attestation Flag

false

Entity Shell Company

false

Entity Central Index Key

0000092416

Document Fiscal Year Focus

2022

Document Fiscal Period Focus

Amendment Flag

false

Regulated Operations Plant and Leases - Supplemental Cash Flow Information Related to Leases (Details) - Centuri - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$ 16,725	$ 14,669	$ 12,889
Operating cash flows from finance leases	1,520	278	36
Financing cash flows from finance leases	11,985	3,547	199
ROU assets obtained in exchange for lease obligations:
Operating leases	22,653	11,597	19,372
Finance leases	$ 28,861	$ 3,332	$ 361

Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of year	$ 2,629	$ 1,928
Gross increases – tax positions in prior period	389	442
Gross increases – current period tax positions	54	259
Gross decreases – current period tax positions	0	0
Settlements	0	0
Lapse in statute of limitations	0	0
Unrecognized tax benefits at end of year	3,072	2,629
Southwest Gas Corporation
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Unrecognized tax benefits at beginning of year	2,362	1,793
Gross increases – tax positions in prior period	259	310
Gross decreases – tax positions in prior period	0	0
Gross increases – current period tax positions	23	259
Gross decreases – current period tax positions	0	0
Settlements	0	0
Lapse in statute of limitations	0	0
Unrecognized tax benefits at end of year	$ 2,644	$ 2,362

CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Operating revenues:
Regulated operations revenues	$ 2,199,682	$ 1,521,790	$ 1,350,585
Utility infrastructure services revenues	2,760,327	2,158,661	1,948,288
Total operating revenues	4,960,009	3,680,451	3,298,873
Operating expenses:
Net cost of gas sold	799,060	430,907	342,837
Operations and maintenance	636,766	473,146	408,116
Depreciation and amortization	470,455	371,041	332,027
Taxes other than income taxes	93,383	80,343	63,460
Utility infrastructure services expenses	2,529,318	1,955,467	1,729,429
Goodwill impairment and cost to sell	455,425	0	0
Total operating expenses	4,984,407	3,310,904	2,875,869
Operating income (loss)	(24,398)	369,547	423,004
Other income and (expenses):
Net interest deductions	(242,750)	(119,198)	(111,477)
Other income (deductions)	(6,189)	(3,499)	(6,789)
Total other income and (expenses)	(248,939)	(122,697)	(118,266)
Income (loss) before income taxes	(273,337)	246,850	304,738
Income tax expense (benefit)	(75,653)	39,648	65,753
Net income (loss)	(197,684)	207,202	238,985
Net income attributable to noncontrolling interests	5,606	6,423	6,661
Net income (loss) attributable to Southwest Gas Holdings, Inc.	$ (203,290)	$ 200,779	$ 232,324
Earnings (loss) per share:
Basic earnings per common share (in USD per share)	$ (3.10)	$ 3.39	$ 4.15
Diluted earnings per common share (in USD per share)	$ (3.10)	$ 3.39	$ 4.14
Weighted average shares:
Basic (in shares)	65,558	59,145	55,998
Diluted (in shares)	65,558	59,259	56,076

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Other Property and Investments (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Property, Plant and Equipment [Line Items]
Other property	$ 31,075	$ 59,337
Other property and investments	1,281,172	1,316,479
Non-regulated property, equipment, and intangibles	1,677,218	1,616,392
Non-regulated accumulated provision for depreciation and amortization	(596,518)	(512,343)
Southwest Gas Corporation
Property, Plant and Equipment [Line Items]
Net cash surrender value of COLI policies	136,245	149,947
Other property	33,152	3,146
Other property and investments	$ 169,397	$ 153,093

Pension and Other Postretirement Benefits

12 Months Ended

Dec. 31, 2022

Retirement Benefits [Abstract]

Pension and Other Postretirement Benefits

Note 11 - Pension and Other Postretirement Benefits

Southwest Gas Corporation

Employees’ Investment Plan

An Employees’ Investment Plan (“EIP”) is offered to eligible employees of Southwest through deduction of a percentage of base compensation, subject to Internal Revenue Service (“IRS”) limitations. The EIP provides for purchases of various mutual fund investments and Company common stock. For employees hired on or before December 31, 2021, one-half of amounts deferred are matched, up to a maximum matching contribution of 3.5% of an employee’s annual compensation. Employees hired on or after January 1, 2022 are eligible for non-elective employer contributions of 3% plus a matching contribution (dollar-for-dollar) up to 7% of eligible compensation. Officers hired after January 1, 2022 are eligible for non-elective and matching contributions. Contributions to the plan by Southwest were $6.9 million, $6.1 million, and $5.9 million for 2022, 2021, and 2020, respectively.

Deferred Compensation Plan

A deferred compensation plan is offered to all officers of Southwest and a separate deferred compensation plan is offered to members of the Company’s Board of Directors. The plans provide the opportunity to defer up to 100% of annual cash compensation. One-half of amounts deferred by officers are matched, up to a maximum matching contribution of 3.5% of an officer’s annual base salary. Upon retirement, payments of compensation deferred, plus interest, are made in equal monthly installments over 10, 15, or 20 years, as elected by the participant. Directors have an additional option to receive such payments over a five-year period. Deferred compensation earns interest at a rate determined each January. The interest rate equals 150% of Moody’s Seasoned Corporate Bond Rate Index.

Pension and Postretirement Plans

A noncontributory qualified retirement plan with defined benefits covering substantially all Southwest employees hired on or before December 31, 2021 is available, in addition to a separate unfunded supplemental executive retirement plan (“SERP”), which is limited to Southwest’s officers. Postretirement benefits other than pensions (“PBOP”) are provided to qualified retirees for health care, dental, vision and life insurance benefits. The defined benefit qualified retirement plan, SERP, and PBOP are

not available to Southwest employees hired on or after January 1, 2022. As noted above, employees hired on or after that date, are eligible for enhanced contributions to the EIP.

The overfunded or underfunded positions of defined benefit postretirement plans, including pension plans, are recognized in the Consolidated Balance Sheets. Any actuarial gains and losses, prior service costs, and transition assets or obligations are recognized in Accumulated other comprehensive income under Stockholders’ equity, net of tax, until they are amortized as a component of net periodic benefit cost.

A regulatory asset has been established for the portion of the total amounts otherwise chargeable to Accumulated other comprehensive income that are expected to be recovered through rates in future periods. Changes in actuarial gains and losses and prior service costs pertaining to the regulatory asset will be recognized as an adjustment to the regulatory asset account as these amounts are amortized and recognized as components of net periodic pension costs each year.

The qualified retirement plan invests the majority of its plan assets in common collective trusts, which include a well-diversified portfolio of domestic and international equity securities and fixed income securities, and are managed by a professional investment manager appointed by Southwest. The investment manager has full discretionary authority to direct the investment of plan assets held in trust within the specific guidelines prescribed by Southwest through the plan’s investment policy statement. In 2016, Southwest adopted a liability driven investment (“LDI”) strategy for part of the portfolio, a form of investing designed to better match the movement in pension plan assets with the impact of interest rate changes and inflation assumption changes on the pension plan liability. The implementation of the LDI strategy will be phased in over time by using a glide path. The glide path is designed to increase the allocation of the plan’s assets to fixed income securities, as the funded status of the plan increases, in order to more closely match the duration of the plan assets to that of the plan liability. Pension plan assets are held in a Master Trust. The pension plan funding policy is in compliance with the federal government’s funding requirements.

Pension costs for these plans are affected by the amount and timing of cash contributions to the plans, the return on plan assets, discount rates, and by employee demographics, including age, compensation, and length of service. Changes made to the provisions of the plans may also impact current and future pension costs. Actuarial formulas are used in the determination of pension costs and are affected by actual plan experience and assumptions about future experience. Key actuarial assumptions include the expected return on plan assets, the discount rate used in determining the projected benefit obligation and pension costs, and the assumed rate of increase in employee compensation. Relatively small changes in these assumptions, particularly the discount rate, may significantly affect pension costs and plan obligations for the qualified retirement plan. In determining the discount rate, management matches the plan’s projected cash flows to a spot-rate yield curve based on highly rated corporate bonds. Changes to the discount rate from year-to-year, if any, are generally made in increments of 25 basis points.

There was a 225 basis point increase in the discount rate between years, as reflected below. The methodology utilized to determine the discount rate was consistent with prior years. The weighted-average rate of compensation increase remained the same (consistent with management’s expectations overall). The asset return assumption (which impacts the following year’s expense) increased by 25 basis points. The rates are presented in the table below:


	December 31,
	2022		2021
Discount rate	5.25	%	3.00	%
Weighted-average rate of compensation increase	3.25	%	3.25	%
Asset return assumption	6.75	%	6.50	%

Future years’ expense level movements (up or down) will continue to be greatly influenced by long-term interest rates, asset returns, and funding levels.

The following table sets forth the retirement plan, SERP, and PBOP funded statuses and amounts recognized on the Consolidated Balance Sheets and Consolidated Statements of Income.


	Year Ended December 31,
	2022									2021
(Thousands of dollars)	Qualified Retirement Plan			SERP			PBOP			Qualified Retirement Plan			SERP			PBOP
Change in benefit obligations:
Benefit obligation for service rendered to date at beginning of year (PBO/PBO/APBO)	$	1,531,197		$	49,530		$	84,226		$	1,499,239		$	53,631		$	82,205
Service cost	44,110			424			1,941			41,159			526			1,691
Interest cost	45,006			1,441			2,452			40,432			1,431			2,193

Actuarial loss (gain)	(399,066)			(6,134)			(18,260)			8,908			(3,244)			3,438
Benefits paid	(61,796)			(3,164)			(4,922)			(58,541)			(2,814)			(5,301)
Benefit obligation at end of year (PBO/PBO/APBO)	1,159,451			42,097			65,437			1,531,197			49,530			84,226
Change in plan assets:
Market value of plan assets at beginning of year	1,366,043			—			52,168			1,186,433			—			52,286
Actual return on plan assets	(330,203)			—			(6,036)			136,151			—			7,717
Employer contributions	56,000			3,164			—			102,000			2,814			—
Benefits paid	(61,796)			(3,164)			(7,673)			(58,541)			(2,814)			(7,835)
Market value of plan assets at end of year	1,030,044			—			38,459			1,366,043			—			52,168
Funded status at year end	$	(129,407)		$	(42,097)		$	(26,978)		$	(165,154)		$	(49,530)		$	(32,058)
Weighted-average assumptions (benefit obligation):
Discount rate	5.25		%	5.25		%	5.25		%	3.00		%	3.00		%	3.00		%
Weighted-average rate of compensation increase	3.25		%	3.25		%	N/A			3.25		%	3.25		%	N/A

Estimated funding for the plans above during calendar year 2023 is expected to be approximately $59 million, of which $56 million pertains to the retirement plan. Management monitors plan assets and liabilities and may, at its discretion, increase plan funding levels above the minimum in order to achieve a desired funded status and avoid or minimize potential benefit restrictions.

The accumulated benefit obligation for the retirement plan and the SERP is presented below:


	December 31,
(Thousands of dollars)	2022		2021
Retirement plan	$	1,074,493	$	1,395,773
SERP	39,263		46,885

Benefits expected to be paid for pension, SERP, and PBOP over the next 10 years are as follows:


(Millions of dollars)	2023		2024		2025		2026		2027		2028-2032
Pension	$	65.0	$	67.0	$	68.0	$	69.0	$	71.0	$	377.0
SERP	3.3		3.3		3.2		3.1		3.1		14.6
PBOP	5.1		5.2		5.2		5.1		5.2		25.6

No assurance can be made that actual funding and benefits paid will match these estimates.

For PBOP measurement purposes, the per capita cost of the covered health care benefits medical rate trend assumption is 6.0%, declining to 4.5%. Specific contributions are made for health care benefits of employees who retire after 1988, but Southwest pays all covered health care costs for employees who retired prior to 1989. The medical trend rate assumption noted above applies to the benefit obligations of pre-1989 retirees only.

The service cost component of net periodic benefit costs included in the table below is part of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of that portion of overall net periodic benefit costs to the same accounts to which productive labor is charged. As a result, service costs become components of various accounts, primarily Operations and maintenance expense, Net regulated operations plant, and Deferred charges and other assets for both the Company and Southwest. The non-service cost components of net periodic benefit cost are reflected in Other income (deductions) on the Consolidated Statements of Income of each entity, based on accounting guidance for the presentation of such costs.

Components of net periodic benefit cost:


	Qualified Retirement Plan						SERP						PBOP
(Thousands of dollars)	2022		2021		2020		2022		2021		2020		2022		2021		2020
Service cost	$44,110		$41,159		$34,299		$424		$526		$389		$1,941		$1,691		$1,581
Interest cost	45,006		40,432		45,555		1,441		1,431		1,604		2,452		2,193		2,582
Expected return on plan assets	(79,913)		(72,352)		(65,296)		—		—		—		(3,228)		(3,239)		(3,408)
Amortization of prior service cost	—		—		—		—		—		—		175		959		1,155
Amortization of net actuarial loss	32,468		41,955		36,025		2,350		2,642		1,805		—		—		—
Net periodic benefit cost	$41,671		$51,194		$50,583		$4,215		$4,599		$3,798		$1,340		$1,604		$1,910
Weighted-average assumptions (net benefit cost)
Discount rate	3.00	%	2.75	%	3.50	%	3.00	%	2.75	%	3.50	%	3.00	%	2.75	%	3.50	%
Expected return on plan assets	6.50	%	6.50	%	6.75	%	N/A		N/A		N/A		6.50	%	6.50	%	6.75	%
Weighted-average rate of compensation increase	3.25	%	3.00	%	3.25	%	3.25	%	3.00	%	3.25	%	N/A		N/A		N/A

Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income


	Year Ended December 31,
	2022								2021								2020
(Thousands of dollars)	Total		Qualified Retirement Plan		SERP		PBOP		Total		Qualified Retirement Plan		SERP		PBOP		Total		Qualified Retirement Plan		SERP		PBOP
Net actuarial loss (gain) (a)	$	(4,079)	$	11,049	$	(6,133)	$	(8,995)	$	(59,176)	$	(54,892)	$	(3,245)	$	(1,039)	$	57,539	$	45,665	$	7,240	$	4,634
Amortization of prior service cost (b)	(175)		—		—		(175)		(959)		—		—		(959)		(1,155)		—		—		(1,155)
Amortization of net actuarial loss (b)	(34,818)		(32,468)		(2,350)		—		(44,597)		(41,955)		(2,642)		—		(37,830)		(36,025)		(1,805)		—
Prior service cost	—		—		—		—		—		—		—		—		—		—		—		—
Regulatory adjustment	28,232		19,062		—		9,170		88,194		86,196		—		1,998		(7,435)		(3,956)		—		(3,479)
Recognized in other comprehensive (income) loss	(10,840)		(2,357)		(8,483)		—		(16,538)		(10,651)		(5,887)		—		11,119		5,684		5,435		—
Net periodic benefit costs recognized in net income	47,226		41,671		4,215		1,340		57,397		51,194		4,599		1,604		56,291		50,583		3,798		1,910
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	$	36,386	$	39,314	$	(4,268)	$	1,340	$	40,859	$	40,543	$	(1,288)	$	1,604	$	67,410	$	56,267	$	9,233	$	1,910

The table above discloses the net gain or loss and prior service cost recognized in Other comprehensive income, separated into (a) amounts initially recognized in Other comprehensive income, and (b) amounts subsequently recognized as adjustments to Other comprehensive income as those amounts are amortized as components of net periodic benefit cost. See also Note 6 - Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI").


	December 31,
	2022						2021
(Thousands of dollars)	Qualified Retirement Plan		PBOP		Total		Qualified Retirement Plan		PBOP		Total
Assets at fair value:
Level 1 – Quoted prices in active markets for identical financial assets
Mutual funds	$	—	$	31,631	$	31,631	$	—	$	35,194	$	35,194
Total Level 1 Assets (1)	—		31,631		31,631		—		35,194		35,194
Level 2 – Significant other observable inputs
Commingled trust equity funds (2)
Global	266,368		1,673		268,041		373,936		4,538		378,474
International	117,976		741		118,717		158,461		1,923		160,384
U.S. equity securities	184,300		1,159		185,459		279,062		3,386		282,448
Emerging markets	62,436		392		62,828		82,004		995		82,999
Commingled trust fixed income funds (3)	390,070		2,450		392,520		463,942		5,630		469,572
Pooled funds and mutual funds	6,359		412		6,771		5,979		500		6,479
Government fixed income and mortgage backed securities	159		1		160		196		2		198
Total Level 2 assets (4)	1,027,668		6,828		1,034,496		1,363,580		16,974		1,380,554
Total Plan assets at fair value	1,027,668		38,459		1,066,127		1,363,580		52,168		1,415,748
Insurance company general account contracts (5)	2,376		—		2,376		2,463		—		2,463
Total Plan assets	$	1,030,044	$	38,459	$	1,068,503	$	1,366,043	$	52,168	$	1,418,211

▪Global equities, including domestic equities

▪International developed countries equities

▪Domestic equities

▪Emerging markets equities

of investments. The changes in the value of the fixed income funds are intended to offset the changes in the pension plan liabilities due to changes in the discount rate.

Centuri

Defined Contribution Plans

Centuri offers defined contribution plans under Section 401(k) of the Internal Revenue Code to its eligible employees, regardless of whether they are covered under collective-bargaining agreements. Eligibility requirements vary, as does timing of participation, matching, vesting, and profit-sharing features of the plans. Contributions by Centuri to these plans for the years ended December 31, 2022, 2021, and 2020 were $13 million, $9 million, and $9 million, respectively.

Deferred Compensation Plan

Centuri sponsors a nonqualified deferred compensation plan that is offered to a select group of management and highly-compensated employees. The plan allows participants to defer up to 80% of base salary and provides a match of 100% of contributions up to 5% of a participant’s salary. The plan also allows Centuri, at its election, to credit participant accounts with discretionary contributions. Participants are 100% vested in salary deferrals, contributions, and all earnings. Participant accounts include a return based on the performance of the underlying investment options selected. Payments from the plan are designated at each annual enrollment period based on specified triggering events and are payable by lump sum or on an annual installment basis.

Multiemployer Pension Plans

Centuri makes defined contributions to several multiemployer defined benefit pension plans under the terms of collective bargaining agreements (“CBAs”) with various unions representing certain employees. Contribution rates are generally specified in the CBAs and are made to the plans on a “pay-as-you-go” basis. Such contributions correspond to the number of union employees and the particular plans in which they participate, and vary depending upon the location, number of ongoing projects, and the need for union resources in connection with those projects.

The risks of participating in multiemployer plans are different from single-employer plans, including: (i) assets contributed to the multiemployer plan by one employer may be used to provide benefits to employees of other participating employers; (ii) if a participating employer stops contributing to the multiemployer plan, the unfunded obligations of the plan may become the obligation of the remaining participating employers; and (iii) if a participating employer chooses to stop participating in these multiemployer plans, the employer may be required to pay those plans an amount based on the underfunded status of the plan.

The Pension Protection Act of 2006 requires special funding and operational rules for multiemployer plans in the U.S., including classification of the plans (based on multiple factors, including the funded status of the plan), the most severe of which is “critical.” Depending upon the classification, plans may be required to adopt measures to improve their funded status through a funding improvement or rehabilitation plan, which may require additional contributions from employers (in the form of a surcharge on benefit contributions) and/or modification of retiree benefits. The amount of additional funds, if any, that Centuri may be obligated to contribute to these plans in the future cannot be estimated due to the uncertainty regarding future levels of work that may require the utilization of union employees covered by these plans, as well as uncertainty as to the future contribution levels and possible surcharges on contributions that may apply to these plans at that time.

Centuri contributed $71 million, $57.4 million, and $44.3 million collectively to the plans for the years ended December 31, 2022, 2021, and 2020, respectively. Substantially all of the contributions made by Centuri during these years were to U.S. plans that were not classified as critical, and for which no special surcharges were assessed. Eight plans were classified as critical and required special surcharges; the aggregate contributions to these plans were $3.8 million for the year ended December 31, 2022 and were insignificant during the periods ending December 31, 2021 and 2020.

- Definition

The entire disclosure for retirement benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 55
-Paragraph 17
-URI https://asc.fasb.org/extlink&oid=123450688&loc=d3e4179-114921

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section S99
-Paragraph 2
-URI https://asc.fasb.org/extlink&oid=21916913&loc=d3e273930-122802

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 715
-SubTopic 20
-Section 50
-Paragraph 1
-Subparagraph (d)(i)
-URI https://asc.fasb.org/extlink&oid=123447040&loc=d3e1928-114920

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
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Reference 5: http://www.xbrl.org/2003/role/disclosureRef
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Reference 7: http://www.xbrl.org/2003/role/disclosureRef
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Reference 8: http://www.xbrl.org/2003/role/disclosureRef
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+ Details

Regulated Operations Plant and Leases - Components of Lease Expense (Details) - Centuri - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Lessee, Lease, Description [Line Items]
Operating lease cost	$ 17,881	$ 15,279	$ 14,294
Amortization of ROU assets	7,702	2,138	140
Interest on lease liabilities	1,520	278	37
Total finance lease cost	9,222	2,416	177
Short-term lease cost	120,339	103,800	19,806
Total lease cost	$ 147,442	$ 121,495	$ 34,277

Regulatory Assets and Liabilities - Schedule of Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	$ 1,088,178	$ 831,610
Net regulatory assets (liabilities)	$ 195,372	(212,018)
Accrued pension and other postretirement benefit costs, recovery period	5 years
Regulatory assets, accrued absence time, lag period	1 year
Regulatory assets, margin, interest and property tax-tracking, recovery period	24 months
Other current liabilities
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	$ 30,300
Unsecured Debt \| MountainWest unsecured senior notes, 4.875%, due in 2041
Regulatory Assets And Liabilities [Line Items]
Debt instrument face amount		$ 180,000
Debt instrument, stated interest rate		4.875%
Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		$ 798,897
Net regulatory assets (liabilities)		(95,640)
Deferred purchased gas costs
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	0	5,736
Deferred purchased gas costs \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		0
Accumulated removal costs
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	445,000	482,558
Accumulated removal costs \| Other current liabilities
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		2,000
Accumulated removal costs \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		424,000
Unamortized gain on reacquired debt
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	6,572	7,108
Unamortized gain on reacquired debt \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		7,108
Regulatory excess deferred/other taxes and gross-up
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	424,921	511,567
Regulatory excess deferred/other taxes and gross-up \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		446,333
Margin, interest - and property tax-tracking
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	10,920	8,523
Margin, interest - and property tax-tracking \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		8,523
Unrecognized other postretirement benefit cost
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	0	17,815
Unrecognized other postretirement benefit cost \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		0
Other
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	5,393	10,321
Other \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities		8,573
Gross-up related to contributions in aid of construction
Regulatory Assets And Liabilities [Line Items]
Regulatory liabilities	2,700
Accrued pension and other postretirement benefit costs
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	311,124	339,356
Accrued pension and other postretirement benefit costs \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		339,356
Deferred purchased gas costs
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	450,120	291,145
Deferred purchased gas costs \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		291,145
Settled interest rate hedges
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	0	31,278
Settled interest rate hedges \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		0
Accrued purchased gas costs
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	207,368	51,631
Accrued purchased gas costs \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		51,631
Unamortized premium on reacquired debt
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	14,707	16,283
Unamortized premium on reacquired debt \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		16,283
Accrued absence time
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	17,854	16,975
Accrued absence time \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		16,975
Margin, interest - and property tax-tracking
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	21,024	22,709
Margin, interest - and property tax-tracking \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		22,709
Other
Regulatory Assets And Liabilities [Line Items]
Regulatory assets	$ 65,981	62,233
Other \| Southwest Gas Corporation
Regulatory Assets And Liabilities [Line Items]
Regulatory assets		$ 60,798

Income Taxes - Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate (Details)	12 Months Ended			36 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Income Taxes [Line Items]
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
Net state taxes	3.20%	1.00%	3.00%
Tax credits	0.20%	(0.50%)	(0.50%)
Company-owned life insurance	(0.80%)	(1.10%)	(0.80%)
Amortization of excess deferred taxes	5.20%	(4.30%)	(0.80%)
All other differences	(1.10%)	0.00%	(0.30%)
Consolidated effective income tax rate	27.70%	16.10%	21.60%	24.00%
Southwest Gas Corporation
Income Taxes [Line Items]
U.S. federal statutory income tax rate	21.00%	21.00%	21.00%
Net state taxes	1.60%	0.30%	1.70%
Tax credits	(0.30%)	(0.60%)	(0.70%)
Company-owned life insurance	0.60%	(0.90%)	(1.00%)
Amortization of excess deferred taxes	(6.90%)	(4.90%)	(1.30%)
All other differences	0.50%	(1.30%)	(1.40%)
Consolidated effective income tax rate	16.50%	13.60%	18.30%	24.00%

Revenue - Narrative (Details) $ in Millions	12 Months Ended
Revenue - Narrative (Details) $ in Millions	Dec. 31, 2022 USD ($) type customer contract
Segment Reporting Information [Line Items]
Number of customers party to contracts with rate components subject to negotiation (less than) \| customer	24
Change in contract liability, revenue recognized \| $	$ 11.9
Southwest Gas Corporation
Segment Reporting Information [Line Items]
Number of types of services provided to customers	2
Number of customers \| customer	2,200,000
Centuri
Segment Reporting Information [Line Items]
Number of types of services provided to customers	3
Number of types of agreements with customers	2
Number of contracts with original duration more than one year \| contract	57
Centuri \| Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2023-01-01
Segment Reporting Information [Line Items]
Transaction price allocated to unsatisfied performance obligations of contracts \| $	$ 440.8
Transaction price allocated to unsatisfied performance obligations of contracts, period	2 years

Pension and Other Postretirement Benefits - Schedule of Net Periodic Benefit Cost and Weighted-Average Assumptions (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Defined Benefit Plan Disclosure [Line Items]
Net periodic benefit cost	$ 47,226	$ 57,397	$ 56,291
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	44,110	41,159	34,299
Interest cost	45,006	40,432	45,555
Expected return on plan assets	(79,913)	(72,352)	(65,296)
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	32,468	41,955	36,025
Net periodic benefit cost	$ 41,671	$ 51,194	$ 50,583
Weighted-average assumptions (net benefit cost)
Discount rate	3.00%	2.75%	3.50%
Expected return on plan assets	6.50%	6.50%	6.75%
Weighted-average rate of compensation increase	3.25%	3.00%	3.25%
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 424	$ 526	$ 389
Interest cost	1,441	1,431	1,604
Expected return on plan assets	0	0	0
Amortization of prior service cost	0	0	0
Amortization of net actuarial loss	2,350	2,642	1,805
Net periodic benefit cost	$ 4,215	$ 4,599	$ 3,798
Weighted-average assumptions (net benefit cost)
Discount rate	3.00%	2.75%	3.50%
Weighted-average rate of compensation increase	3.25%	3.00%	3.25%
PBOP
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 1,941	$ 1,691	$ 1,581
Interest cost	2,452	2,193	2,582
Expected return on plan assets	(3,228)	(3,239)	(3,408)
Amortization of prior service cost	175	959	1,155
Amortization of net actuarial loss	0	0	0
Net periodic benefit cost	$ 1,340	$ 1,604	$ 1,910
Weighted-average assumptions (net benefit cost)
Discount rate	3.00%	2.75%	3.50%
Expected return on plan assets	6.50%	6.50%	6.75%

Debt - Estimated Maturities of Long-Term Debt (Details) $ in Thousands	Dec. 31, 2022 USD ($)
Debt Instrument [Line Items]
2023	$ 44,558
2024	42,552
2025	91,004
2026	197,056
2027	351,242
Total	726,412
Secured Debt \| Centuri secured revolving credit facility
Debt Instrument [Line Items]
2023	0
2024	0
2025	0
2026	81,955
2027	0
Total	81,955
Secured Debt \| Centuri secured term loan facility
Debt Instrument [Line Items]
2023	14,313
2024	11,450
2025	11,450
2026	11,450
2027	11,450
Total	60,113
Other debt obligations
Debt Instrument [Line Items]
2023	30,245
2024	31,102
2025	29,554
2026	28,651
2027	7,292
Total	126,844
Southwest Gas Corporation
Debt Instrument [Line Items]
2023	0
2024	0
2025	50,000
2026	75,000
2027	332,500
Total	457,500
Southwest Gas Corporation \| Debentures
Debt Instrument [Line Items]
2023	0
2024	0
2025	0
2026	75,000
2027	332,500
Total	407,500
Southwest Gas Corporation \| Revolving credit facility and commercial paper
Debt Instrument [Line Items]
2023	0
2024	0
2025	50,000
2026	0
2027	0
Total	$ 50,000

Revenue - Summary of Information about Receivables (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Revenue from Contract with Customer [Abstract]
Contracts receivable, net	$ 394,022	$ 296,005
Revenue earned on contracts in progress in excess of billings	238,059	214,774
Amounts billed in excess of revenue earned on contracts	$ 35,769	$ 11,860

Regulated Operations Plant and Leases - Schedule of Maturities of Lease Liabilities (Details) - Centuri - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Operating Leases
2023	$ 17,392
2024	15,267
2025	12,595
2026	10,646
2027	10,146
Thereafter	43,078
Total lease payments	109,124
Less imputed interest	18,142
Operating lease liabilities	90,982	$ 85,115
Finance Leases
2023	13,657
2024	12,225
2025	9,852
2026	7,263
2027	5,311
Thereafter	2,374
Total lease payments	50,682
Less imputed interest	4,416
Finance lease liabilities	$ 46,266	$ 29,443

Background, Organization, and Summary of Significant Accounting Policies - Narrative (Details)	3 Months Ended	12 Months Ended
	Dec. 31, 2022 USD ($) director	Dec. 31, 2022 USD ($) director	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	May 09, 2022	Oct. 10, 2021
Significant Accounting Policies [Line Items]
Disposal Group, Not Discontinued Operation, Gain (Loss) on Disposal, Statement of Income or Comprehensive Income [Extensible Enumeration]		Goodwill impairment and cost to sell
Number of new board of directors appointed \| director	3	3
Rights agreement amendment, beneficial ownership percentage					24.90%	10.00%
Amortization expenses		$ 29,800,000	$ 17,300,000	$ 10,800,000
Capital expenditures incurred but not yet paid, increase (decrease)		23,400,000	15,500,000
Cumulative foreign earnings	$ 79,000,000	$ 79,000,000
Deferred purchased gas costs, recovered or refunded period		1 year
Accrued purchased gas costs	207,000,000	$ 207,000,000	52,000,000
Dividends declared but not yet paid	$ 41,600,000	41,600,000	36,000,000
Debt portion		3,535,000	1,046,000	3,202,000
Equity AFUDC		$ 0	0	4,724,000
Icahn Group
Significant Accounting Policies [Line Items]
Number of director designated by counterparty \| director	4	4
Money Market Funds
Significant Accounting Policies [Line Items]
Money market fund investments	$ 30,000,000	$ 30,000,000	20,000,000
Customer relationships
Significant Accounting Policies [Line Items]
Weighted-average amortization period		19 years
Trade names and trademarks
Significant Accounting Policies [Line Items]
Weighted-average amortization period		15 years
Customer contracts backlog
Significant Accounting Policies [Line Items]
Weighted-average amortization period		1 year
Minimum
Significant Accounting Policies [Line Items]
Number of strategic transactions committee directors \| director	3	3
Number of new board of directors appointed \| director	2	2
Maximum
Significant Accounting Policies [Line Items]
Number of strategic transactions committee directors \| director	6	6
MountainWest
Significant Accounting Policies [Line Items]
Debt portion		$ 86,000
Equity AFUDC		$ 465,000
MountainWest \| White River Hub, LLC
Significant Accounting Policies [Line Items]
VIE ownership percentage		50.00%
Maximum loss exposure amount	$ 25,000,000	$ 25,000,000
Centuri \| W.S. Nicholls Western Construction LTD
Significant Accounting Policies [Line Items]
VIE ownership percentage		50.00%
Maximum loss exposure amount	11,400,000	$ 11,400,000
Southwest Gas Corporation
Significant Accounting Policies [Line Items]
Goodwill impairment loss		0	0
Capital expenditures incurred but not yet paid, increase (decrease)		19,700,000	13,900,000
Accrued purchased gas costs	207,000,000	207,000,000	52,000,000
Gas pipe materials and operating supplies	77,300,000	77,300,000	62,900,000
Reclassification associated with assets held for sale	27,000,000
Impairment loss	2,900,000
Equity AFUDC		0	0	$ 4,724,000
Southwest Gas Corporation \| Money Market Funds
Significant Accounting Policies [Line Items]
Money market fund investments	$ 17,600,000	$ 17,600,000	$ 0
Discontinued Operations, Disposed of by Sale \| MountainWest
Significant Accounting Policies [Line Items]
Ownership percentage disposed	100.00%	100.00%
Discontinued operation, consideration	$ 1,500,000,000	$ 1,500,000,000
Disposal Group, Held-for-sale, Not Discontinued Operations \| MountainWest
Significant Accounting Policies [Line Items]
Ownership percentage disposed	100.00%	100.00%
Discontinued operation, consideration	$ 1,500,000,000	$ 1,500,000,000
Goodwill impairment loss		449,600,000
Disposal selling costs		$ 5,819,000

Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") (Tables)

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss):


	Year Ended December 31,
	2022						2021						2020
(Thousands of dollars)	Before- Tax Amount		Tax (Expense) or Benefit (1)		Net-of- Tax Amount		Before- Tax Amount		Tax (Expense) or Benefit (1)		Net-of- Tax Amount		Before- Tax Amount		Tax (Expense) or Benefit (1)		Net-of- Tax Amount
Defined benefit pension plans:
Net actuarial gain/(loss)	$	4,079	$	(980)	$	3,099	$	59,176	$	(14,202)	$	44,974	$	(57,539)	$	13,809	$	(43,730)
Amortization of prior service cost	175		(42)		133		959		(230)		729		1,155		(277)		878
Amortization of net actuarial (gain)/loss	34,818		(8,357)		26,461		44,597		(10,703)		33,894		37,830		(9,079)		28,751

Regulatory adjustment	(28,232)		6,775		(21,457)		(88,194)		21,167		(67,027)		7,435		(1,785)		5,650
Pension plans other comprehensive income (loss)	10,840		(2,604)		8,236		16,538		(3,968)		12,570		(11,119)		2,668		(8,451)
FSIRS (designated hedging activities):
Amounts reclassified into net income	545		(129)		416		2,174		(522)		1,652		3,247		(780)		2,467
FSIRS other comprehensive income (loss)	545		(129)		416		2,174		(522)		1,652		3,247		(780)		2,467
Total other comprehensive income (loss) –Southwest Gas Corporation	11,385		(2,733)		8,652		18,712		(4,490)		14,222		(7,872)		1,888		(5,984)
Foreign currency translation adjustments:
Translation adjustments	(6,133)		—		(6,133)		20		—		20		1,713		—		1,713
Foreign currency other comprehensive income (loss)	(6,133)		—		(6,133)		20		—		20		1,713		—		1,713
Total other comprehensive income (loss) – Southwest Gas Holdings, Inc.	$	5,252	$	(2,733)	$	2,519	$	18,732	$	(4,490)	$	14,242	$	(6,159)	$	1,888	$	(4,271)

(1) Tax amounts are calculated using a 24% rate. With regard to foreign currency translation adjustments, the Company has elected to indefinitely reinvest the earnings of Centuri’s Canadian subsidiaries in Canada, thus preventing deferred taxes on such earnings. As a result of this assertion, and no repatriation of earnings anticipated, the Company is not recognizing a tax effect or presenting a tax expense or benefit for currency translation adjustments in Other comprehensive income (loss).

Schedule of Rollforward of Accumulated Other Comprehensive Income

The following table represents a rollforward of AOCI, presented on the Company’s Consolidated Balance Sheets and its Consolidated Statements of Equity:


	Defined Benefit Plans						FSIRS						Foreign Currency Items
(Thousands of dollars)	Before-Tax		Tax (Expense) Benefit (4)		After-Tax		Before- Tax		Tax (Expense) Benefit (4)		After-Tax		Before- Tax		Tax (Expense) Benefit		After-Tax		AOCI
Beginning Balance AOCI December 31, 2021	$	(61,182)	$	14,685	$	(46,497)	$	(545)	$	129	$	(416)	$	152	$	—	$	152	$	(46,761)
Net actuarial gain/(loss)	4,079		(980)		3,099		—		—		—		—		—		—		3,099
Translation adjustments	—		—		—		—		—		—		(6,133)		—		(6,133)		(6,133)
Other comprehensive income before reclassifications	4,079		(980)		3,099		—		—		—		(6,133)		—		(6,133)		(3,034)
FSIRS amount reclassified from AOCI (1)	—		—		—		545		(129)		416		—		—		—		416
Amortization of prior service cost (2)	175		(42)		133		—		—		—		—		—		—		133
Amortization of net actuarial loss (2)	34,818		(8,357)		26,461		—		—		—		—		—		—		26,461

Regulatory adjustment (3)	(28,232)		6,775		(21,457)		—		—		—				—		—		(21,457)
Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	10,840		(2,604)		8,236		545		(129)		416		(6,133)		—		(6,133)		2,519
Ending Balance AOCI December 31, 2022	$	(50,342)	$	12,081	$	(38,261)	$	—	$	—	$	—	$	(5,981)	$	—	$	(5,981)	$	(44,242)

(1)The FSIRS reclassification amount is included in Net interest deductions on the Company’s Consolidated Statements of Income.

(2)These AOCI components are included in the computation of net periodic benefit cost (see Note 11 - Pension and Other Postretirement Benefits for additional details).

(3)The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included in Deferred charges and other assets on the Company’s Consolidated Balance Sheets).

(4) Tax amounts are calculated using a 24% rate.

The following table represents a rollforward of AOCI, presented on Southwest’s Consolidated Balance Sheets:


	Defined Benefit Plans						FSIRS
(Thousands of dollars)	Before-Tax		Tax (Expense) Benefit (9)		After- Tax		Before- Tax		Tax (Expense) Benefit (9)		After- Tax		AOCI
Beginning Balance AOCI December 31, 2021	$	(61,182)	$	14,685	$	(46,497)	$	(545)	$	129	$	(416)	$	(46,913)
Net actuarial gain/(loss)	4,079		(980)		3,099		—		—		—		3,099
Other comprehensive loss before reclassifications	4,079		(980)		3,099		—		—		—		3,099
FSIRS amount reclassified from AOCI (6)	—		—		—		545		(129)		416		416
Amortization of prior service cost (7)	175		(42)		133		—		—		—		133
Amortization of net actuarial loss (7)	34,818		(8,357)		26,461		—		—		—		26,461

Regulatory adjustment (8)	(28,232)		6,775		(21,457)		—		—		—		(21,457)
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation	10,840		(2,604)		8,236		545		(129)		416		8,652
Ending Balance AOCI December 31, 2022	$	(50,342)	$	12,081	$	(38,261)	$	—	$	—	$	—	$	(38,261)

(6) The FSIRS reclassification amount is included in Net interest deductions on Southwest’s Consolidated Statements of Income.

(7) These AOCI components are included in the computation of net periodic benefit cost (see Note 11 - Pension and Other Postretirement Benefits for additional details).

(8) The regulatory adjustment represents the portion of the activity above that is expected to be recovered through rates in the future (the related regulatory asset is included Deferred charges and other assets on Southwest’s Consolidated Balance Sheets).

(9) Tax amounts are calculated using a 24% rate.

Schedule of Amount Recognized Before Income Tax in Accumulated Other Comprehensive Income

The following table represents amounts (before income tax impacts) included in AOCI (in the tables above), that have not yet been recognized in net periodic benefit cost:


	Year Ended December 31,
(Thousands of dollars)	2022		2021
Net actuarial loss	$	(360,113)	$	(399,010)
Prior service cost	(1,353)		(1,528)
Less: amount recognized in regulatory assets	311,124		339,356
Recognized in AOCI	$	(50,342)	$	(61,182)

Other Changes in Plan Assets and Benefit Obligations Recognized in Net Periodic Benefit Cost and Other Comprehensive Income


	Year Ended December 31,
	2022								2021								2020
(Thousands of dollars)	Total		Qualified Retirement Plan		SERP		PBOP		Total		Qualified Retirement Plan		SERP		PBOP		Total		Qualified Retirement Plan		SERP		PBOP
Net actuarial loss (gain) (a)	$	(4,079)	$	11,049	$	(6,133)	$	(8,995)	$	(59,176)	$	(54,892)	$	(3,245)	$	(1,039)	$	57,539	$	45,665	$	7,240	$	4,634
Amortization of prior service cost (b)	(175)		—		—		(175)		(959)		—		—		(959)		(1,155)		—		—		(1,155)
Amortization of net actuarial loss (b)	(34,818)		(32,468)		(2,350)		—		(44,597)		(41,955)		(2,642)		—		(37,830)		(36,025)		(1,805)		—
Prior service cost	—		—		—		—		—		—		—		—		—		—		—		—
Regulatory adjustment	28,232		19,062		—		9,170		88,194		86,196		—		1,998		(7,435)		(3,956)		—		(3,479)
Recognized in other comprehensive (income) loss	(10,840)		(2,357)		(8,483)		—		(16,538)		(10,651)		(5,887)		—		11,119		5,684		5,435		—
Net periodic benefit costs recognized in net income	47,226		41,671		4,215		1,340		57,397		51,194		4,599		1,604		56,291		50,583		3,798		1,910
Total of amount recognized in net periodic benefit cost and other comprehensive (income) loss	$	36,386	$	39,314	$	(4,268)	$	1,340	$	40,859	$	40,543	$	(1,288)	$	1,604	$	67,410	$	56,267	$	9,233	$	1,910

Background, Organization, and Summary of Significant Accounting Policies

12 Months Ended

Dec. 31, 2022

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Background, Organization, and Summary of Significant Accounting Policies

Note 1 - Background, Organization, and Summary of Significant Accounting Policies

Nature of Operations. This is a combined annual report of Southwest Gas Holdings, Inc. and its subsidiaries (the “Company”) and Southwest Gas Corporation and its subsidiaries (“Southwest” or the “natural gas distribution” segment). The notes to the consolidated financial statements apply to both entities. Southwest Gas Holdings, Inc., a Delaware corporation, is a holding company, owning all of the shares of common stock of Southwest, all of the shares of common stock of Centuri Group, Inc. (“Centuri” or the “utility infrastructure services” segment), and until February 14, 2023, all of the shares of common stock of MountainWest Pipelines Holding Company (“MountainWest” or the “pipeline and storage” segment).

In December 2022, the Company announced that its Board of Directors (the “Board”) unanimously determined to take strategic actions to simplify the Company’s portfolio of businesses. These actions included entering into a definitive agreement to sell 100% of MountainWest in an all-cash transaction to Williams Partners Operating LLC (“Williams”) for $1.5 billion in total enterprise value, subject to certain adjustments. Additionally, the Company determined it will pursue a spin-off of Centuri (the “Centuri spin-off”), to form a new independent publicly traded utility infrastructure services company. The MountainWest transaction closed on February 14, 2023, following the expiration of an applicable waiting period under the Hart-Scott-Rodino Antitrust Improvements Act of 1976. The Centuri spin-off is expected to be completed in the fourth quarter of 2023 or the first quarter of 2024 and to be tax free to the Company and its stockholders for U.S. federal income tax purposes. The Centuri spin-off will be subject to, among other things, finalizing the transaction structure, final approval by the Board, approval by the Arizona Corporation Commission, the receipt of a favorable Internal Revenue Service private letter ruling relating to the tax-free nature of the transaction, and the effectiveness of a registration statement that will be filed with the U.S. Securities and Exchange Commission. Upon classifying the pipeline and storage segment disposal group as held for sale, the Company recorded a loss, composed of a goodwill impairment loss of $449.6 million, plus an additional loss of approximately $5.8 million for estimated costs to sell, in the fourth quarter of 2022. The Company elected to not reclassify MountainWest’s assets and liabilities as held for sale as of December 31, 2021; therefore, balance sheet information as of December 31, 2021 in the accompanying notes to financial statements has not been adjusted. See Note 15 - Acquisitions and Dispositions for additional information.

Southwest is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity. Results for the natural gas distribution segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures.

Centuri is a strategic utility infrastructure services company dedicated to partnering with North America’s gas and electric providers to build and maintain the energy network that powers millions of homes across the United States (“U.S.”) and Canada. Centuri derives revenue primarily from installation, replacement, repair, and maintenance of energy networks. Centuri operates in the U.S. primarily as NPL Construction Co. (“NPL”), New England Utility Constructors, Inc. (“Neuco”), Linetec Services, LLC (“Linetec”), and Riggs Distler & Company, Inc. (“Riggs Distler”), and in Canada, primarily as NPL Canada Ltd. (“NPL Canada”). Utility infrastructure services activity is seasonal in many of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern U.S. and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round.

MountainWest includes MountainWest Pipeline, LLC, along with its subsidiary, MountainWest Overthrust Pipeline, LLC, and an equity interest in White River Hub, LLC, which is not consolidated, along with non-regulated businesses providing analytical and measurement services, and natural gas gathering.

On May 6, 2022, the Company entered into a Cooperation Agreement (the “Cooperation Agreement”) with Carl C. Icahn and the persons and entities referenced therein (collectively, the “Icahn Group”). In accordance with the Cooperation Agreement, among other things, John P. Hester, then President and Chief Executive Officer of the Company and Southwest, retired from his positions with the Company and Southwest and resigned from the Board. Karen S. Haller, the Company’s former Executive Vice President/Chief Legal and Administrative Officer, was appointed President and Chief Executive Officer of the Company and Chief Executive Officer of Southwest, and was appointed as a member of the Board effective immediately following the completion of the Company’s 2022 annual meeting of stockholders. Justin L. Brown, formerly Southwest’s Senior Vice President/General Counsel, was appointed as President of Southwest.

In addition, pursuant to the Cooperation Agreement, as modified by a letter agreement, dated as of August 3, 2022 (the "Letter Agreement" and together with the Cooperation Agreement, the "Initial Cooperation Agreement") by and between the Company and the Icahn Group, the Icahn Group has the ability to designate up to four directors to the Board (collectively, the "Icahn Designees"), subject to certain ownership thresholds. As of the date of this Annual Report on 10-K, the Icahn Designees are Andrew W. Evans, Henry P. Linginfelter, Ruby Sharma, and Andrew J. Teno.

The Initial Cooperation Agreement required the Board to expand the Strategic Transactions Committee from three directors to six directors, comprised of the existing members of the Strategic Transactions Committee in addition to the three Initial Icahn Designees. As long as the Icahn Group has the ability to designate at least three members of the Board, three of such individuals are to be included on the Strategic Transactions Committee. If the Icahn Group may only designate two members of the Board, then both would serve on the Strategic Transactions Committee.

On May 9, 2022, the Company also entered into Amendment No. 1 to the Rights Agreement dated October 10, 2021 (the “Original Rights Agreement” and as amended, the “Amended Rights Agreement”), to increase the triggering percentage from 10% to 24.9% pursuant to the terms of the Initial Cooperation Agreement and permit the subsequent consummation of the Offer. The Amended Rights Agreement expired on October 9, 2022. The Company filed a Certificate of Elimination with the Secretary of State of the State of Delaware on January 13, 2023, eliminating from the Company's Certificate of Incorporation the Certificate of Designation of Series A Junior Participating Preferred Stock filed on October 10, 2022, and the associated Preferred Stock Purchase Rights were deregistered by the SEC and delisted by the New York Stock Exchange on the same day.

An earlier civil suit (initiated in November 2021) by Icahn entities against the Company and certain directors and officers of the Company was subject to a stipulation of dismissal as part of the Initial Cooperation Agreement, which also provided for the reimbursement by the Company of certain out-of-pocket third-party expenses, including certain legal fees, incurred by the Icahn Group.

On October 24, 2022, the Company and the Icahn Group entered into an Amended and Restated Cooperation Agreement (the “Amended Cooperation Agreement”), which amended, restated, superseded, and replaced in its entirety the Initial Cooperation Agreement. Among other things, the Amended Cooperation Agreement provides for the nomination of the Icahn Designees for election at the Company's 2023 annual meeting of stockholders (the "2023 Annual Meeting"), the extension of the standstill restrictions on the Icahn Group through the 2023 Annual Meeting or the Company's 2024 annual meeting of stockholders, subject to certain restrictions and exceptions, and subject to certain ownership thresholds by the Icahn Group and the approval by the Strategic Transactions Committee, certain aspects of the corporate structure and conduct of the first annual meeting of any independent, publicly traded company resulting from a separation of the Company's businesses.

Basis of Presentation. The Company follows accounting principles generally accepted in the United States (“U.S. GAAP”) in accounting for all of its businesses. Unless specified otherwise, all amounts are in U.S. dollars. Accounting for regulated operations conforms with U.S. GAAP as applied to rate-regulated companies and as prescribed by federal agencies and commissions of the various states in which the rate-regulated companies operate. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

Consolidation. The accompanying financial statements (as of and for the periods presented) are presented on a consolidated basis for Southwest Gas Holdings, Inc. and all subsidiaries and Southwest Gas Corporation and all subsidiaries (except those accounted for using the equity method as discussed below). All significant intercompany balances and transactions have been eliminated with the exception of transactions between Southwest and Centuri in accordance with accounting treatment for rate-regulated entities.

Centuri, through its subsidiaries, holds a 50% interest in W.S. Nicholls Western Construction Ltd. (“Western”), a Canadian infrastructure services company that is a variable interest entity. Centuri determined that it is not the primary beneficiary of the entity due to a shared-power structure; therefore, Centuri does not consolidate the entity and has recorded its investment, and results related thereto, using the equity method. The investment in Western, related earnings, and dividends received from Western in 2022 and 2021 were not significant. Centuri’s maximum exposure to loss as a result of its involvement with Western was estimated at $11.4 million as of December 31, 2022.

MountainWest, through its subsidiaries, holds a 50% noncontrolling interest in MountainWest White River Hub, LLC, a FERC-regulated transporter of natural gas with facilities that connect with six interstate pipeline systems and a major processing plant in Colorado. As noted above, MountainWest does not consolidate the entity and has recorded its investment using the equity method. The investment in White River Hub is approximately $25 million as of December 31, 2022 and the related proportional earnings and dividends in 2022 were not significant to the Company.

Fair Value Measurements. Certain assets and liabilities are reported at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date.

U.S. GAAP states that a fair value measurement should be based on the assumptions that market participants would use in pricing the asset or liability and establishes a fair value hierarchy that ranks the inputs used to measure fair value by their reliability. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities

(Level 1 measurements) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurements). Financial assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows:

Level 1 – quoted prices (unadjusted) in active markets for identical assets or liabilities that a company has the ability to access at the measurement date.

Level 2 – inputs other than quoted prices included within Level 1 that are observable for similar assets or liabilities, either directly or indirectly.

Level 3 – unobservable inputs for the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date.

The Company primarily used quoted market prices and other observable market pricing information (exclusive of any purchase accounting adjustments) in valuing cash and cash equivalents, long-term debt outstanding, and assets of the qualified pension plan and the postretirement benefits other than pensions required to be recorded and/or disclosed at fair value. The Company uses prices and inputs that are current as of the measurement date, and recognizes transfers between levels at either the actual date of an event or a change in circumstance that caused the transfer.

Net Regulated Operations Plant. Net regulated operations plant includes gas plant at original cost, less the accumulated provision for depreciation and amortization, plus any unamortized balance of acquisition adjustments. Original cost generally includes contracted services, material, payroll, and related costs such as taxes and certain benefits, general and administrative expenses, and an allowance for funds used during construction, less contributions in aid of construction. Aligned with regulatory treatment, when plant is retired, the cost of such plant, net of any salvage value, is charged to accumulated depreciation. See also Depreciation and Amortization below.

Other Property and Investments. Other property and investments on Southwest’s and the Company’s Consolidated Balance Sheets includes:


	December 31,
(Thousands of dollars)	2022		2021
Net cash surrender value of COLI policies	$	136,245	$	149,947
Other property	33,152		3,146
Total Southwest Gas Corporation	169,397		153,093
Non-regulated property, equipment, and intangibles	1,677,218		1,616,392
Non-regulated accumulated provision for depreciation and amortization	(596,518)		(512,343)
Other property and investments	31,075		59,337
Total Southwest Gas Holdings, Inc.	$	1,281,172	$	1,316,479

Included in the table above are the net cash surrender values of company-owned life insurance (“COLI”) policies. These life insurance policies on members of management and other key employees are used by Southwest to indemnify itself against the loss of talent, expertise, and knowledge, as well as to provide indirect funding for certain nonqualified benefit plans. The term non-regulated in regard to assets and related balances in the table above is in reference to the non-rate regulated operations of Centuri, and to a more limited extent, MountainWest as of year-end 2021. MountainWest is not reflected in the table above as of December 31, 2022, since the balance has been reclassified as held for sale on the Company’s Consolidated Balance sheet as of that date. See Note 15 - Acquisitions and Dispositions for additional information.

Intangible Assets. Intangible assets (other than goodwill) are amortized using the straight-line method to reflect the pattern of economic benefits consumed over the estimated periods benefited. The recoverability of intangible assets is evaluated when events or circumstances indicate that a revision of estimated useful lives is warranted or that an intangible asset may be impaired. These intangible assets are included in Other property and investments on the Company’s Consolidated Balance

Sheets. Centuri’s intangible assets (other than goodwill) have finite lives and are associated with businesses previously acquired. The balances at December 31, 2022 and 2021, respectively, were as follows:


	December 31, 2022
(Thousands of dollars)	Gross Carrying Amount		Accumulated Amortization		Net Carrying Amount
Customer relationships	$	391,758	$	(63,509)	$	328,249
Trade names and trademarks	79,277		(12,278)		66,999

Total	$	471,035	$	(75,787)	$	395,248

	December 31, 2021
Customer relationships	$	393,834	$	(42,886)	$	350,948
Trade names and trademarks	79,650		(7,093)		72,557
Customer contracts backlog	4,500		(1,500)		3,000
Total	$	477,984	$	(51,479)	$	426,505

Amortization expense for the acquired intangible assets listed above for the years ended December 31, 2022, 2021, and 2020 was $29.8 million, $17.3 million, and $10.8 million, respectively. The weighted-average amortization periods for customer relationships, trade names and trademarks, and customer contracts backlog are 19 years, 15 years, and 1 year, respectively.

The estimated future amortization of the intangible assets for the next five years and thereafter is as follows:


(Thousands of dollars)
2023	$	26,690
2024	26,690
2025	26,678
2026	26,455
2027	26,088
Thereafter	262,647
Total	$	395,248

See Note 2 - Regulated Operations Plant and Leases for additional information regarding natural gas distribution intangible assets.

Cash and Cash Equivalents. For purposes of reporting consolidated cash flows, cash and cash equivalents include cash on hand and financial instruments with original maturities of three months or less. Such investments are carried at cost, which approximates market value. Cash and cash equivalents of the Company include $30 million of money market fund investments at December 31, 2022, and $20 million at December 31, 2021. The money market fund investments for Southwest were $17.6 million at December 31, 2022 and insignificant at December 31, 2021. These investments fall within Level 2 of the fair value hierarchy, due to the asset valuation methods used by money market funds.

Noncash investing activities for the Company and Southwest include capital expenditures that were not yet paid as of year end, thereby remaining in accounts payable, the amounts related to which increased by approximately $23.4 million and $19.7 million, for the Company and Southwest, respectively during the year ended December 31, 2022, and $15.5 million and $13.9 million, for the Company and Southwest, respectively, during the year ended December 31, 2021. Additionally for Southwest, noncash investing activities include customer advances applied as contributions toward utility construction activity, such amounts were not significant for the periods presented herein. Also, see Note 2 - Regulated Operations Plant and Leases for information related to right-of-use (“ROU”) assets obtained in exchange for lease liabilities, which are noncash investing and financing activities. ROU assets and lease liabilities are also subject to noncash impacts as a result of other factors, such as lease terminations and modifications.

Income Taxes. The asset and liability method of accounting is utilized for the recognition of income taxes. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are anticipated to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. For regulatory and financial reporting purposes, investment tax credits (“ITC”) related to gas utility operations are deferred and amortized over the life of related fixed assets.

As of December 31, 2022, the Company had cumulative book earnings of approximately $79 million in its foreign jurisdiction. Management previously asserted and continues to assert that all the earnings of Centuri’s Canadian subsidiaries will be permanently reinvested in Canada. As a result, no U.S. deferred income taxes have been recorded related to cumulative foreign earnings.

The Financial Accounting Standards Board (the “FASB”) issued guidance to allow an accounting policy election of either (i) treating taxes attributable to future taxable income related to Global Intangible Low-Taxed Income (“GILTI”) as a current period expense when incurred or (ii) recognizing deferred taxes for temporary differences expected to reverse as GILTI in future years. The Company has elected to treat GILTI as a current period cost when incurred and has considered the estimated 2022 GILTI impact to its 2022 tax expense, which was immaterial.

Deferred Purchased Gas Costs. The various regulatory commissions have established procedures to enable the rate-regulated companies to adjust billing rates for changes in the cost of natural gas purchased. The difference between the current cost of gas purchased and the cost of gas recovered in billed rates is deferred. Generally, these deferred amounts are recovered or refunded within one year.

Prepaid and other current assets. Prepaid and other current assets for Southwest and the Company include, among other things, accrued purchased gas costs of $207 million in 2022 and $52 million in 2021. Additionally, Southwest had gas pipe materials and operating supplies of $77.3 million in 2022 and $62.9 million in 2021 (carried at weighted average cost). MountainWest’s materials and supplies were immaterial in the 2021 period in which they were included in the balance of Prepaid and other current assets in regard to the Company.

Held for sale. The Company and Southwest recognize the assets and liabilities of a disposal group as held for sale in the period (i) it has approved and committed to a plan to sell the disposal group, (ii) the disposal group is available for immediate sale in its present condition, (iii) an active program to locate a buyer and other actions to sell the disposal group have been initiated, (iv) it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. The Company and Southwest initially measure a disposal group that is classified as held for sale at the lower of its carrying value or fair value less any costs to sell. Any loss resulting from this measurement is recognized in the period in which the held for sale criteria are met. Conversely, gains are not recognized on the sale of a disposal group until closing. Upon designation as held for sale, the Company and Southwest stop recording depreciation expense and assess the fair value of the disposal group less any costs to sell at each reporting period, until it is no longer classified as held for sale. See Note 15 - Acquisitions and Dispositions for information related to the MountainWest assets and liabilities held for sale.

The Company and Southwest had earlier classified certain assets associated with its previous corporate headquarters as held for sale. The sale was not completed and management determined that the assets no longer meet the criteria to be classified as held for sale. As a result, the Company and Southwest reclassified approximately $27 million from Prepaid and other current assets to Other property and investments on their respective Consolidated Balance Sheets during the fourth quarter of 2022. Southwest also received an updated appraisal on these assets, and as a result, recorded a loss of $2.9 million in the fourth quarter of 2022.

Goodwill. As required by U.S. GAAP, goodwill is assessed for impairment annually, or more frequently, if circumstances indicate impairment to the carrying value of goodwill may have occurred. The goodwill impairment analysis was conducted as of October 1st using a qualitative assessment, as permitted by U.S. GAAP. Management of the Company and Southwest considered its reporting units and segments, determining that they remained consistent between periods presented below, and that no change was necessary with regard to the level at which goodwill is assessed for impairment. The acquisition of MountainWest resulted in a new reportable segment, which was assessed for impairment beginning in 2022, and upon being classified as held for sale, an impairment was recognized, as outlined below. The Company and Southwest determined that it is not more likely than not that the fair values of the Centuri and Southwest reporting units were less than their carrying amounts in either 2022 or 2021, and therefore, no impairment was recorded in either year in regard to these entities.

In regard to MountainWest, and the agreement to sell the equity interests to Williams, which was undertaken to simplify the Company’s business overall and ultimately position it as a pure-play local distribution company, management considered the expected proceeds, which were below the carrying value of the equity interests at that time; as such, a loss was recognized, recorded primarily as a goodwill impairment of $449.6 million in the fourth quarter of 2022. See Note 15 - Acquisitions and Dispositions for additional information. Additional losses are possible through the post-closing process for MountainWest, as customary final adjustments are made. There can also be no assurances that future assessments of remaining goodwill on the Company’s and Southwest’s balance sheets will not result in an impairment; various factors, including the planned spin-off of Centuri, or changes in economic conditions, governmental monetary policies, interest rates, or others, on their own or in combination, could result in the fair value of the related reporting units being lower than their carrying value.

Goodwill in the Natural Gas Distribution and Utility Infrastructure Services segments is included in their respective Consolidated Balance Sheets as follows:


(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Total Company
Balance, December 31, 2020	$	10,095	$	335,089	$	345,184
Additional goodwill from Riggs Distler acquisition	—		449,501		449,501
Foreign currency translation adjustment	—		468		468
Balance, December 31, 2021	10,095		785,058		$	795,153
Additional goodwill from Graham County acquisition	1,060		—		1,060
Measurement-period adjustments from Riggs Distler acquisition	—		(1,924)		(1,924)
Foreign currency translation adjustment	—		(7,039)		(7,039)
Balance, December 31, 2022	$	11,155	$	776,095	$	787,250

Goodwill related to the pipeline and storage segment, which as of December 31, 2021 was $986.2 million, is not reflected in the above table as the balance has been reclassified as held for sale on the Company’s Consolidated Balance sheet as of December 31, 2022. See Note 15 - Acquisitions and Dispositions for additional information.

Other Current Liabilities. Management recognizes in its balance sheets various liabilities that are expected to be settled through future cash payment within the next twelve months, including certain regulatory mechanisms (refer to Note 5 - Regulatory Assets and Liabilities), customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities. Other current liabilities for the Company include $41.6 million and $36 million of dividends declared as of December 31, 2022 and 2021, respectively.

Accumulated Removal Costs. Approved regulatory practices allow Southwest to include in depreciation expense a component intended to recover removal costs associated with regulated operations plant retirements. In accordance with the Securities and Exchange Commission (“SEC”) position on presentation of these amounts, management reclassifies estimated removal costs from Accumulated depreciation to Accumulated removal costs within the liabilities section of the Consolidated Balance Sheets. Management regularly updates the estimated accumulated removal costs as amounts fluctuate between periods depending on the level of replacement work performed (and actual cost experience) compared to the estimated cost of removal in rates.

Gas Operating Revenues. Southwest recognizes revenue when it satisfies its performance by transferring gas to the customer. Natural gas is delivered and “consumed” by the customer simultaneously. Revenues are recorded when customers are billed. Customer billings are substantially based on monthly meter reads and include certain other charges assessed monthly, and are calculated in accordance with applicable tariffs and state and local laws, regulations, and related agreements. An estimate of the margin associated with natural gas service provided, but not yet billed, to residential and commercial customers from the latest meter read date to the end of the reporting period is also recognized as accrued utility revenue. Revenues also include the net impacts of margin tracker/decoupling accruals based on criteria in U.S. GAAP for rate-regulated entities associated with alternative revenue programs. All of Southwest’s service territories have decoupled rate structures, which are designed to eliminate the direct link between volumetric sales and revenue, thereby mitigating the impacts of unusual weather variability and conservation on margin. See Note 3 - Revenue for additional information and also a description of MountainWest’s revenues.

Utility Infrastructure Services Revenues. The majority of Centuri contracts are performed under unit-price contracts. Generally, these contracts state prices per unit of installation. Typical installations are accomplished in a few weeks or less. Revenues are recorded as installations are completed. Revenues are recorded for long-term fixed-price contracts in a pattern that reflects the transfer of control of promised goods and services to the customer over time. The amount of revenue recognized on fixed-price contracts is based on costs expended to date relative to anticipated final contract costs. Changes in job performance, job conditions, and final contract settlements are factors that influence management’s assessment of total contract value and the total estimated costs to complete those contracts. Revisions in estimates of costs and earnings during the course of work are reflected in the accounting period in which the facts requiring revision become known. If a loss on a contract becomes known or is anticipated, the entire amount of the estimated ultimate loss is recognized at that time in the financial statements. Some unit-price contracts contain caps that if encroached, trigger revenue and loss recognition similar to a fixed-price contract model. See Note 3 - Revenue.

Intercompany Transactions. Centuri recognizes revenues generated from contracts with Southwest (see Note 13 - Segment Information). The accounts receivable balance, revenues, and associated profits are included in the consolidated financial statements of the Company and Southwest and are not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities.

Utility Infrastructure Services Expenses. Centuri’s utility infrastructure services expenses in the Consolidated Statements of Income includes payroll expenses, office and equipment rental costs, subcontractor expenses, training, job-related materials, gains and losses on equipment sales, and professional fees.

Net Cost of Gas Sold. Components of net cost of gas sold include natural gas commodity costs (fixed-price and variable-rate), pipeline capacity/transportation costs, and any actual settled costs of natural gas derivative instruments, where relevant. Also included are the net impacts of PGA deferrals and recoveries, which by their inclusion, result in net cost of gas sold overall that is comparable to amounts included in billed gas operating revenues. Differences between amounts incurred with suppliers, transmission pipelines, etc. and amounts already included in customer rates, are temporarily deferred in PGA accounts pending inclusion in customer rates.

Operations and Maintenance Expense. Operations and maintenance expense includes Southwest’s operating and maintenance costs associated with serving utility customers and maintaining its distribution and transmission systems, uncollectible customer accounts expense, administrative and general salaries and expense, employee benefits expense excluding relevant non-service cost components, legal expense (including injuries and damages), professional and other external contracted services, and other business expenses. Also included are similar costs for MountainWest.

Depreciation and Amortization. Regulated operations plant depreciation is computed on the straight-line remaining life method at composite rates considered sufficient to amortize costs over estimated service lives, including components which compensate for removal costs (net of salvage value), and retirements, as approved by the appropriate regulatory agency. When plant is retired from service, the original cost of plant, including cost of removal, less salvage, is charged to the accumulated provision for depreciation. See also discussion regarding Accumulated Removal Costs above. Other regulatory assets, including acquisition adjustments, are amortized when appropriate, over time periods authorized by regulators. Non-regulated operations, including utility infrastructure services-related property and equipment, are depreciated on a straight-line method based on the estimated useful lives of the related assets. Costs and gains related to refunding regulated operations debt and debt issuance expenses are deferred and amortized over the weighted-average lives of the new issues and become a component of interest expense.

Allowance for Funds Used During Construction (“AFUDC”). AFUDC represents the cost of both debt and equity funds used to finance regulated operations plant construction. AFUDC is capitalized as part of the cost of regulated operations plant. The debt portion of AFUDC is reported in the Company’s and Southwest’s Consolidated Statements of Income as an offset to Net interest deductions and the equity portion is reported as Other income. Regulated operations plant construction costs, including AFUDC, are recoverable as part of authorized rates through depreciation when completed projects are placed into operation, and general rate relief is requested and granted. AFUDC, disaggregated by type, included in the Company’s and Southwest’s Consolidated Statements of Income are presented in the table below:


(Thousands of dollars)	2022			2021			2020
AFUDC:
Debt portion	$	3,535		$	1,046		$	3,202
Equity portion	—			—			4,724
AFUDC capitalized as part of regulated operations plant	$	3,535		$	1,046		$	7,926
AFUDC rate	2.64		%	0.96		%	5.51		%

AFUDC related to MountainWest includes $86,000 of debt and $465,000 of equity during the year ended December 31, 2022, which is not reflected in the table above. Debt and equity AFUDC at Southwest were impacted in 2022 and 2021 by the amount of short-term debt outstanding based on the regulatory formula for each component.

Other Income (Deductions). The following table provides the composition of significant items included in Other income (deductions) on the Consolidated Statements of Income:


(Thousands of dollars)	2022		2021		2020
Southwest Gas Corporation:
Change in COLI policies	$	(5,400)	$	8,800	$	9,200
Interest income	16,183		5,113		4,015
Equity AFUDC	—		—		4,724
Other components of net periodic benefit cost	(751)		(14,021)		(20,022)
Miscellaneous income and (expense)	(16,916)		(4,451)		(4,507)
Southwest Gas Corporation – total other income (deductions)	(6,884)		(4,559)		(6,590)
Centuri, MountainWest, and Southwest Gas Holdings, Inc.:

Foreign transaction gain (loss)	977		(22)		(16)
Equity AFUDC	465		—		—
Equity in earnings of unconsolidated investments	2,629		226		80
Miscellaneous income and (expense)	(3,113)		863		(271)
Corporate and administrative	(263)		$	(7)	$	8
Southwest Gas Holdings, Inc. - total other income (deductions)	$	(6,189)	$	(3,499)	$	(6,789)

Included in the table above is the change in COLI policies (including net death benefits recognized, where relevant). Current tax regulations provide for tax-free treatment of life insurance (death benefit) proceeds. Therefore, changes in the cash surrender value components of COLI policies, as they progress towards the ultimate death benefits, are also recorded without tax consequences. Miscellaneous income and (expense) in 2022 includes the reduction in value of Southwest’s previous corporate campus property.

Derivatives. In managing its natural gas supply portfolios, Southwest has historically entered into fixed- and variable-price contracts, which qualify as derivatives. The fixed-price contracts, firm commitments to purchase a fixed amount of gas in the future at a fixed price, qualify for the normal purchases and normal sales exception that is allowed for contracts that are probable of delivery in the normal course of business, and are exempt from fair value reporting. The variable-price contracts qualify as derivative instruments; however, because the contract price is the prevailing price at the future transaction date, no fair value adjustment is required. Southwest does not utilize derivative financial instruments for speculative purposes, nor does it have trading operations.

Foreign Currency Translation and Transactions. Foreign currency-denominated assets and liabilities of consolidated subsidiaries are translated into U.S. dollars at exchange rates existing at the respective balance sheet dates. Translation adjustments resulting from fluctuations in exchange rates are recorded as a separate component of accumulated other comprehensive income within stockholders’ equity. Results of operations of foreign subsidiaries are translated using the monthly weighted-average exchange rates during the respective periods. Gains and losses resulting from foreign currency transactions are included in Other income and (expenses) of the Company. Gains and losses resulting from intercompany foreign currency transactions that are of a long-term investment nature are reported in Other comprehensive income, if applicable.

Earnings (Loss) Per Share. Basic earnings (loss) per share (“EPS”) in each period of this report were calculated by dividing net income (loss) attributable to Southwest Gas Holdings, Inc. by the weighted-average number of shares during those periods. Diluted EPS includes additional weighted-average common stock equivalents (performance shares and restricted stock units), if dilutive. Unless otherwise noted, the term “Earnings Per Share” refers to Basic EPS. A reconciliation of the denominator used in Basic and Diluted EPS calculations is shown in the following table:


(In thousands)	2022	2021	2020
Weighted average basic shares	65,558	59,145	55,998
Effect of dilutive securities:
Restricted stock units (1)(2)	—	114	78
Weighted average diluted shares	65,558	59,259	56,076

(1) The number of anti-dilutive restricted stock units for 2022 excluded from the calculation of diluted shares is 157,000.

Recent Accounting Standards Updates.

Accounting pronouncements effective or adopted in 2022:

In March 2020, the FASB issued Accounting Standards Update (“ASU”) 2020-04 “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The update provides optional guidance for a limited time to ease the potential burden in accounting for, or recognizing the effects of, reference rate reform on financial reporting, including when modifying a contract (during the eligibility period covered by the update to the topic) to replace a reference rate affected by reference rate reform. The update applies only to contracts and hedging relationships that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued due to reference rate reform. The guidance was eligible to be applied upon issuance on March 12, 2020, and can generally be applied through December 31, 2022. In December 2022, the FASB issued ASU 2022-06 “Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848.” The update provides deferral of the sunset date of Topic 848 from December 31, 2022 to December 31, 2024. Management will continue to monitor the impacts this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures, and will reflect such appropriately, in the event that the optional guidance is elected. See also LIBOR discussion in Note 8 - Debt.

In August 2020, the FASB issued ASU 2020-06 “Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging— Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity.” The update, amongst other amendments, improves the guidance related to the disclosures and earnings per share for convertible instruments and contracts in an entity’s own equity. The Company and Southwest adopted the update in the first quarter of 2022, the impact of which was not material to the consolidated financial statements of the Company or Southwest.

There are no other recently issued accounting standards updates that are expected to be adopted or material to Southwest or the Company effective in 2023 or thereafter.

Subsequent Events. Management monitors events occurring after the balance sheet date and prior to the issuance of the financial statements to determine the impacts, if any, of events on the financial statements to be issued or disclosures to be made, and has reflected them where appropriate. See Note 1 - Background, Organization, and Summary of Significant Accounting Policies, Note 8 - Debt, and Note 15 - Acquisitions and Dispositions.

Revenue - Schedule of Regulated Operations Revenues: Utility Infrastructure Services Segment (Details) - Centuri - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 2,760,327	$ 2,158,661	$ 1,948,288
Master services agreement
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	2,342,220	1,652,978	1,490,009
Bid contract
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	418,107	505,683	458,279
Unit-price contracts
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,608,131	1,369,082	1,356,640
Fixed-price contracts
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	498,039	267,742	157,701
Time and materials contracts
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	654,157	521,837	433,947
Gas infrastructure services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	1,531,818	1,302,340	1,261,160
Electric power infrastructure services
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	778,124	525,202	411,826
Other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 450,385	$ 331,119	$ 275,302

Share-Based Compensation - Narrative (Details) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Compensation expense	$ 9,446	$ 9,294	$ 7,114
Compensation cost related to nonvested management incentive plan shares, performance shares, and restricted stock/units not yet recognized	$ 5,300
Compensation cost not yet recognized, period for recognition	2 years 4 months 24 days
Omnibus Incentive Plan \| Performance Shares
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Performance measurement period	3 years
Compensation expense	$ 2,100	$ 3,400	$ 2,800
Restricted Stock/Unit Plan
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Weighted average grant date fair value (in USD per share)	$ 66.11	$ 65.38	$ 76.85
Restricted Stock/Unit Plan \| Vesting Tranche One
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	40.00%
Restricted Stock/Unit Plan \| Vesting Tranche Two
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	30.00%
Restricted Stock/Unit Plan \| Vesting Tranche Three
Share-based Compensation Arrangement by Share-based Payment Award [Line Items]
Award vesting percentage	30.00%

Income Taxes - Summary of Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Current:
Federal	$ (949)	$ (2,872)	$ 6,287
State	7,123	(11,516)	8,617
Foreign	9,089	6,524	4,666
Total current income tax expense	15,263	(7,864)	19,570
Deferred:
Federal	(76,984)	39,117	44,547
State	(12,828)	8,239	414
Foreign	(1,104)	156	1,222
Total deferred income tax expense (benefit)	(90,916)	47,512	46,183
Total income tax expense (benefit)	(75,653)	39,648	65,753
Southwest Gas Corporation
Current:
Federal	(78)	(3,643)	(4,678)
State	7,805	(6,556)	(179)
Total current income tax expense	7,727	(10,199)	(4,857)
Deferred:
Federal	23,710	36,842	38,561
State	(896)	2,695	2,051
Total deferred income tax expense (benefit)	22,814	39,537	40,612
Total income tax expense (benefit)	$ 30,541	$ 29,338	$ 35,755

Redeemable Noncontrolling Interests - Narrative (Details) - USD ($) $ in Thousands	1 Months Ended		12 Months Ended
	Mar. 31, 2022	Nov. 30, 2021	Dec. 31, 2022	Dec. 31, 2021	Nov. 30, 2018
Noncontrolling Interest [Line Items]
Percentage of redeemable noncontrolling interest redeemed	5.00%
Percentage of interest retained by noncontrolling party subject to election			100.00%
Redemption value adjustments			$ (3,325)	$ 12,016
Promissory Note \| Prime Rate
Noncontrolling Interest [Line Items]
Debt, basis spread on variable rate		2.00%
Centuri
Noncontrolling Interest [Line Items]
Payments for redemption of redeemable noncontrolling interest	$ 39,600
Linetec
Noncontrolling Interest [Line Items]
Redemption value adjustments			(3,325)	12,016
Linetec \| Previous Owner Of Linetec
Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners	15.00%				20.00%
Drum
Noncontrolling Interest [Line Items]
Redemption value adjustments			$ 0	$ 0
Drum \| Certain Members Of Riggs Distler Management
Noncontrolling Interest [Line Items]
Ownership percentage by noncontrolling owners		1.42%

Regulatory Assets and Liabilities - Schedule of Components of Other Regulatory Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
State mandated public purpose programs (including low income and conservation programs)
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 1,567	$ 1,886
State mandated public purpose programs (including low income and conservation programs) \| Southwest Gas Corporation
Regulatory Liabilities [Line Items]
Regulatory liabilities		1,886
Environmental compliance programs
Regulatory Liabilities [Line Items]
Regulatory liabilities	0	4,182
Environmental compliance programs \| Southwest Gas Corporation
Regulatory Liabilities [Line Items]
Regulatory liabilities		4,182
Other Miscellaneous Regulatory Liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities	3,826	4,253
Other Miscellaneous Regulatory Liabilities \| Southwest Gas Corporation
Regulatory Liabilities [Line Items]
Regulatory liabilities		2,505
Other
Regulatory Liabilities [Line Items]
Regulatory liabilities	5,393	10,321
Other \| Other deferred credits and other long-term liabilities
Regulatory Liabilities [Line Items]
Regulatory liabilities	$ 823
Other \| Southwest Gas Corporation
Regulatory Liabilities [Line Items]
Regulatory liabilities		$ 8,573

Segment Information - Schedule of Revenues by Geographic Area (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 4,960,009	$ 3,680,451	$ 3,298,873
United States
Segment Reporting Information [Line Items]
Revenues	4,637,557	3,411,018	3,057,041
Canada
Segment Reporting Information [Line Items]
Revenues	$ 322,452	$ 269,433	$ 241,832

Pension and Other Postretirement Benefits - Schedule of Assumptions Used (Details) - Southwest Gas Corporation	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Defined Benefit Plan Disclosure [Line Items]
Discount rate	5.25%	3.00%
Weighted-average rate of compensation increase	3.25%	3.25%
Asset return assumption	6.75%	6.50%

Background, Organization, and Summary of Significant Accounting Policies (Policies)	12 Months Ended
	Dec. 31, 2022
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Nature of Operations	Nature of Operations. This is a combined annual report of Southwest Gas Holdings, Inc. and its subsidiaries (the “Company”) and Southwest Gas Corporation and its subsidiaries (“Southwest” or the “natural gas distribution” segment). The notes to the consolidated financial statements apply to both entities. Southwest Gas Holdings, Inc., a Delaware corporation, is a holding company, owning all of the shares of common stock of Southwest, all of the shares of common stock of Centuri Group, Inc. (“Centuri” or the “utility infrastructure services” segment), and until February 14, 2023, all of the shares of common stock of MountainWest Pipelines Holding Company (“MountainWest” or the “pipeline and storage” segment). Southwest is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Public utility rates, practices, facilities, and service territories of Southwest are subject to regulatory oversight. The timing and amount of rate relief can materially impact results of operations. Natural gas purchases and the timing of related recoveries can materially impact liquidity. Results for the natural gas distribution segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures. Centuri is a strategic utility infrastructure services company dedicated to partnering with North America’s gas and electric providers to build and maintain the energy network that powers millions of homes across the United States (“U.S.”) and Canada. Centuri derives revenue primarily from installation, replacement, repair, and maintenance of energy networks. Centuri operates in the U.S. primarily as NPL Construction Co. (“NPL”), New England Utility Constructors, Inc. (“Neuco”), Linetec Services, LLC (“Linetec”), and Riggs Distler & Company, Inc. (“Riggs Distler”), and in Canada, primarily as NPL Canada Ltd. (“NPL Canada”). Utility infrastructure services activity is seasonal in many of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern U.S. and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round. MountainWest includes MountainWest Pipeline, LLC, along with its subsidiary, MountainWest Overthrust Pipeline, LLC, and an equity interest in White River Hub, LLC, which is not consolidated, along with non-regulated businesses providing analytical and measurement services, and natural gas gathering.
Basis of Presentation	Basis of Presentation. The Company follows accounting principles generally accepted in the United States (“U.S. GAAP”) in accounting for all of its businesses. Unless specified otherwise, all amounts are in U.S. dollars. Accounting for regulated operations conforms with U.S. GAAP as applied to rate-regulated companies and as prescribed by federal agencies and commissions of the various states in which the rate-regulated companies operate. The preparation of financial statements in conformity with U.S. GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.
Consolidation	Consolidation. The accompanying financial statements (as of and for the periods presented) are presented on a consolidated basis for Southwest Gas Holdings, Inc. and all subsidiaries and Southwest Gas Corporation and all subsidiaries (except those accounted for using the equity method as discussed below). All significant intercompany balances and transactions have been eliminated with the exception of transactions between Southwest and Centuri in accordance with accounting treatment for rate-regulated entities. Centuri, through its subsidiaries, holds a 50% interest in W.S. Nicholls Western Construction Ltd. (“Western”), a Canadian infrastructure services company that is a variable interest entity. Centuri determined that it is not the primary beneficiary of the entity due to a shared-power structure; therefore, Centuri does not consolidate the entity and has recorded its investment, and results related thereto, using the equity method. The investment in Western, related earnings, and dividends received from Western in 2022 and 2021 were not significant. Centuri’s maximum exposure to loss as a result of its involvement with Western was estimated at $11.4 million as of December 31, 2022. MountainWest, through its subsidiaries, holds a 50% noncontrolling interest in MountainWest White River Hub, LLC, a FERC-regulated transporter of natural gas with facilities that connect with six interstate pipeline systems and a major processing plant in Colorado. As noted above, MountainWest does not consolidate the entity and has recorded its investment using the equity method. The investment in White River Hub is approximately $25 million as of December 31, 2022 and the related proportional earnings and dividends in 2022 were not significant to the Company.
Fair Value Measurements	Fair Value Measurements. Certain assets and liabilities are reported at fair value, which is defined as the price that would be received to sell an asset or paid to transfer a liability in an orderly transaction between market participants at the measurement date. U.S. GAAP states that a fair value measurement should be based on the assumptions that market participants would use in pricing the asset or liability and establishes a fair value hierarchy that ranks the inputs used to measure fair value by their reliability. The hierarchy gives the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities (Level 1 measurements) and the lowest priority to fair values derived from unobservable inputs (Level 3 measurements). Financial assets and liabilities are categorized in their entirety based on the lowest level of input that is significant to the fair value measurement. The three levels of the fair value hierarchy are as follows: Level 1 – quoted prices (unadjusted) in active markets for identical assets or liabilities that a company has the ability to access at the measurement date. Level 2 – inputs other than quoted prices included within Level 1 that are observable for similar assets or liabilities, either directly or indirectly. Level 3 – unobservable inputs for the asset or liability. Unobservable inputs are used to measure fair value to the extent that observable inputs are not available, thereby allowing for situations in which there is little, if any, market activity for the asset or liability at the measurement date. The Company primarily used quoted market prices and other observable market pricing information (exclusive of any purchase accounting adjustments) in valuing cash and cash equivalents, long-term debt outstanding, and assets of the qualified pension plan and the postretirement benefits other than pensions required to be recorded and/or disclosed at fair value. The Company uses prices and inputs that are current as of the measurement date, and recognizes transfers between levels at either the actual date of an event or a change in circumstance that caused the transfer.
Net Regulated Operations Plant	Net Regulated Operations Plant. Net regulated operations plant includes gas plant at original cost, less the accumulated provision for depreciation and amortization, plus any unamortized balance of acquisition adjustments. Original cost generally includes contracted services, material, payroll, and related costs such as taxes and certain benefits, general and administrative expenses, and an allowance for funds used during construction, less contributions in aid of construction.
Intangible Assets	Intangible Assets. Intangible assets (other than goodwill) are amortized using the straight-line method to reflect the pattern of economic benefits consumed over the estimated periods benefited. The recoverability of intangible assets is evaluated when events or circumstances indicate that a revision of estimated useful lives is warranted or that an intangible asset may be impaired. These intangible assets are included in Other property and investments on the Company’s Consolidated Balance Sheets.
Cash and Cash Equivalents	Cash and Cash Equivalents. For purposes of reporting consolidated cash flows, cash and cash equivalents include cash on hand and financial instruments with original maturities of three months or less. Such investments are carried at cost, which approximates market value. Cash and cash equivalents of the Company include $30 million of money market fund investments at December 31, 2022, and $20 million at December 31, 2021. The money market fund investments for Southwest were $17.6 million at December 31, 2022 and insignificant at December 31, 2021. These investments fall within Level 2 of the fair value hierarchy, due to the asset valuation methods used by money market funds. Noncash investing activities for the Company and Southwest include capital expenditures that were not yet paid as of year end, thereby remaining in accounts payable, the amounts related to which increased by approximately $23.4 million and $19.7 million, for the Company and Southwest, respectively during the year ended December 31, 2022, and $15.5 million and $13.9 million, for the Company and Southwest, respectively, during the year ended December 31, 2021. Additionally for Southwest, noncash investing activities include customer advances applied as contributions toward utility construction activity, such amounts were not significant for the periods presented herein. Also, see Note 2 - Regulated Operations Plant and Leases for information related to right-of-use (“ROU”) assets obtained in exchange for lease liabilities, which are noncash investing and financing activities. ROU assets and lease liabilities are also subject to noncash impacts as a result of other factors, such as lease terminations and modifications.
Income Taxes	Income Taxes. The asset and liability method of accounting is utilized for the recognition of income taxes. Under the asset and liability method, deferred tax assets and liabilities are recognized for the future tax consequences attributable to differences between the financial statement carrying amounts of existing assets and liabilities and their respective tax bases. Deferred tax assets and liabilities are measured using enacted tax rates expected to apply to taxable income in the years in which those temporary differences are anticipated to be recovered or settled. The effect on deferred tax assets and liabilities of a change in tax rates is recognized in the period that includes the enactment date. For regulatory and financial reporting purposes, investment tax credits (“ITC”) related to gas utility operations are deferred and amortized over the life of related fixed assets. As of December 31, 2022, the Company had cumulative book earnings of approximately $79 million in its foreign jurisdiction. Management previously asserted and continues to assert that all the earnings of Centuri’s Canadian subsidiaries will be permanently reinvested in Canada. As a result, no U.S. deferred income taxes have been recorded related to cumulative foreign earnings. The Financial Accounting Standards Board (the “FASB”) issued guidance to allow an accounting policy election of either (i) treating taxes attributable to future taxable income related to Global Intangible Low-Taxed Income (“GILTI”) as a current period expense when incurred or (ii) recognizing deferred taxes for temporary differences expected to reverse as GILTI in future years. The Company has elected to treat GILTI as a current period cost when incurred and has considered the estimated 2022 GILTI impact to its 2022 tax expense, which was immaterial.
Deferred Purchased Gas Costs	Deferred Purchased Gas Costs. The various regulatory commissions have established procedures to enable the rate-regulated companies to adjust billing rates for changes in the cost of natural gas purchased. The difference between the current cost of gas purchased and the cost of gas recovered in billed rates is deferred. Generally, these deferred amounts are recovered or refunded within one year.
Prepaid and other current assets	Prepaid and other current assets. Prepaid and other current assets for Southwest and the Company include, among other things, accrued purchased gas costs of $207 million in 2022 and $52 million in 2021. Additionally, Southwest had gas pipe materials and operating supplies of $77.3 million in 2022 and $62.9 million in 2021 (carried at weighted average cost). MountainWest’s materials and supplies were immaterial in the 2021 period in which they were included in the balance of Prepaid and other current assets in regard to the Company.
Held for sale	Held for sale. The Company and Southwest recognize the assets and liabilities of a disposal group as held for sale in the period (i) it has approved and committed to a plan to sell the disposal group, (ii) the disposal group is available for immediate sale in its present condition, (iii) an active program to locate a buyer and other actions to sell the disposal group have been initiated, (iv) it is unlikely that significant changes to the plan will be made or that the plan will be withdrawn. The Company and Southwest initially measure a disposal group that is classified as held for sale at the lower of its carrying value or fair value less any costs to sell. Any loss resulting from this measurement is recognized in the period in which the held for sale criteria are met. Conversely, gains are not recognized on the sale of a disposal group until closing. Upon designation as held for sale, the Company and Southwest stop recording depreciation expense and assess the fair value of the disposal group less any costs to sell at each reporting period, until it is no longer classified as held for sale.
Goodwill	Goodwill. As required by U.S. GAAP, goodwill is assessed for impairment annually, or more frequently, if circumstances indicate impairment to the carrying value of goodwill may have occurred. The goodwill impairment analysis was conducted as of October 1st using a qualitative assessment, as permitted by U.S. GAAP. Management of the Company and Southwest considered its reporting units and segments, determining that they remained consistent between periods presented below, and that no change was necessary with regard to the level at which goodwill is assessed for impairment. The acquisition of MountainWest resulted in a new reportable segment, which was assessed for impairment beginning in 2022, and upon being classified as held for sale, an impairment was recognized, as outlined below.
Other Current Liabilities	Other Current Liabilities. Management recognizes in its balance sheets various liabilities that are expected to be settled through future cash payment within the next twelve months, including certain regulatory mechanisms (refer to Note 5 - Regulatory Assets and Liabilities), customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities.
Accumulated Removal Costs	Accumulated Removal Costs. Approved regulatory practices allow Southwest to include in depreciation expense a component intended to recover removal costs associated with regulated operations plant retirements. In accordance with the Securities and Exchange Commission (“SEC”) position on presentation of these amounts, management reclassifies estimated removal costs from Accumulated depreciation to Accumulated removal costs within the liabilities section of the Consolidated Balance Sheets. Management regularly updates the estimated accumulated removal costs as amounts fluctuate between periods depending on the level of replacement work performed (and actual cost experience) compared to the estimated cost of removal in rates.
Gas Operating Revenues	Gas Operating Revenues. Southwest recognizes revenue when it satisfies its performance by transferring gas to the customer. Natural gas is delivered and “consumed” by the customer simultaneously. Revenues are recorded when customers are billed. Customer billings are substantially based on monthly meter reads and include certain other charges assessed monthly, and are calculated in accordance with applicable tariffs and state and local laws, regulations, and related agreements. An estimate of the margin associated with natural gas service provided, but not yet billed, to residential and commercial customers from the latest meter read date to the end of the reporting period is also recognized as accrued utility revenue. Revenues also include the net impacts of margin tracker/decoupling accruals based on criteria in U.S. GAAP for rate-regulated entities associated with alternative revenue programs. All of Southwest’s service territories have decoupled rate structures, which are designed to eliminate the direct link between volumetric sales and revenue, thereby mitigating the impacts of unusual weather variability and conservation on margin. See Note 3 - Revenue for additional information and also a description of MountainWest’s revenues. Utility Infrastructure Services Revenues. The majority of Centuri contracts are performed under unit-price contracts. Generally, these contracts state prices per unit of installation. Typical installations are accomplished in a few weeks or less. Revenues are recorded as installations are completed. Revenues are recorded for long-term fixed-price contracts in a pattern that reflects the transfer of control of promised goods and services to the customer over time. The amount of revenue recognized on fixed-price contracts is based on costs expended to date relative to anticipated final contract costs. Changes in job performance, job conditions, and final contract settlements are factors that influence management’s assessment of total contract value and the total estimated costs to complete those contracts. Revisions in estimates of costs and earnings during the course of work are reflected in the accounting period in which the facts requiring revision become known. If a loss on a contract becomes known or is anticipated, the entire amount of the estimated ultimate loss is recognized at that time in the financial statements. Some unit-price contracts contain caps that if encroached, trigger revenue and loss recognition similar to a fixed-price contract model. See Note 3 - Revenue. Intercompany Transactions. Centuri recognizes revenues generated from contracts with Southwest (see Note 13 - Segment Information). The accounts receivable balance, revenues, and associated profits are included in the consolidated financial statements of the Company and Southwest and are not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities. Utility Infrastructure Services Expenses. Centuri’s utility infrastructure services expenses in the Consolidated Statements of Income includes payroll expenses, office and equipment rental costs, subcontractor expenses, training, job-related materials, gains and losses on equipment sales, and professional fees. Net Cost of Gas Sold. Components of net cost of gas sold include natural gas commodity costs (fixed-price and variable-rate), pipeline capacity/transportation costs, and any actual settled costs of natural gas derivative instruments, where relevant. Also included are the net impacts of PGA deferrals and recoveries, which by their inclusion, result in net cost of gas sold overall that is comparable to amounts included in billed gas operating revenues. Differences between amounts incurred with suppliers, transmission pipelines, etc. and amounts already included in customer rates, are temporarily deferred in PGA accounts pending inclusion in customer rates.
Operations and Maintenance Expense	Operations and Maintenance Expense. Operations and maintenance expense includes Southwest’s operating and maintenance costs associated with serving utility customers and maintaining its distribution and transmission systems, uncollectible customer accounts expense, administrative and general salaries and expense, employee benefits expense excluding relevant non-service cost components, legal expense (including injuries and damages), professional and other external contracted services, and other business expenses. Also included are similar costs for MountainWest.
Depreciation and Amortization	Depreciation and Amortization. Regulated operations plant depreciation is computed on the straight-line remaining life method at composite rates considered sufficient to amortize costs over estimated service lives, including components which compensate for removal costs (net of salvage value), and retirements, as approved by the appropriate regulatory agency. When plant is retired from service, the original cost of plant, including cost of removal, less salvage, is charged to the accumulated provision for depreciation. See also discussion regarding Accumulated Removal Costs above. Other regulatory assets, including acquisition adjustments, are amortized when appropriate, over time periods authorized by regulators. Non-regulated operations, including utility infrastructure services-related property and equipment, are depreciated on a straight-line method based on the estimated useful lives of the related assets. Costs and gains related to refunding regulated operations debt and debt issuance expenses are deferred and amortized over the weighted-average lives of the new issues and become a component of interest expense.
Allowance for Funds Used During Construction ("AFUDC")	Allowance for Funds Used During Construction (“AFUDC”). AFUDC represents the cost of both debt and equity funds used to finance regulated operations plant construction. AFUDC is capitalized as part of the cost of regulated operations plant. The debt portion of AFUDC is reported in the Company’s and Southwest’s Consolidated Statements of Income as an offset to Net interest deductions and the equity portion is reported as Other income.
Derivatives	Derivatives. In managing its natural gas supply portfolios, Southwest has historically entered into fixed- and variable-price contracts, which qualify as derivatives. The fixed-price contracts, firm commitments to purchase a fixed amount of gas in the future at a fixed price, qualify for the normal purchases and normal sales exception that is allowed for contracts that are probable of delivery in the normal course of business, and are exempt from fair value reporting. The variable-price contracts qualify as derivative instruments; however, because the contract price is the prevailing price at the future transaction date, no fair value adjustment is required. Southwest does not utilize derivative financial instruments for speculative purposes, nor does it have trading operations.
Foreign Currency Translation and Transactions	Foreign Currency Translation and Transactions. Foreign currency-denominated assets and liabilities of consolidated subsidiaries are translated into U.S. dollars at exchange rates existing at the respective balance sheet dates. Translation adjustments resulting from fluctuations in exchange rates are recorded as a separate component of accumulated other comprehensive income within stockholders’ equity. Results of operations of foreign subsidiaries are translated using the monthly weighted-average exchange rates during the respective periods. Gains and losses resulting from foreign currency transactions are included in Other income and (expenses) of the Company. Gains and losses resulting from intercompany foreign currency transactions that are of a long-term investment nature are reported in Other comprehensive income, if applicable.
Earnings (Loss) Per Share	Earnings (Loss) Per Share. Basic earnings (loss) per share (“EPS”) in each period of this report were calculated by dividing net income (loss) attributable to Southwest Gas Holdings, Inc. by the weighted-average number of shares during those periods. Diluted EPS includes additional weighted-average common stock equivalents (performance shares and restricted stock units), if dilutive. Unless otherwise noted, the term “Earnings Per Share” refers to Basic EPS.
Recent Accounting Standards Updates	Recent Accounting Standards Updates. Accounting pronouncements effective or adopted in 2022: In March 2020, the FASB issued Accounting Standards Update (“ASU”) 2020-04 “Reference Rate Reform (Topic 848): Facilitation of the Effects of Reference Rate Reform on Financial Reporting.” The update provides optional guidance for a limited time to ease the potential burden in accounting for, or recognizing the effects of, reference rate reform on financial reporting, including when modifying a contract (during the eligibility period covered by the update to the topic) to replace a reference rate affected by reference rate reform. The update applies only to contracts and hedging relationships that reference the London Interbank Offered Rate (“LIBOR”) or another reference rate expected to be discontinued due to reference rate reform. The guidance was eligible to be applied upon issuance on March 12, 2020, and can generally be applied through December 31, 2022. In December 2022, the FASB issued ASU 2022-06 “Reference Rate Reform (Topic 848): Deferral of the Sunset Date of Topic 848.” The update provides deferral of the sunset date of Topic 848 from December 31, 2022 to December 31, 2024. Management will continue to monitor the impacts this update might have on the Company’s and Southwest’s consolidated financial statements and disclosures, and will reflect such appropriately, in the event that the optional guidance is elected. See also LIBOR discussion in Note 8 - Debt. In August 2020, the FASB issued ASU 2020-06 “Debt—Debt with Conversion and Other Options (Subtopic 470-20) and Derivatives and Hedging— Contracts in Entity’s Own Equity (Subtopic 815-40): Accounting for Convertible Instruments and Contracts in an Entity’s Own Equity.” The update, amongst other amendments, improves the guidance related to the disclosures and earnings per share for convertible instruments and contracts in an entity’s own equity. The Company and Southwest adopted the update in the first quarter of 2022, the impact of which was not material to the consolidated financial statements of the Company or Southwest. There are no other recently issued accounting standards updates that are expected to be adopted or material to Southwest or the Company effective in 2023 or thereafter.
Subsequent Events	Subsequent Events. Management monitors events occurring after the balance sheet date and prior to the issuance of the financial statements to determine the impacts, if any, of events on the financial statements to be issued or disclosures to be made, and has reflected them where appropriate.
Receivables and Related Allowances	Business activity with respect to natural gas utility operations is conducted with customers located within the three-state region of Arizona, Nevada, and California. Southwest’s accounts receivable are short-term in nature, with billing due dates customarily not extending beyond one month, with customers’ credit worthiness assessed upon account creation by evaluation of other utility service or their credit file, and related payment history. Although Southwest seeks generally to minimize its credit risk related to utility operations by requiring security deposits from new customers, imposing late fees, and actively pursuing collection on overdue accounts, some accounts are ultimately not collected. Customer accounts are subject to collection procedures that vary by jurisdiction (late fee assessment, notice requirements for disconnection of service, and procedures for actual disconnection and/or reestablishment of service). After disconnection of service, accounts are customarily written off approximately two months after disconnection if the account remains inactive. Dependent upon the jurisdiction, reestablishment of service requires both payment of previously unpaid balances and additional deposit requirements. Provisions for uncollectible accounts are recorded monthly based on experience, consideration of current and expected future conditions, customer and rate composition, and write-off processes. They are included in the ratemaking process as a cost of service. The Nevada jurisdictions have a regulatory mechanism associated with the gas-cost-related portion of uncollectible accounts. Such amounts are deferred and collected through a surcharge in the ratemaking process. Southwest lifted the moratorium on disconnection of natural gas service for non-payment in Arizona and Nevada in September 2021, which was initiated (at the same time as a moratorium on late fees) in March 2020 in response to the COVID-19 pandemic. The moratorium on disconnection in California ended in November 2021. Southwest recommenced assessing late fees on past-due balances in Arizona and Nevada in April 2021, and in California in August 2021. After these moratoriums were lifted, Southwest resumed collection efforts. These moratoriums have influenced our bad debt expense and write-offs through 2022. Southwest continues to actively work with customers experiencing financial hardship by means of flexible payment options and partnering with assistance agencies. Management continues to monitor expected credit losses in light of the impacts of events/conditions such as COVID-19, local/regional inflation, and others. In addition, management is monitoring the impact of certain residential disconnection protections recently established in Southwest’s California jurisdictions, such as prohibiting credit deposits and fees for reconnection, among other things. While a two-way balancing account was permitted to track residential uncollectible accounts for future recovery, the mechanism is subject to a cap, above which uncollectible expense would nonetheless be incurred and recognized. The allowance as of December 31, 2022 reflects the expected impact from the pandemic on balances as of that date, including consideration of customers’ current and future ability to pay those amounts that are due. Utility infrastructure services accounts receivable are recorded at face amounts less an allowance for doubtful accounts. Centuri’s customers are generally investment-grade gas and electric utility companies for which Centuri has historically recognized an insignificant amount of write-offs. Centuri’s accounts receivable balances carry standard payment terms of up to 60 days. Centuri maintains an allowance that is estimated based on historical collection experience, current and estimated future economic and market conditions, and a review of the current status of each customer's accounts receivable balance. Account balances are monitored at least monthly, and are charged off against the allowance when management determines it is probable the balance will not be recovered. Centuri has not been significantly impacted, nor does it anticipate it will experience significant difficulty in collecting amounts due, given the nature of its customers, as a result of the COVID-19 environment, historically high inflation, or other conditions.

Income Taxes (Tables)

12 Months Ended

Dec. 31, 2022

Income Tax Disclosure [Abstract]

Summary of Income (Loss) Before Taxes and Noncontrolling Interest for Domestic and Foreign Operations

The following is a summary of income (loss) before taxes and noncontrolling interests for domestic and foreign operations:


	Year ended December 31,
(Thousands of dollars)	2022		2021		2020
U.S.	$	(302,581)	$	221,507	$	282,489
Foreign	29,244		25,343		22,249
Total income (loss) before income taxes	$	(273,337)	$	246,850	$	304,738

Summary of Income Tax Expense (Benefit)

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Current:
Federal	$	(949)	$	(2,872)	$	6,287
State	7,123		(11,516)		8,617
Foreign	9,089		6,524		4,666
	15,263		(7,864)		19,570
Deferred:
Federal	(76,984)		39,117		44,547
State	(12,828)		8,239		414
Foreign	(1,104)		156		1,222
	(90,916)		47,512		46,183
Total income tax expense (benefit)	$	(75,653)	$	39,648	$	65,753

Income tax expense (benefit) consists of the following:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Current:
Federal	$	(78)	$	(3,643)	$	(4,678)
State	7,805		(6,556)		(179)
	7,727		(10,199)		(4,857)
Deferred:
Federal	23,710		36,842		38,561
State	(896)		2,695		2,051
	22,814		39,537		40,612
Total income tax expense	$	30,541	$	29,338	$	35,755

Significant Components of Deferred Income Tax Expense (Benefit)

Deferred income tax expense (benefit) consists of the following significant components:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Deferred federal and state:
Property-related items	$	41,191	$	35,072	$	50,504
Purchased gas cost adjustments	76,306		73,613		(5,726)
Employee benefits	12,223		(1,484)		459
Regulatory adjustments	(15,482)		(10,101)		(9,885)
Deferred payroll taxes	(6,344)		(6,344)		(9,055)
Deferred revenue	5,751		6,021		588
Net operating loss	(120,704)		(64,981)		2,331
Goodwill impairment	(105,507)		—		—
Alternative minimum tax	—		—		4,409
All other deferred	21,669		15,768		12,610
Total deferred federal and state	(90,897)		47,564		46,235
Deferred ITC, net	(19)		(52)		(52)
Total deferred income tax expense (benefit)	$	(90,916)	$	47,512	$	46,183

Deferred income tax expense (benefit) consists of the following significant components:


	Year Ended December 31,
(Thousands of dollars)	2022		2021		2020
Deferred federal and state:
Property-related items	$	29,633	$	23,077	$	36,029
Purchased gas cost adjustments	76,306		73,613		(5,726)
Employee benefits	5,332		5,508		11,437
Regulatory adjustments	(15,482)		(10,101)		(9,885)
Deferred payroll taxes	(892)		(892)		(1,810)
Alternative minimum tax	—		—		4,409
Net operating loss	(76,080)		(59,119)		—
All other deferred	4,016		7,503		6,210
Total deferred federal and state	22,833		39,589		40,664
Deferred ITC, net	(19)		(52)		(52)
Total deferred income tax expense	$	22,814	$	39,537	$	40,612

Reconciliation of U.S Federal Statutory Rate to Consolidated Effective Tax Rate

A reconciliation of the U.S. federal statutory rate to the consolidated effective tax rate (and the sources of these differences and the effect of each) are summarized as follows:


	Year Ended December 31,
	2022		2021		2020
U.S. federal statutory income tax rate	21.0	%	21.0	%	21.0	%
Net state taxes	3.2		1.0		3.0
Tax credits	0.2		(0.5)		(0.5)
Company-owned life insurance	(0.8)		(1.1)		(0.8)

Amortization of excess deferred taxes	5.2		(4.3)		(0.8)

All other differences	(1.1)		—		(0.3)
Consolidated effective income tax rate	27.7	%	16.1	%	21.6	%

A reconciliation of the U.S. federal statutory rate to the consolidated effective tax rate (and the sources of these differences and the effect of each) are summarized as follows:


	Year Ended December 31,
	2022		2021		2020
U.S. federal statutory income tax rate	21.0	%	21.0	%	21.0	%
Net state taxes	1.6		0.3		1.7
Tax credits	(0.3)		(0.6)		(0.7)
Company-owned life insurance	0.6		(0.9)		(1.0)

Amortization of excess deferred taxes	(6.9)		(4.9)		(1.3)
All other differences	0.5		(1.3)		(1.4)
Effective income tax rate	16.5	%	13.6	%	18.3	%

Deferred Tax Assets and Liabilities

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2022		2021
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	109,093	$	116,496
Employee benefits	29,307		39,181

Net operating losses	223,557		102,853
Deferred payroll taxes	—		6,344
Lease-related item	19,745		18,462
Goodwill impairment	105,507		—
Other	13,197		12,149
Valuation allowance	(2,197)		(4,902)
	498,209		290,583
Deferred tax liabilities:
Property-related items, including accelerated depreciation	873,328		843,559
Regulatory balancing accounts	154,124		77,818

Debt-related costs	(2,365)		2,277
Intangibles	105,668		97,860
Lease-related item	21,164		17,254
Other	28,275		20,562
	1,180,194		1,059,330
Net noncurrent deferred tax liabilities	$	681,985	$	768,747

Deferred tax assets and liabilities consist of the following:


	December 31,
(Thousands of dollars)	2022		2021
Deferred tax assets:
Deferred income taxes for future amortization of ITC and excess deferred taxes	$	94,273	$	101,133
Employee benefits	(12,604)		(4,671)
Net operating losses	135,200		59,119
Deferred payroll taxes	—		892
Other	2,512		6,777
Valuation allowance	—		(22)
	219,381		163,228
Deferred tax liabilities:
Property-related items, including accelerated depreciation	733,011		703,374
Regulatory balancing accounts	154,124		77,818

Debt-related costs	2,062		2,277
Other	14,132		18,587
	903,329		802,056
Net deferred tax liabilities	$	683,948	$	638,828

Reconciliation of Unrecognized Tax Benefits

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2022		2021
Unrecognized tax benefits at beginning of year	$	2,629	$	1,928
Gross increases – tax positions in prior period	389		442

Gross increases – current period tax positions	54		259
Gross decreases – current period tax positions	—		—
Settlements	—		—
Lapse in statute of limitations	—		—
Unrecognized tax benefits at end of year	$	3,072	$	2,629

A reconciliation of the beginning and ending amount of unrecognized tax benefits is as follows:


	December 31,
(Thousands of dollars)	2022		2021
Unrecognized tax benefits at beginning of year	$	2,362	$	1,793
Gross increases – tax positions in prior period	259		310
Gross decreases – tax positions in prior period	—		—
Gross increases – current period tax positions	23		259
Gross decreases – current period tax positions	—		—
Settlements	—		—
Lapse in statute of limitations	—		—
Unrecognized tax benefits at end of year	$	2,644	$	2,362

Summary of Income Before Taxes for Continuing and Discontinued Operations

The following is a summary of income before taxes:


	Year ended December 31,
(Thousands of dollars)	2022		2021		2020
Total income before income taxes	$	184,921	$	216,473	$	194,873

Regulated Operations Plant and Leases - Narrative (Details) - USD ($) $ in Millions	12 Months Ended			36 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2022
Public Utility, Property, Plant and Equipment [Line Items]
Annual utility depreciation and amortization expense percentage	2.70%	2.70%	2.70%
Amortization of intangibles	$ 29.8	$ 17.3	$ 10.8
Short-term lease, terms less than one month, cost			66.4
Centuri
Public Utility, Property, Plant and Equipment [Line Items]
Lease remaining lease term (up to)	16 years			16 years
Lease renewal term (up to)	5 years			5 years
Lease termination period	1 year
Gas plant
Public Utility, Property, Plant and Equipment [Line Items]
Amortization of intangibles	$ 21.0	$ 17.7	$ 13.7
Gas, Transmission and Distribution Plant
Public Utility, Property, Plant and Equipment [Line Items]
Annual utility depreciation and amortization expense percentage				2.20%

CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Common stock shares	Additional paid-in capital	Accumulated other comprehensive loss	Retained earnings	Southwest Gas Holdings, Inc.
Beginning balance (in shares) at Dec. 31, 2019		55,007,000
Beginning balance at Dec. 31, 2019		$ 56,637	$ 1,466,937	$ (56,732)	$ 1,039,072
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuances (in shares)		2,186,000
Common stock issuances		$ 2,186	142,218
Foreign currency exchange translation adjustment				1,713
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax				(8,451)
FSIRS amounts reclassified to net income, net of tax	$ 2,467			2,467
Net income (loss)					232,324
Redemption value adjustments					(74,513)
Dividends declared					(128,905)
Ending balance (in shares) at Dec. 31, 2020		57,193,000
Ending balance at Dec. 31, 2020		$ 58,823	1,609,155	(61,003)	1,067,978	$ 2,674,953
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in USD per share)	$ 2,280
Common stock issuances (in shares)		3,229,000
Common stock issuances		$ 3,229	219,298
Promissory notes in association with redeemable noncontrolling interest			(4,237)
Foreign currency exchange translation adjustment				20
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax				12,570
FSIRS amounts reclassified to net income, net of tax	$ 1,652			1,652
Net income (loss)					200,779
Redemption value adjustments	$ 12,016				(12,016)
Dividends declared					(142,428)
Ending balance (in shares) at Dec. 31, 2021	60,422,081	60,422,000
Ending balance at Dec. 31, 2021		$ 62,052	1,824,216	(46,761)	1,114,313	2,953,820
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in USD per share)	$ 2,380
Common stock issuances (in shares)		6,697,000
Common stock issuances		$ 6,697	462,967
Foreign currency exchange translation adjustment				(6,133)
Net actuarial gain (loss) arising during period, less amortization of unamortized benefit plan cost, net of tax				8,236
FSIRS amounts reclassified to net income, net of tax	$ 416			416
Net income (loss)					(203,290)
Redemption value adjustments	$ (3,325)				3,325
Dividends declared					(167,279)
Ending balance (in shares) at Dec. 31, 2022	67,119,143	67,119,000
Ending balance at Dec. 31, 2022		$ 68,749	$ 2,287,183	$ (44,242)	$ 747,069	$ 3,058,759
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per common share (in USD per share)	$ 2,480

Pension and Other Postretirement Benefits - Schedule of Accumulated Benefit Obligation (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Retirement plan
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 1,074,493	$ 1,395,773
SERP
Defined Benefit Plan Disclosure [Line Items]
Accumulated benefit obligation	$ 39,263	$ 46,885

Income Taxes - Significant Components of Deferred Income Tax Expense (Benefit) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Deferred federal and state:
Total deferred federal and state	$ (90,897)	$ 47,564	$ 46,235
Deferred ITC, net	(19)	(52)	(52)
Total deferred income tax expense (benefit)	(90,916)	47,512	46,183
Property-related items
Deferred federal and state:
Total deferred federal and state	41,191	35,072	50,504
Purchased gas cost adjustments
Deferred federal and state:
Total deferred federal and state	76,306	73,613	(5,726)
Employee benefits
Deferred federal and state:
Total deferred federal and state	12,223	(1,484)	459
Regulatory adjustments
Deferred federal and state:
Total deferred federal and state	(15,482)	(10,101)	(9,885)
Deferred payroll taxes
Deferred federal and state:
Total deferred federal and state	(6,344)	(6,344)	(9,055)
Deferred revenue
Deferred federal and state:
Total deferred federal and state	5,751	6,021	588
Net operating loss
Deferred federal and state:
Total deferred federal and state	(120,704)	(64,981)	2,331
Goodwill impairment
Deferred federal and state:
Total deferred federal and state	(105,507)	0	0
Alternative minimum tax
Deferred federal and state:
Total deferred federal and state	0	0	4,409
All other deferred
Deferred federal and state:
Total deferred federal and state	21,669	15,768	12,610
Southwest Gas Corporation
Deferred federal and state:
Total deferred federal and state	22,833	39,589	40,664
Deferred ITC, net	(19)	(52)	(52)
Total deferred income tax expense (benefit)	22,814	39,537	40,612
Southwest Gas Corporation \| Property-related items
Deferred federal and state:
Total deferred federal and state	29,633	23,077	36,029
Southwest Gas Corporation \| Purchased gas cost adjustments
Deferred federal and state:
Total deferred federal and state	76,306	73,613	(5,726)
Southwest Gas Corporation \| Employee benefits
Deferred federal and state:
Total deferred federal and state	5,332	5,508	11,437
Southwest Gas Corporation \| Regulatory adjustments
Deferred federal and state:
Total deferred federal and state	(15,482)	(10,101)	(9,885)
Southwest Gas Corporation \| Deferred payroll taxes
Deferred federal and state:
Total deferred federal and state	(892)	(892)	(1,810)
Southwest Gas Corporation \| Net operating loss
Deferred federal and state:
Total deferred federal and state	(76,080)	(59,119)	0
Southwest Gas Corporation \| Alternative minimum tax
Deferred federal and state:
Total deferred federal and state	0	0	4,409
Southwest Gas Corporation \| All other deferred
Deferred federal and state:
Total deferred federal and state	$ 4,016	$ 7,503	$ 6,210

Regulatory Assets and Liabilities - Schedule of Components of Other Regulatory Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Regulatory Assets [Line Items]
Regulatory assets	$ 1,088,178	$ 831,610
Southwest Gas Corporation
Regulatory Assets [Line Items]
Regulatory assets		798,897
State mandated public purpose programs (including low income and conservation programs)
Regulatory Assets [Line Items]
Regulatory assets	18,693	15,239
State mandated public purpose programs (including low income and conservation programs) \| Southwest Gas Corporation
Regulatory Assets [Line Items]
Regulatory assets		15,239
Infrastructure replacement programs and similar
Regulatory Assets [Line Items]
Regulatory assets	8,533	6,545
Infrastructure replacement programs and similar \| Prepaids and other current assets
Regulatory Assets [Line Items]
Regulatory assets	930
Infrastructure replacement programs and similar \| Southwest Gas Corporation
Regulatory Assets [Line Items]
Regulatory assets		6,545
Environmental compliance programs
Regulatory Assets [Line Items]
Regulatory assets	5,803	6,807
Environmental compliance programs \| Prepaids and other current assets
Regulatory Assets [Line Items]
Regulatory assets	5,000	5,800
Environmental compliance programs \| Deferred charges and other assets
Regulatory Assets [Line Items]
Regulatory assets	825	1,000
Environmental compliance programs \| Southwest Gas Corporation
Regulatory Assets [Line Items]
Regulatory assets		6,807
Pension tracking mechanism
Regulatory Assets [Line Items]
Regulatory assets	13,098	10,281
Pension tracking mechanism \| Southwest Gas Corporation
Regulatory Assets [Line Items]
Regulatory assets		10,281
Other Miscellaneous Regulatory Asset
Regulatory Assets [Line Items]
Regulatory assets	19,854	23,361
Other Miscellaneous Regulatory Asset \| Prepaids and other current assets
Regulatory Assets [Line Items]
Regulatory assets	6,400	7,700
Other Miscellaneous Regulatory Asset \| Deferred charges and other assets
Regulatory Assets [Line Items]
Regulatory assets	13,400	15,600
Other Miscellaneous Regulatory Asset \| Southwest Gas Corporation
Regulatory Assets [Line Items]
Regulatory assets		21,926
Other Miscellaneous Regulatory Asset \| Southwest Gas Corporation \| Prepaids and other current assets
Regulatory Assets [Line Items]
Regulatory assets		6,700
Other Miscellaneous Regulatory Asset \| Southwest Gas Corporation \| Deferred charges and other assets
Regulatory Assets [Line Items]
Regulatory assets		15,200
Other
Regulatory Assets [Line Items]
Regulatory assets	$ 65,981	62,233
Other \| Southwest Gas Corporation
Regulatory Assets [Line Items]
Regulatory assets		$ 60,798

Segment Information - Accounts Receivable for Services (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Centuri
Segment Reporting Information [Line Items]
Accounts receivable for Centuri services	$ 18,067	$ 15,166

- Definition

The aggregate amount of receivables to be collected from related parties where one party can exercise control or significant influence over another party; including affiliates, owners or officers and their immediate families, pension trusts, and so forth, at the financial statement date. which are usually due within one year (or one business cycle).

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iii)(C))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442552-122756

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section 45
-Paragraph 1
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=124098289&loc=d3e6676-107765

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(4)(iv))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442552-122756

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iv))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442526-122756

Reference 5: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1B
-Subparagraph (SX 210.13-02(a)(5))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442552-122756

Reference 6: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(4)(iii)(B))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442526-122756

Reference 7: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 850
-SubTopic 10
-Section 50
-Paragraph 1
-Subparagraph (d)
-URI https://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864

Reference 8: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(3)(a)(2))
-URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682

Reference 9: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 10
-Section S99
-Paragraph 1A
-Subparagraph (SX 210.13-01(a)(5))
-URI https://asc.fasb.org/extlink&oid=126975872&loc=SL124442526-122756

Reference 10: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08(k)(1))
-URI https://asc.fasb.org/extlink&oid=120395691&loc=d3e23780-122690

+ Details

Income Taxes - Summary of Income Before Taxes for Continuing and Discontinued Operations (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Southwest Gas Corporation
Segment Reporting, Reconciling Item for Operating Profit (Loss) from Segment to Consolidated [Line Items]
Total income before income taxes	$ 184,921	$ 216,473	$ 194,873

Acquisitions and Dispositions

12 Months Ended

Dec. 31, 2022

Business Combination and Dispositions [Abstract]

Acquisitions and Dispositions

Note 15 - Acquisitions and Dispositions

Acquisitions

In August 2021, the Company, through its subsidiaries, led principally by Centuri, completed the acquisition of Drum, including its primary subsidiary, Riggs Distler. Additionally, in December 2021, the Company completed the acquisition of the MountainWest entities. During the year ended December 31, 2022, MountainWest recorded measurement period adjustments of $28.2 million, primarily due to a final post-closing payment; as a result, goodwill was reduced by that amount. The purchase accounting for both acquisitions was finalized in 2022. The following unaudited pro forma financial information reflects the consolidated results of operations of the Company assuming the Riggs Distler and MountainWest acquisitions had taken place on January 1, 2020. The most significant pro forma adjustments relate to: (i) reflecting approximately $48.7 million in transaction costs in the year ended December 31, 2020, and excluding such costs from the year ended December 31, 2021, and (ii) reflecting incremental interest expense of $48.4 million in 2021, and approximately $52.1 million in the comparable 2020 period. The pro forma financial information has been prepared for comparative purposes only, and is not intended to be indicative of what the Company’s results would have been had the acquisition occurred at the beginning of the periods presented or of what results may be in the future, for a number of reasons. The reasons include, but are not limited to, differences between the assumptions used to prepare the pro forma information, potential cost savings from operating efficiencies, nor the impact of incremental costs incurred in integrating the businesses.

Amounts below are in millions of dollars, except per share amounts.


	Unaudited
	Year Ended December 31,
	2021		2020
Total operating revenues	$	4,236	$	3,980
Net income attributable to Southwest Gas Holdings, Inc.	$	278	$	276
Basic earnings per share	$	4.70	$	4.93
Diluted earnings per share	$	4.69	$	4.93

Dispositions

In December 2022, the Company announced that the Board unanimously determined to take strategic actions to simplify the Company’s portfolio of businesses. These actions included entering into a definitive agreement to sell 100% of MountainWest in an all-cash transaction to Williams for $1.5 billion in total enterprise value, subject to certain adjustments. Additionally, the Company determined it will pursue a spin-off of Centuri to form a new independent publicly traded utility infrastructure services company. The MountainWest transaction closed on February 14, 2023. Upon close, the Company is expected to provide certain services to Williams under a transition services agreement for a brief period, generally not beyond six months. The Centuri spin-off is expected to be completed in the fourth quarter of 2023 or the first quarter of 2024 and to be tax free to the Company and its stockholders for U.S. federal income tax purposes. The separation will be subject to, among other things,

finalizing the transaction structure, final approval by the Board, approval by the ACC, the receipt of a favorable IRS private letter ruling relating to the tax-free nature of the transaction, and the effectiveness of a registration statement that will be filed with the SEC.

As a result of entering into a definitive agreement to sell MountainWest and considering other factors, the Company determined that MountainWest met criteria to be characterized as held for sale as of December 31, 2022, and as a result, MountainWest’s assets and liabilities, excluding income tax related balances, have been presented as held for sale on the Company’s consolidated balance sheet. The MountainWest sale did not meet the criteria for reporting discontinued operations as the sale did not represent a strategic shift that would have a major effect on the Company’s operations or financial results. Company management considered the estimated proceeds, which were below the carrying value of the disposal group, and determined that the loss on disposal was attributable to goodwill, resulting in an impairment loss of $449.6 million. The goodwill impairment loss is reported in Goodwill impairment and cost to sell on the Company’s Consolidated Statement of Income for the year ended December 31, 2022. The Company believes that the sale price of $1.5 billion, as adjusted for indebtedness and other estimated adjustments per the purchase and sale agreement, provided a reasonable indication of the fair value of MountainWest as it represents an exit price in an orderly transaction between market participants. While the fair value was estimated based on the closing statement from the sale of MountainWest, it is subject to certain adjustments, including a post-closing payment related to final working capital balances. The amount of such post-closing payment is not determinable at this time. The Company estimated the working capital balances as of February 14, 2023; however, these amounts are subject to change and could result in additional losses in the second quarter of 2023 when working capital is finalized. The Company recorded an additional loss of approximately $5.8 million, attributable to estimated selling costs, which is also included in Goodwill impairment and cost to sell on the Company’s Consolidated Statement of Income for the year ended December 31, 2022.

The carrying amounts of major classes of assets and liabilities relating to MountainWest, all of which are classified as current and reported as held for sale in the Company’s Consolidated Balance Sheets, are as follows:


(Thousands of dollars)
Regulated operations plant, net of accumulated depreciation of $907 million	$	957,729
Other property and investments	49,546
Other current assets (1)	188,629
Goodwill, net of accumulated impairment of $449.6 million	508,395
Deferred charges and other assets (2)	39,050
Total assets	1,743,349
Less: cost to sell	5,819
Total current assets, held for sale	$	1,737,530

Other current liabilities (3)	$	55,188
Long-term debt	448,862
Other deferred credits and liabilities (3)	140,195
Total current liabilities, held for sale	$	644,245

(1) Includes cash and cash equivalents of $23.8 million, regulatory assets of $2.2 million, and “in-kind” system gas imbalance of $116.6 million due to a significant increase in natural gas prices in December 2022.

(2) Includes regulatory assets of $30.1 million.

(3) Includes $18.9 million of regulatory liabilities included in Other current liabilities, and $139 million of regulatory liabilities included in Other deferred credits and liabilities (including $60.2 million related to regulatory excess deferred/other taxes and gross-up and $58.8 million of accumulated removal costs).

The pretax loss for MountainWest for the year ended December 31, 2022 was $373 million, due to the goodwill impairment recognized.

On September 22, 2022, the FERC issued an order initiating an investigation, pursuant to section 5 of the Natural Gas Act, to determine whether rates currently charged by MountainWest Overthrust Pipeline, LLC, a subsidiary of MountainWest, are just and reasonable and setting the matter for hearing (the “Section 5 Rate Case”). Unless earlier settled by the parties, a hearing on the matter is to commence on August 1, 2023 with an initial decision from the presiding administrative law judge due by November 14, 2023. Under the terms of the MountainWest Purchase Agreement, the Company is obligated, for a period of four

years following the closing of the sale of MountainWest, to indemnify Williams and MountainWest for any damages and liabilities resulting from the Section 5 Rate Case, including any reduction to the current applicable rate, up to a cap of $75 million. Williams has agreed that it will not enter into any settlement of the Section 5 Rate Case that will result in any damages being paid by the Company under such indemnity without the prior written consent of the Company (which consent shall not be unreasonably withheld). The range of loss, if any, that could result from this matter cannot currently be estimated.

Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Mar. 31, 2022	Dec. 31, 2021
Debt Instrument [Line Items]
Total	$ 726,412
Less: current maturities	(44,557)		$ (297,324)
Long-term debt, less current maturities	4,403,299		4,115,684
Southwest Gas Corporation
Debt Instrument [Line Items]
Total	457,500
Less: current maturities	0		(275,000)
Long-term debt, less current maturities	3,251,296		$ 2,440,603
Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Total	$ 407,500
Debentures \| Notes, 6.1%, due 2041 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	6.10%
Debentures \| Notes, 4.05%, due 2032 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	4.05%	4.05%
Debentures \| Notes, 3.875%, due 2022 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate		3.875%	3.875%
Debentures \| Notes, 4.875%, due 2043 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	4.875%
Debentures \| Notes, 3.8%, due 2046 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	3.80%
Debentures \| Notes, 3.7%, due 2028 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	3.70%
Debentures \| Notes, 4.15%, due 2049 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	4.15%
Debentures \| Notes, 2.2%, due 2030 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	2.20%
Debentures \| Notes, 3.18%, due 2051 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	3.18%
Debentures \| Notes, 5.8%, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	5.80%
Debentures \| 8% Series, due 2026 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	8.00%
Debentures \| Medium-term notes, 7.78% series, due 2022 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate			7.78%
Debentures \| Medium-term notes, 7.92% series, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	7.92%
Debentures \| Medium-term notes, 6.76% series, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	6.76%
Revolving credit facility and commercial paper \| Southwest Gas Corporation
Debt Instrument [Line Items]
Total	$ 50,000
Secured Debt \| Centuri secured revolving credit facility
Debt Instrument [Line Items]
Total	81,955
Secured Debt \| Centuri secured term loan facility
Debt Instrument [Line Items]
Total	60,113
Unsecured Debt \| MountainWest unsecured senior notes, 3.53%, due in 2028
Debt Instrument [Line Items]
Debt instrument interest rate			3.53%
Unsecured Debt \| MountainWest unsecured senior notes, 4.875%, due in 2041
Debt Instrument [Line Items]
Debt instrument interest rate			4.875%
Unsecured Debt \| MountainWest unsecured senior notes, 3.91%, due in 2038
Debt Instrument [Line Items]
Debt instrument interest rate			3.91%
Other debt obligations
Debt Instrument [Line Items]
Total	126,844
Carrying Amount
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(20,789)		$ (24,466)
Less: current maturities	(44,557)		(22,324)
Long-term debt, less current maturities	4,403,299		4,115,684
Carrying Amount \| Southwest Gas Corporation
Debt Instrument [Line Items]
Less: current maturities	0		(275,000)
Long-term debt, less current maturities	3,251,296		2,440,603
Carrying Amount \| Debentures \| Southwest Gas Corporation
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(29,471)		(19,959)
Total	3,003,029		2,387,541
Carrying Amount \| Debentures \| Notes, 6.1%, due 2041 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	125,000		125,000
Carrying Amount \| Debentures \| Notes, 4.05%, due 2032 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	600,000		0
Carrying Amount \| Debentures \| Notes, 3.875%, due 2022 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	0		250,000
Carrying Amount \| Debentures \| Notes, 4.875%, due 2043 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	250,000		250,000
Carrying Amount \| Debentures \| Notes, 3.8%, due 2046 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 3.7%, due 2028 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 4.15%, due 2049 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 2.2%, due 2030 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	450,000		450,000
Carrying Amount \| Debentures \| Notes, 3.18%, due 2051 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	300,000		300,000
Carrying Amount \| Debentures \| Notes, 5.8%, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	300,000		0
Carrying Amount \| Debentures \| 8% Series, due 2026 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	75,000		75,000
Carrying Amount \| Debentures \| Medium-term notes, 7.78% series, due 2022 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	0		25,000
Carrying Amount \| Debentures \| Medium-term notes, 7.92% series, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	25,000		25,000
Carrying Amount \| Debentures \| Medium-term notes, 6.76% series, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	7,500		7,500
Carrying Amount \| Revolving credit facility and commercial paper \| Southwest Gas Corporation
Debt Instrument [Line Items]
Total	50,000		130,000
Carrying Amount \| Industrial development revenue bonds \| Southwest Gas Corporation
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(1,733)		(1,938)
Total	198,267		198,062
Carrying Amount \| Industrial development revenue bonds \| Tax-exempt Series A, due 2028 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Carrying Amount \| Industrial development revenue bonds \| 2003 Series A, due 2038 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Carrying Amount \| Industrial development revenue bonds \| 2008 Series A, due 2038 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Carrying Amount \| Industrial development revenue bonds \| 2009 Series A, due 2039 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Carrying Amount \| Secured Debt \| Centuri \| Centuri secured revolving credit facility
Debt Instrument [Line Items]
Long-term debt, gross	81,955		103,329
Carrying Amount \| Secured Debt \| Centuri secured term loan facility \| Centuri
Debt Instrument [Line Items]
Long-term debt, gross	1,008,550		1,117,138
Carrying Amount \| Unsecured Debt \| MountainWest unsecured senior notes, 3.53%, due in 2028
Debt Instrument [Line Items]
Long-term debt, gross	0		102,078
Carrying Amount \| Unsecured Debt \| MountainWest unsecured senior notes, 4.875%, due in 2041
Debt Instrument [Line Items]
Long-term debt, gross	0		199,926
Carrying Amount \| Unsecured Debt \| MountainWest unsecured senior notes, 3.91%, due in 2038
Debt Instrument [Line Items]
Long-term debt, gross	0		147,735
Carrying Amount \| Other debt obligations
Debt Instrument [Line Items]
Long-term debt, gross	126,844		51,665
Fair Value \| Debentures \| Notes, 6.1%, due 2041 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	113,184		166,380
Fair Value \| Debentures \| Notes, 4.05%, due 2032 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	527,052		0
Fair Value \| Debentures \| Notes, 3.875%, due 2022 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	0		250,603
Fair Value \| Debentures \| Notes, 4.875%, due 2043 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	195,703		307,538
Fair Value \| Debentures \| Notes, 3.8%, due 2046 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	209,169		329,055
Fair Value \| Debentures \| Notes, 3.7%, due 2028 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	275,043		325,191
Fair Value \| Debentures \| Notes, 4.15%, due 2049 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	218,712		342,030
Fair Value \| Debentures \| Notes, 2.2%, due 2030 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	353,763		440,838
Fair Value \| Debentures \| Notes, 3.18%, due 2051 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	185,523		292,116
Fair Value \| Debentures \| Notes, 5.8%, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	305,913		0
Fair Value \| Debentures \| 8% Series, due 2026 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	80,027		92,623
Fair Value \| Debentures \| Medium-term notes, 7.78% series, due 2022 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	0		25,122
Fair Value \| Debentures \| Medium-term notes, 7.92% series, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	26,840		31,555
Fair Value \| Debentures \| Medium-term notes, 6.76% series, due 2027 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	7,662		8,949
Fair Value \| Revolving credit facility and commercial paper \| Southwest Gas Corporation
Debt Instrument [Line Items]
Total	50,000		130,000
Fair Value \| Industrial development revenue bonds \| Tax-exempt Series A, due 2028 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Industrial development revenue bonds \| 2003 Series A, due 2038 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Industrial development revenue bonds \| 2008 Series A, due 2038 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Industrial development revenue bonds \| 2009 Series A, due 2039 \| Southwest Gas Corporation
Debt Instrument [Line Items]
Long-term debt, gross	50,000		50,000
Fair Value \| Secured Debt \| Centuri \| Centuri secured revolving credit facility
Debt Instrument [Line Items]
Long-term debt, gross	82,315		103,749
Fair Value \| Secured Debt \| Centuri secured term loan facility \| Centuri
Debt Instrument [Line Items]
Long-term debt, gross	995,852		1,117,841
Fair Value \| Unsecured Debt \| MountainWest unsecured senior notes, 3.53%, due in 2028
Debt Instrument [Line Items]
Long-term debt, gross	0		102,078
Fair Value \| Unsecured Debt \| MountainWest unsecured senior notes, 4.875%, due in 2041
Debt Instrument [Line Items]
Long-term debt, gross	0		199,926
Fair Value \| Unsecured Debt \| MountainWest unsecured senior notes, 3.91%, due in 2038
Debt Instrument [Line Items]
Long-term debt, gross	0		147,735
Fair Value \| Other debt obligations
Debt Instrument [Line Items]
Long-term debt, gross	$ 118,314		$ 50,003

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Capitalized and Debt Portion of AFUDC (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Debt portion	$ 3,535	$ 1,046	$ 3,202
Equity portion	0	0	4,724
AFUDC capitalized as part of regulated operations plant	$ 3,535	$ 1,046	$ 7,926
AFUDC rate	2.64%	0.96%	5.51%

Revenue (Tables)

12 Months Ended

Dec. 31, 2022

Revenue from Contract with Customer [Abstract]

Summary of Revenue Disaggregated by Service Type and Contract Type


	December 31,
(Thousands of dollars)	2022		2021		2020
Residential	$	1,324,794	$	1,035,612	$	958,520
Small commercial	378,520		270,214		221,541
Large commercial	85,234		57,371		44,633
Industrial/other	50,894		42,313		26,242
Transportation	100,642		92,240		88,215
Revenue from contracts with customers	1,940,084		1,497,750		1,339,151
Alternative revenue program revenues (deferrals)	(18,478)		13,181		12,140
Other revenues (a)	13,463		10,859		(706)
Total Regulated operations revenues	$	1,935,069	$	1,521,790	$	1,350,585

The following tables display Centuri’s revenue from contracts with customers disaggregated by service type and contract type:


	December 31,
(Thousands of dollars)	2022		2021		2020
Service Types:
Gas infrastructure services	$	1,531,818	$	1,302,340	$	1,261,160
Electric power infrastructure services	778,124		525,202		411,826
Other	450,385		331,119		275,302
Total Utility infrastructure services revenues	$	2,760,327	$	2,158,661	$	1,948,288


	December 31,
(Thousands of dollars)	2022		2021		2020
Contract Types:
Master services agreement	$	2,342,220	$	1,652,978	$	1,490,009
Bid contract	418,107		505,683		458,279
Total Utility infrastructure services revenues	$	2,760,327	$	2,158,661	$	1,948,288

Unit-price contracts	$	1,608,131	$	1,369,082	$	1,356,640
Fixed-price contracts	498,039		267,742		157,701
Time and materials contracts	654,157		521,837		433,947
Total Utility infrastructure services revenues	$	2,760,327	$	2,158,661	$	1,948,288


(Thousands of dollars)	December 31, 2022
Regulated gas transportation and storage revenues	$	248,304
NGL revenues	5,983
Other revenues	10,152
Revenue from contracts with customers	264,439
Other revenues	174
Total Regulated operations revenues	$	264,613

Summary of Information about Receivables, Revenue Earned on Contracts in Progress in Excess of Billings, Which are Included Within Accounts Receivable, Net of Allowances, and Amounts Billed in Excess of Revenue Earned on Contracts


	December 31,
(Thousands of dollars)	2022		2021
Contracts receivable, net	$	394,022	$	296,005
Revenue earned on contracts in progress in excess of billings	238,059		214,774
Amounts billed in excess of revenue earned on contracts	35,769		11,860

Schedule of Utility Infrastructure Services Contracts Receivable

Utility infrastructure services contracts receivable consists of the following:


	December 31,
(Thousands of dollars)	2022		2021
Billed on completed contracts and contracts in progress	$	395,771	$	292,770
Other receivables	2,569		3,492
Contracts receivable, gross	398,340		296,262
Allowance for doubtful accounts	(4,318)		(257)
Contracts receivable, net	$	394,022	$	296,005

Receivables and Related Allowances - Schedule of Percent of Customers by State (Details)	12 Months Ended
	Dec. 31, 2022
Arizona
Receivables And Related Allowances [Line Items]
Percent of customers by state	54.00%
Nevada
Receivables And Related Allowances [Line Items]
Percent of customers by state	37.00%
California
Receivables And Related Allowances [Line Items]
Percent of customers by state	9.00%

Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI")

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI")

Note 6 - Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI")

The following information provides insight into amounts impacting the Company’s and Southwest’s Other comprehensive income (loss), both before and after-tax impacts, within the Consolidated Statements of Comprehensive Income, which also impact Accumulated other comprehensive income (“AOCI”) in the Consolidated Balance Sheets and the Consolidated Statements of Equity.

Related Tax Effects Allocated to Each Component of Other Comprehensive Income (Loss):


	Year Ended December 31,
	2022						2021						2020
(Thousands of dollars)	Before- Tax Amount		Tax (Expense) or Benefit (1)		Net-of- Tax Amount		Before- Tax Amount		Tax (Expense) or Benefit (1)		Net-of- Tax Amount		Before- Tax Amount		Tax (Expense) or Benefit (1)		Net-of- Tax Amount
Defined benefit pension plans:
Net actuarial gain/(loss)	$	4,079	$	(980)	$	3,099	$	59,176	$	(14,202)	$	44,974	$	(57,539)	$	13,809	$	(43,730)
Amortization of prior service cost	175		(42)		133		959		(230)		729		1,155		(277)		878
Amortization of net actuarial (gain)/loss	34,818		(8,357)		26,461		44,597		(10,703)		33,894		37,830		(9,079)		28,751

Regulatory adjustment	(28,232)		6,775		(21,457)		(88,194)		21,167		(67,027)		7,435		(1,785)		5,650
Pension plans other comprehensive income (loss)	10,840		(2,604)		8,236		16,538		(3,968)		12,570		(11,119)		2,668		(8,451)
FSIRS (designated hedging activities):
Amounts reclassified into net income	545		(129)		416		2,174		(522)		1,652		3,247		(780)		2,467
FSIRS other comprehensive income (loss)	545		(129)		416		2,174		(522)		1,652		3,247		(780)		2,467
Total other comprehensive income (loss) –Southwest Gas Corporation	11,385		(2,733)		8,652		18,712		(4,490)		14,222		(7,872)		1,888		(5,984)
Foreign currency translation adjustments:
Translation adjustments	(6,133)		—		(6,133)		20		—		20		1,713		—		1,713
Foreign currency other comprehensive income (loss)	(6,133)		—		(6,133)		20		—		20		1,713		—		1,713
Total other comprehensive income (loss) – Southwest Gas Holdings, Inc.	$	5,252	$	(2,733)	$	2,519	$	18,732	$	(4,490)	$	14,242	$	(6,159)	$	1,888	$	(4,271)

The following table represents a rollforward of AOCI, presented on the Company’s Consolidated Balance Sheets and its Consolidated Statements of Equity:


	Defined Benefit Plans						FSIRS						Foreign Currency Items
(Thousands of dollars)	Before-Tax		Tax (Expense) Benefit (4)		After-Tax		Before- Tax		Tax (Expense) Benefit (4)		After-Tax		Before- Tax		Tax (Expense) Benefit		After-Tax		AOCI
Beginning Balance AOCI December 31, 2021	$	(61,182)	$	14,685	$	(46,497)	$	(545)	$	129	$	(416)	$	152	$	—	$	152	$	(46,761)
Net actuarial gain/(loss)	4,079		(980)		3,099		—		—		—		—		—		—		3,099
Translation adjustments	—		—		—		—		—		—		(6,133)		—		(6,133)		(6,133)
Other comprehensive income before reclassifications	4,079		(980)		3,099		—		—		—		(6,133)		—		(6,133)		(3,034)
FSIRS amount reclassified from AOCI (1)	—		—		—		545		(129)		416		—		—		—		416
Amortization of prior service cost (2)	175		(42)		133		—		—		—		—		—		—		133
Amortization of net actuarial loss (2)	34,818		(8,357)		26,461		—		—		—		—		—		—		26,461

Regulatory adjustment (3)	(28,232)		6,775		(21,457)		—		—		—				—		—		(21,457)
Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	10,840		(2,604)		8,236		545		(129)		416		(6,133)		—		(6,133)		2,519
Ending Balance AOCI December 31, 2022	$	(50,342)	$	12,081	$	(38,261)	$	—	$	—	$	—	$	(5,981)	$	—	$	(5,981)	$	(44,242)

(1)The FSIRS reclassification amount is included in Net interest deductions on the Company’s Consolidated Statements of Income.

(2)These AOCI components are included in the computation of net periodic benefit cost (see Note 11 - Pension and Other Postretirement Benefits for additional details).

(4) Tax amounts are calculated using a 24% rate.

The following table represents a rollforward of AOCI, presented on Southwest’s Consolidated Balance Sheets:


	Defined Benefit Plans						FSIRS
(Thousands of dollars)	Before-Tax		Tax (Expense) Benefit (9)		After- Tax		Before- Tax		Tax (Expense) Benefit (9)		After- Tax		AOCI
Beginning Balance AOCI December 31, 2021	$	(61,182)	$	14,685	$	(46,497)	$	(545)	$	129	$	(416)	$	(46,913)
Net actuarial gain/(loss)	4,079		(980)		3,099		—		—		—		3,099
Other comprehensive loss before reclassifications	4,079		(980)		3,099		—		—		—		3,099
FSIRS amount reclassified from AOCI (6)	—		—		—		545		(129)		416		416
Amortization of prior service cost (7)	175		(42)		133		—		—		—		133
Amortization of net actuarial loss (7)	34,818		(8,357)		26,461		—		—		—		26,461

Regulatory adjustment (8)	(28,232)		6,775		(21,457)		—		—		—		(21,457)
Net current period other comprehensive income (loss) attributable to Southwest Gas Corporation	10,840		(2,604)		8,236		545		(129)		416		8,652
Ending Balance AOCI December 31, 2022	$	(50,342)	$	12,081	$	(38,261)	$	—	$	—	$	—	$	(38,261)

(6) The FSIRS reclassification amount is included in Net interest deductions on Southwest’s Consolidated Statements of Income.

(7) These AOCI components are included in the computation of net periodic benefit cost (see Note 11 - Pension and Other Postretirement Benefits for additional details).

(9) Tax amounts are calculated using a 24% rate.

The following table represents amounts (before income tax impacts) included in AOCI (in the tables above), that have not yet been recognized in net periodic benefit cost:


	Year Ended December 31,
(Thousands of dollars)	2022		2021
Net actuarial loss	$	(360,113)	$	(399,010)
Prior service cost	(1,353)		(1,528)
Less: amount recognized in regulatory assets	311,124		339,356
Recognized in AOCI	$	(50,342)	$	(61,182)

See Note 11 - Pension and Other Postretirement Benefits for more information on the defined benefit pension plans.

Audit Information	12 Months Ended
Audit Information	Dec. 31, 2022
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Las Vegas, Nevada
Auditor Firm ID	238
Southwest Gas Corporation
Auditor [Line Items]
Auditor Name	PricewaterhouseCoopers LLP
Auditor Location	Las Vegas, Nevada
Auditor Firm ID	238

Receivables and Related Allowances - Narrative (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2022 USD ($) state	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Receivables And Related Allowances [Line Items]
Number of states in which entity operates \| state	3
Accounts receivable, extending period	1 month
Threshold period after inactivation for write-off of accounts receivable	2 months
Customer accounts receivable	$ 866,246	$ 707,127
Allowance for doubtful accounts	$ 4,830	$ 3,259	$ 4,334	$ 2,095
Centuri
Receivables And Related Allowances [Line Items]
Threshold period after inactivation for write-off of accounts receivable	60 days
Customer accounts receivable	$ 632,100
Allowance for doubtful accounts	$ 4,300

Other Comprehensive Income and Accumulated Other Comprehensive Income ("AOCI") - Amount Recognized Before Income Tax Associated with Defined Benefit Plans in Accumulated Other Comprehensive Income (Detail) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Equity [Abstract]
Net actuarial loss	$ (360,113)	$ (399,010)
Prior service cost	(1,353)	(1,528)
Less: amount recognized in regulatory assets	311,124	339,356
Recognized in AOCI	$ (50,342)	$ (61,182)

Regulated Operations Plant and Leases (Tables)

12 Months Ended

Dec. 31, 2022

Regulated Operations [Abstract]

Schedule of Net Utility Plant

Major classes of regulated operations plant and their respective balances as of December 31, 2022 and 2021 were as follows:


	December 31,
(Thousands of dollars)	2022		2021		2021
	Southwest Gas Holdings Inc.*				Southwest Gas Corporation
Gas plant:
Storage	$	104,218	$	437,793	$	103,874
Transmission	399,357		1,917,529		397,590
Distribution	8,039,793		7,506,489		7,506,489
General	505,109		530,346		496,643
Software and software-related intangibles	389,496		380,372		380,372
Other	15,934		17,161		16,607
	9,453,907		10,789,690		8,901,575
Less: accumulated depreciation and amortization	(2,674,157)		(3,397,736)		(2,538,508)
Construction work in progress	244,750		202,068		183,485
Net regulated operations plant	$	7,024,500	$	7,594,022	$	6,546,552

Schedule of Depreciation and Amortization Expense

Depreciation and amortization expense on gas plant, including intangibles, was as follows:


(Thousands of dollars)	2022		2021		2020
Depreciation and amortization expense	$	243,857	$	230,245	$	215,636

Schedule of Components of Lease Expense, and Supplemental Cash Flow Information Related to Leases

The components of lease expense for Centuri were as follows:


(Thousands of dollars)	2022		2021		2020
Operating lease cost	$	17,881	$	15,279	$	14,294

Finance lease cost:
Amortization of ROU assets	7,702		2,138		140
Interest on lease liabilities	1,520		278		37
Total finance lease cost	9,222		2,416		177
Short-term lease cost	120,339		103,800		19,806
Total lease cost	$	147,442	$	121,495	$	34,277

Supplemental cash flow information related to Centuri leases for the years ended December 31, 2022, 2021, and 2020 was as follows:


(Thousands of dollars)	2022		2021		2020
Cash paid for amounts included in the measurement of lease liabilities:
Operating cash flows from operating leases	$	16,725	$	14,669	$	12,889
Operating cash flows from finance leases	1,520		278		36
Financing cash flows from finance leases	11,985		3,547		199

ROU assets obtained in exchange for lease obligations:
Operating leases	$	22,653	$	11,597	$	19,372
Finance leases	28,861		3,332		361

Schedule of Supplemental Information Related to Leases Included in Balance Sheet

Supplemental information related to Centuri leases, including location in the Consolidated Balance Sheets, is as follows:


(Thousands of dollars)	December 31,
	2022			2021
Operating leases:
Other property and investments	$	85,270		$	80,638

Other current liabilities	$	13,863		$	12,185
Other deferred credits and other long-term liabilities	77,119			72,930
Total operating lease liabilities	$	90,982		$	85,115

Finance leases:
Other property and investments	$	51,313		$	30,705

Other current liabilities	$	12,028		$	8,858
Other deferred credits and other long-term liabilities	34,238			20,585
Total finance lease liabilities	$	46,266		$	29,443

Weighted average remaining lease term (in years)
Operating leases	6.66			7.57
Finance leases	4.33			3.92

Weighted average discount rate
Operating leases	4.06		%	3.95		%
Finance leases	3.95		%	2.58		%

Schedule of Maturities of Operating Lease Liabilities

The following is a schedule of maturities of Centuri lease liabilities as of December 31, 2022:


(Thousands of dollars)	Operating Leases		Finance Leases
2023	$	17,392	$	13,657
2024	15,267		12,225
2025	12,595		9,852
2026	10,646		7,263
2027	10,146		5,311
Thereafter	43,078		2,374
Total lease payments	109,124		50,682
Less imputed interest	18,142		4,416
Total	$	90,982	$	46,266

Schedule of Maturities of Finance Lease Liabilities

The following is a schedule of maturities of Centuri lease liabilities as of December 31, 2022:


(Thousands of dollars)	Operating Leases		Finance Leases
2023	$	17,392	$	13,657
2024	15,267		12,225
2025	12,595		9,852
2026	10,646		7,263
2027	10,146		5,311
Thereafter	43,078		2,374
Total lease payments	109,124		50,682
Less imputed interest	18,142		4,416
Total	$	90,982	$	46,266

Revenue - Schedule of Utility Infrastructure Services Contracts Receivable (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Disaggregation of Revenue [Line Items]
Contracts receivable, net	$ 394,022	$ 296,005
Utility Infrastructure Services
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	398,340	296,262
Allowance for doubtful accounts	(4,318)	(257)
Contracts receivable, net	394,022	296,005
Utility Infrastructure Services \| Billed on completed contracts and contracts in progress
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	395,771	292,770
Utility Infrastructure Services \| Other receivables
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	$ 2,569	$ 3,492

Background, Organization, and Summary of Significant Accounting Policies - Schedule of Goodwill (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 1,781,332
Goodwill, ending balance	787,250	$ 1,781,332
Natural Gas Distribution
Goodwill [Roll Forward]
Goodwill, beginning balance	10,095	10,095
Foreign currency translation adjustment	0	0
Goodwill, ending balance	11,155	10,095
Natural Gas Distribution \| Riggs Distler
Goodwill [Roll Forward]
Goodwill from acquisition		0
Measurement period adjustments	0
Natural Gas Distribution \| Graham County
Goodwill [Roll Forward]
Goodwill from acquisition	1,060
Utility Infrastructure Services
Goodwill [Roll Forward]
Goodwill, beginning balance	785,058	335,089
Foreign currency translation adjustment	(7,039)	468
Goodwill, ending balance	776,095	785,058
Utility Infrastructure Services \| Riggs Distler
Goodwill [Roll Forward]
Goodwill from acquisition		449,501
Measurement period adjustments	(1,924)
Utility Infrastructure Services \| Graham County
Goodwill [Roll Forward]
Goodwill from acquisition	0
Pipeline and Storage
Goodwill [Roll Forward]
Goodwill, beginning balance	986,200
Goodwill, ending balance		986,200
Natural Gas Distribution and Utility Infrastructure Services segments
Goodwill [Roll Forward]
Goodwill, beginning balance	795,153	345,184
Foreign currency translation adjustment	(7,039)	468
Goodwill, ending balance	787,250	795,153
Natural Gas Distribution and Utility Infrastructure Services segments \| Riggs Distler
Goodwill [Roll Forward]
Goodwill from acquisition		$ 449,501
Measurement period adjustments	(1,924)
Natural Gas Distribution and Utility Infrastructure Services segments \| Graham County
Goodwill [Roll Forward]
Goodwill from acquisition	$ 1,060

Common Stock

12 Months Ended

Dec. 31, 2022

Equity [Abstract]

Common Stock

Note 7 - Common Stock

Shares of the Company’s common stock are publicly traded on the New York Stock Exchange, under the ticker symbol “SWX.” Share-based compensation related to Southwest and Centuri is based on awards to be issued in shares of Southwest Gas Holdings, Inc.

In December 2020, the Company and Southwest jointly filed with the SEC an automatic shelf registration statement (File No. 333-251074), or a “Universal Shelf,” which became effective upon filing and includes a prospectus detailing the Company’s ability to offer and sell, from time to time in amounts at prices and on terms that will be determined at the time of such offering, any combination of common stock, preferred stock, debt securities (which may or may not be guaranteed by one or more of its directly or indirectly wholly owned subsidiaries if indicated in the relevant prospectus supplement), guarantees of debt securities issued by Southwest, depository shares, warrants to purchase common stock, preferred stock or depository shares issued by the Company or debt securities issued by the Company or Southwest, units and rights. Additionally as part of the Universal Shelf, Southwest may offer and sell, from time to time in amounts at prices and on terms that will be determined at the time of such offering, any combination of debt securities (which may or may not be guaranteed by one or more of its directly or indirectly wholly owned subsidiaries if indicated in the relevant prospectus supplement) and guarantees of debt securities issued by the Company or by one or more of its directly or indirectly wholly owned subsidiaries if indicated in the relevant prospectus supplement.

On April 8, 2021, the Company entered into a Sales Agency Agreement between the Company and BNY Mellon Capital Markets, LLC and J.P. Morgan Securities LLC (the “Equity Shelf Program”) for the offer and sale of up to $500 million of common stock from time to time in an at-the-market offering program. The shares are issued pursuant to the Company’s Universal Shelf. There was no activity under the Equity Shelf Program during the year ended December 31, 2022. The following table provides the life-to-date activity under that program through December 31, 2022:


Gross proceeds	$	158,180,343
Less: agent commissions	(1,581,803)
Net proceeds	$	156,598,540
Number of shares sold	2,302,407
Weighted average price per share	$	68.70

As of December 31, 2022, the Company had approximately $342 million of common stock available for future issuance under the program. Net proceeds from the sale of shares of common stock under the Equity Shelf Program are intended for general corporate purposes, including the acquisition of property for the construction, completion, extension, or improvement of pipeline systems and facilities located in and around the communities served by Southwest.

In March 2022, the Company issued, through a separate prospectus supplement under the Universal Shelf, an aggregate of 6.325 million shares of common stock, in an underwritten public offering price of $74.00 per share, resulting in proceeds to the Company of $452.3 million, net of an underwriters’ discount of $15.8 million. The Company used the net proceeds to repay a portion of the outstanding borrowings under the 364-day term loan credit agreement that was used to initially fund the MountainWest acquisition.

During 2022, the Company issued approximately 230,000 shares of common stock through the Restricted Stock/Unit Plan and Omnibus Incentive Plan.

Additionally during 2022, the Company issued 142,000 shares of common stock through the Dividend Reinvestment and Stock Purchase Plan, raising proceeds of approximately $10.5 million.

As of December 31, 2022, there were 3.3 million shares of common stock registered and available for issuance under the provisions of the various stock issuance plans, which does not include the amount of common stock available that is separately disclosed with respect to the Equity Shelf Program above.

Acquisitions and Dispositions (Tables)

12 Months Ended

Dec. 31, 2022

Business Combination and Dispositions [Abstract]

Business Acquisition, Pro Forma Information

The following unaudited pro forma financial information reflects the consolidated results of operations of the Company assuming the Riggs Distler and MountainWest acquisitions had taken place on January 1, 2020. The most significant pro forma adjustments relate to: (i) reflecting approximately $48.7 million in transaction costs in the year ended December 31, 2020, and excluding such costs from the year ended December 31, 2021, and (ii) reflecting incremental interest expense of $48.4 million in 2021, and approximately $52.1 million in the comparable 2020 period. The pro forma financial information has been prepared for comparative purposes only, and is not intended to be indicative of what the Company’s results would have been had the acquisition occurred at the beginning of the periods presented or of what results may be in the future, for a number of reasons. The reasons include, but are not limited to, differences between the assumptions used to prepare the pro forma information, potential cost savings from operating efficiencies, nor the impact of incremental costs incurred in integrating the businesses.

Amounts below are in millions of dollars, except per share amounts.


	Unaudited
	Year Ended December 31,
	2021		2020
Total operating revenues	$	4,236	$	3,980
Net income attributable to Southwest Gas Holdings, Inc.	$	278	$	276
Basic earnings per share	$	4.70	$	4.93
Diluted earnings per share	$	4.69	$	4.93

Schedule of Assets Held for Sale


(Thousands of dollars)
Regulated operations plant, net of accumulated depreciation of $907 million	$	957,729
Other property and investments	49,546
Other current assets (1)	188,629
Goodwill, net of accumulated impairment of $449.6 million	508,395
Deferred charges and other assets (2)	39,050
Total assets	1,743,349
Less: cost to sell	5,819
Total current assets, held for sale	$	1,737,530

Other current liabilities (3)	$	55,188
Long-term debt	448,862
Other deferred credits and liabilities (3)	140,195
Total current liabilities, held for sale	$	644,245

(2) Includes regulatory assets of $30.1 million.

- Definition

Tabular disclosure of information related to a disposal group. Includes, but is not limited to, a discontinued operation, disposal classified as held-for-sale or disposed of by means other than sale or disposal of an individually significant component.

+ References

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Reference 4: http://fasb.org/us-gaap/role/ref/legacyRef
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Reference 10: http://fasb.org/us-gaap/role/ref/legacyRef
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-SubTopic 20
-Section 50
-Paragraph 1
-URI https://asc.fasb.org/extlink&oid=109222650&loc=d3e1361-107760

Reference 11: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5A
-URI https://asc.fasb.org/extlink&oid=109222650&loc=SL51721671-107760

Reference 12: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 5B
-URI https://asc.fasb.org/extlink&oid=109222650&loc=SL51721673-107760

Reference 13: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 205
-SubTopic 20
-Section 50
-Paragraph 4A
-URI https://asc.fasb.org/extlink&oid=109222650&loc=SL51721663-107760

+ Details

Debt - Summary of Effective Interest Rates on Variable-Rate IDRBs (Details)	Dec. 31, 2022	Dec. 31, 2021
2003 Series A, due 2038
Debt Instrument [Line Items]
Effective interest rates	4.68%	0.91%
2008 Series A, due 2038
Debt Instrument [Line Items]
Effective interest rates	4.84%	0.90%
2009 Series A, due 2039
Debt Instrument [Line Items]
Effective interest rates	4.67%	0.88%
Tax-exempt Series A, due 2028
Debt Instrument [Line Items]
Effective interest rates	4.30%	0.92%

Redeemable Noncontrolling Interests

12 Months Ended

Dec. 31, 2022

Noncontrolling Interest [Abstract]

Redeemable Noncontrolling Interests

Note 14 - Redeemable Noncontrolling Interests

In connection with the acquisition of Linetec in November 2018, the previous owner retained a 20% equity interest in Linetec, the reduction of which is subject to certain rights based on the passage of time or upon the occurrence of certain triggering events. Effective January 2022, the Company, by means of Centuri, has the right, but not the obligation, to purchase at fair value (subject to a floor) a portion of the interest held by the noncontrolling party, and in incremental amounts each year thereafter. In March 2022, the parties agreed to a partial redemption based on these provisions, and as a result, Centuri paid $39.6 million to the previous owner of Linetec for a 5% equity interest in Linetec, thereby reducing the balance continuing to be redeemable to 15% under the terms of the original agreement. In order to fund the redemption, Southwest Gas Holdings, Inc. contributed capital to Centuri. The shares subject to the election accumulate (if earlier elections are not made) such that 100% of the interest retained by the noncontrolling party is subject to the election beginning in 2024. If the Company does not exercise its rights at each or any of the specified intervals, the noncontrolling party has the ability, but not the obligation, to exit their investment retained, by requiring Centuri to purchase a similar portion of their interest up to the maximum cumulative amounts specified at each interval discussed above. The outstanding noncontrolling interest is not subject to minimum purchase provisions and, following the eligibility dates for the elections, they do not expire. The redemption price represents the greater of fair value of the ownership interest to be redeemed on the redemption date or a floor amount under the terms of the agreement. The Company has determined that this noncontrolling interest is a redeemable noncontrolling interest and, in accordance with SEC guidance, is classified as mezzanine equity (temporary equity) in the Company’s Consolidated Balance Sheets.

In November 2021, certain members of Riggs Distler management acquired a 1.42% interest in Drum Parent LLC (“Drum”), which is subject to certain rights based on the passage of time or upon the occurrence of certain triggering events. Effective January 2027 and each calendar year thereafter or upon the occurrence of certain triggering events, the Company, through Centuri, has the right, but not the obligation, to purchase all of the interest held by the noncontrolling party at fair value. If the Company does not exercise its rights in accordance with the timeline noted, or upon the occurrence of certain other triggering events, the noncontrolling party has the ability, but not the obligation, to exit their investment retained by requiring Centuri to purchase all of their outstanding interest. The outstanding noncontrolling interest is not subject to minimum purchase provisions and, following the eligibility date for the election, they do not expire. The redemption price represents the fair value of the ownership interest to be redeemed on the redemption date under the terms of the agreement. A portion of the redeemable noncontrolling interest acquired was funded through promissory notes made to noncontrolling interest holders bearing interest at the prime rate plus 2%. The promissory notes are payable by the noncontrolling interest holders upon certain triggering events including, but not limited to, termination of employment or the redemption of any interest under the agreement. The promissory notes are recognized as a reduction to the Company’s stockholders’ equity. Additionally, the Company has determined that this noncontrolling interest is a redeemable noncontrolling interest and, in accordance with SEC guidance, is classified as mezzanine equity (temporary equity) in the Company’s Consolidated Balance Sheets.

Significant changes in the value of the total redeemable noncontrolling interests, above a floor determined at the establishment date, are recognized as they occur, and the carrying value is adjusted as necessary at each reporting date. The fair value is

estimated using a market approach that utilizes certain financial metrics from guideline public companies of similar industry and operating characteristics. Based on the fair value model employed, the estimated redemption value of the Linetec redeemable noncontrolling interest decreased by approximately $3.3 million during the year ended December 31, 2022. Adjustment to the redemption value also impacted retained earnings, as reflected in the Company’s Consolidated Statement of Equity, but did not impact net income.

The following depicts changes to the balances of the redeemable noncontrolling interests:


	Linetec		Drum		Total
(Thousands of dollars)
Balance, December 31, 2020	$	165,716	$	—	$	165,716
Redeemable noncontrolling interest acquired	—		12,562		12,562
Net income attributable to redeemable noncontrolling interests	6,416		7		6,423
Redemption value adjustments	12,016		—		12,016
Balance, December 31, 2021	184,148		12,569		196,717

Net income attributable to redeemable noncontrolling interests	5,591		15		5,606
Redemption value adjustments	(3,325)		—		(3,325)
Redemption of equity interest from noncontrolling party	(39,649)		—		(39,649)
Balance, December 31, 2022	$	146,765	$	12,584	$	159,349

CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Dec. 31, 2022	Dec. 31, 2021
Statement of Financial Position [Abstract]
Common stock, par (in USD per share)	$ 1	$ 1
Common stock, authorized (in shares)	120,000,000	120,000,000
Common stock, issued (in shares)	67,119,143	60,422,081
Common stock, outstanding (in shares)	67,119,143	60,422,081

Receivables and Related Allowances - Schedule of Accounts Receivable (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021
Receivables [Abstract]
Gas utility customer accounts receivable balance	$ 225,317	$ 169,114

Background, Organization, and Summary of Significant Accounting Policies - Other Income (Deductions) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Other income (deductions)
Interest income	$ 16,183	$ 5,113	$ 4,015
Equity AFUDC	0	0	4,724
Total other income (deductions)	(6,189)	(3,499)	(6,789)
Corporate and administrative
Other income (deductions)
Total other income (deductions)	(263)	(7)	8
Southwest Gas Corporation
Other income (deductions)
Change in COLI policies	(5,400)	8,800	9,200
Interest income	16,183	5,113	4,015
Equity AFUDC	0	0	4,724
Other components of net periodic benefit cost	(751)	(14,021)	(20,022)
Miscellaneous income and (expense)	(16,916)	(4,451)	(4,507)
Total other income (deductions)	(6,884)	(4,559)	(6,590)
Centuri And MountainWest
Other income (deductions)
Equity AFUDC	465	0	0
Miscellaneous income and (expense)	(3,113)	863	(271)
Foreign transaction gain (loss)	977	(22)	(16)
Equity in earnings of unconsolidated investments	$ 2,629	$ 226	$ 80

Segment Information (Tables)

12 Months Ended

Dec. 31, 2022

Segment Reporting [Abstract]

Schedule of Accounts Receivable for Services

Accounts receivable for these services, which are not eliminated during consolidation, are presented in the table below:


	December 31,
(Thousands of dollars)	2022		2021
Accounts receivable for Centuri services	$	18,067	$	15,166

Schedule of Revenues by Geographic Area

The following table presents the amount of revenues by geographic area:


	December 31,
(Thousands of dollars)	2022		2021		2020
Revenues (a)
United States	$	4,637,557	$	3,411,018	$	3,057,041
Canada	322,452		269,433		241,832
Total	$	4,960,009	$	3,680,451	$	3,298,873

(a)Revenues are attributed to countries based on the location of customers.

Schedule of Segment Reporting Information

The financial information pertaining to each segment as of and for the three years ended December 31, 2022, 2021, and 2020 are as follows:


	Year Ended December 31, 2022
(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Pipeline and Storage		Other		Total
Revenues from external customers	$	1,935,069	$	2,625,669	$	264,613	$	—	$	4,825,351
Intersegment sales	—		134,658		—		—		134,658
Total	$	1,935,069	$	2,760,327	$	264,613	$	—	$	4,960,009
Interest income	$	16,183	$	—	$	—	$	—	$	16,183
Interest expense	$	115,880	$	61,371	$	18,185	$	47,314	$	242,750
Depreciation and amortization	$	263,043	$	155,353	$	52,059	$	—	$	470,455
Income tax expense (benefit)	$	30,541	$	5,727	$	(89,668)	$	(22,253)	$	(75,653)
Segment net income (loss)	$	154,380	$	2,065	$	(283,733)	$	(76,002)	$	(203,290)
Segment assets*	$	8,803,681	$	2,642,272	$	1,743,349	$	7,312	$	13,196,614
Capital expenditures	$	683,131	$	130,166	$	46,124	$	—	$	859,421


	Year Ended December 31, 2021
(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Pipeline and Storage		Other		Total
Revenues from external customers	$	1,521,790	$	2,056,315	$	—	$	—	$	3,578,105
Intersegment sales	—		102,346		—		—		102,346
Total	$	1,521,790	$	2,158,661	$	—	$	—	$	3,680,451
Interest income	$	5,113	$	—	$	—	$	—	$	5,113
Interest expense	$	97,560	$	20,999	$	—	$	639	$	119,198
Depreciation and amortization	$	253,398	$	117,643	$	—	$	—	$	371,041
Income tax expense	$	29,338	$	18,776	$	—	$	(8,466)	$	39,648
Segment net income (loss)	$	187,135	$	40,420	$	—	$	(26,776)	$	200,779
Segment assets	$	7,950,263	$	2,579,748	$	2,187,582	$	47,664	$	12,765,257
Capital expenditures	$	601,983	$	113,643	$	—	$	—	$	715,626


	Year Ended December 31, 2020
(Thousands of dollars)	Natural Gas Distribution		Utility Infrastructure Services		Other		Total
Revenues from external customers	$	1,350,585	$	1,813,429	$	—	$	3,164,014
Intersegment sales	—		134,859		—		134,859
Total	$	1,350,585	$	1,948,288	$	—	$	3,298,873
Interest income	$	4,015	$	—	$	—	$	4,015
Interest expense	$	101,148	$	9,269	$	1,060	$	111,477
Depreciation and amortization	$	235,295	$	96,732	$	—	$	332,027
Income tax expense	$	35,755	$	31,128	$	(1,130)	$	65,753
Segment net income (loss)	$	159,118	$	74,862	$	(1,656)	$	232,324
Segment assets	$	7,256,636	$	1,475,237	$	3,980	$	8,735,853
Capital expenditures	$	692,216	$	132,889	$	—	$	825,105

Regulated Operations Plant and Leases - Schedule of Regulated Operations Plant (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	$ 9,453,907	$ 10,789,690
Less: accumulated depreciation and amortization	(2,674,157)	(3,397,736)
Construction work in progress	244,750	202,068
Net regulated operations plant	7,024,500	7,594,022
Southwest Gas Corporation
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	9,453,907	8,901,575
Less: accumulated depreciation and amortization	(2,674,157)	(2,538,508)
Construction work in progress	244,750	183,485
Net regulated operations plant	7,024,500	6,546,552
Storage
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	104,218	437,793
Storage \| Southwest Gas Corporation
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant		103,874
Transmission
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	399,357	1,917,529
Transmission \| Southwest Gas Corporation
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant		397,590
Distribution
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	8,039,793	7,506,489
Distribution \| Southwest Gas Corporation
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant		7,506,489
General
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	505,109	530,346
General \| Southwest Gas Corporation
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant		496,643
Software and software-related intangibles
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	389,496	380,372
Software and software-related intangibles \| Southwest Gas Corporation
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant		380,372
Other
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant	$ 15,934	17,161
Other \| Southwest Gas Corporation
Public Utility, Property, Plant and Equipment [Line Items]
Gas plant		$ 16,607