10-Q

UNITED STATES

SECURITIES AND EXCHANGE COMMISSION

WASHINGTON, D.C. 20549

Form 10-Q

☒ QUARTERLY REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

For the quarterly period ended March 31, 2021

OR

☐ TRANSITION REPORT PURSUANT TO SECTION 13 OR 15(d) OF THE SECURITIES EXCHANGE ACT OF 1934

Commission         File Number	Exact name of registrant as specified in its charter and principal office address and telephone number			State of Incorporation	I.R.S. Employer Identification No.
001-37976	Southwest Gas Holdings, Inc.			Delaware	81-3881866
	8360 S. Durango Drive
	Post Office Box 98510
	Las Vegas,	Nevada	89193-8510
	(702)	876-7237
1-7850	Southwest Gas Corporation			California	88-0085720
	8360 S. Durango Drive
	Post Office Box 98510
	Las Vegas,	Nevada	89193-8510
	(702)	876-7237

Securities registered pursuant to Section 12(b) of the Act:
Title of each class	Trading Symbol	Name of each exchange on which registered
Southwest Gas Holdings, Inc. Common Stock, $1 Par Value	SWX	New York Stock Exchange

Indicate by check mark whether each registrant: (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that each registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.    Yes  ☒    No  ☐

Indicate by check mark whether each registrant has submitted electronically every Interactive Data File required to be submitted pursuant to Rule 405 of Regulation S-T (§232.405 of this chapter) during the preceding 12 months (or for such shorter period that each registrant was required to submit such files).    Yes  ☒    No  ☐

Indicate by check mark whether each registrant is a large accelerated filer, an accelerated filer, a non-accelerated filer, a smaller reporting company, or an emerging growth company. See the definitions of “large accelerated filer,” “accelerated filer,” “non-accelerated filer,” “smaller reporting company,” and “emerging growth company” in Rule 12b-2 of the Exchange Act.

Southwest Gas Holdings, Inc.:

Large accelerated filer	☒	Accelerated filer	☐
Non-accelerated filer	☐	Smaller reporting company	☐
Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Southwest Gas Corporation:

Large accelerated filer	☐	Accelerated filer	☐
Non-accelerated filer	☒	Smaller reporting company	☐
Emerging growth company	☐

If an emerging growth company, indicate by check mark if the registrant has elected not to use the extended transition period for complying with any new or revised financial accounting standards provided pursuant to Section 13(a) of the Exchange Act.  ☐

Indicate by check mark whether each registrant is a shell company (as defined in Rule 12b-2 of the Exchange Act).    Yes  ☐    No  ☒

Indicate the number of shares outstanding of each of the issuer’s classes of common stock as of the latest practicable date.

Southwest Gas Holdings, Inc. Common Stock, $1 Par Value, 58,001,396 shares as of April 30, 2021.

All of the outstanding shares of common stock ($1 par value) of Southwest Gas Corporation were held by Southwest Gas Holdings, Inc. as of April 30, 2021.

SOUTHWEST GAS CORPORATION MEETS THE CONDITIONS SET FORTH IN GENERAL INSTRUCTION (H)(1)(a) and (b) OF FORM 10-Q AND IS THEREFORE FILING THIS REPORT WITH THE REDUCED DISCLOSURE FORMAT AS PERMITTED BY GENERAL INSTRUCTION H(2).

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

FILING FORMAT

This quarterly report on Form 10-Q is a combined report being filed by two separate registrants: Southwest Gas Holdings, Inc. and Southwest Gas Corporation. Except where the content clearly indicates otherwise, any reference in the report to “we,” “us” or “our” is to the holding company or the consolidated entity of Southwest Gas Holdings, Inc. and all of its subsidiaries, including Southwest Gas Corporation, which is a distinct registrant that is a wholly owned subsidiary of Southwest Gas Holdings, Inc. Information contained herein relating to any individual company is filed by such company on its own behalf. Each company makes representations only as to itself and makes no other representation whatsoever as to any other company.

Part I—Financial information in this Quarterly Report on Form 10-Q includes separate financial statements (i.e., balance sheets, statements of income, statements of comprehensive income, statements of cash flows, and statements of equity) for Southwest Gas Holdings, Inc. and Southwest Gas Corporation, in that order. The Notes to the Condensed Consolidated Financial Statements are presented on a combined basis for both entities. All Items other than Part I – Item 1 are combined for the reporting companies.

2

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

PART I - FINANCIAL INFORMATION

ITEM 1. FINANCIAL STATEMENTS

SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(Thousands of dollars, except par value)

(Unaudited)

	March 31, 2021		December 31, 2020
ASSETS
Utility plant:
Gas plant	$	8,479,295	$	8,384,000
Less: accumulated depreciation	(2,453,924)		(2,419,348)
Construction work in progress	215,395		211,429
Net utility plant	6,240,766		6,176,081
Other property and investments	842,672		834,245
Current assets:
Cash and cash equivalents	92,345		83,352
Accounts receivable, net of allowances	479,184		522,172
Accrued utility revenue	50,500		82,400
Income taxes receivable, net	6,523		10,884
Deferred purchased gas costs	238,886		2,053
Prepaid and other current assets	133,466		170,152
Total current assets	1,000,904		871,013
Noncurrent assets:
Goodwill	346,553		345,184
Deferred income taxes	563		455
Deferred charges and other assets	497,187		508,875
Total noncurrent assets	844,303		854,514
Total assets	$	8,928,645	$	8,735,853
CAPITALIZATION AND LIABILITIES
Capitalization:
Common stock, $1 par (authorized - 120,000,000 shares; issued and outstanding - 57,995,563 and 57,192,925 shares)	$	59,625	$	58,823
Additional paid-in capital	1,660,108		1,609,155
Accumulated other comprehensive loss, net	(58,388)		(61,003)
Retained earnings	1,112,377		1,067,978
Total equity	2,773,722		2,674,953
Redeemable noncontrolling interest	205,286		165,716
Long-term debt, less current maturities	2,696,570		2,732,200
Total capitalization	5,675,578		5,572,869
Current liabilities:
Current maturities of long-term debt	67,334		40,433
Short-term debt	310,000		107,000
Accounts payable	182,805		231,301
Customer deposits	67,121		67,920
Income taxes payable, net	19,356		12,556
Accrued general taxes	72,103		48,640
Accrued interest	34,571		20,536
Deferred purchased gas costs	—		54,636
Other current liabilities	282,745		328,945
Total current liabilities	1,036,035		911,967
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	671,574		647,453
Accumulated removal costs	407,000		404,000
Other deferred credits and other long-term liabilities	1,138,458		1,199,564
Total deferred income taxes and other credits	2,217,032		2,251,017
Total capitalization and liabilities	$	8,928,645	$	8,735,853

The accompanying notes are an integral part of these statements.

3

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(In thousands, except per share amounts)

(Unaudited)

	Three Months Ended March 31,				Twelve Months Ended March 31,
	2021		2020		2021		2020
Operating revenues:
Gas operating revenues	$	521,932	$	502,827	$	1,369,690	$	1,351,089
Utility infrastructure services revenues	363,975		333,493		1,978,770		1,771,609
Total operating revenues	885,907		836,320		3,348,460		3,122,698
Operating expenses:
Net cost of gas sold	156,021		160,821		338,037		353,381
Operations and maintenance	106,690		103,781		411,025		421,686
Depreciation and amortization	93,442		87,653		337,816		313,351
Taxes other than income taxes	20,687		16,378		67,769		62,500
Utility infrastructure services expenses	335,614		319,314		1,745,729		1,592,076
Total operating expenses	712,454		687,947		2,900,376		2,742,994
Operating income	173,453		148,373		448,084		379,704
Other income and (expenses):
Net interest deductions	(23,964)		(28,380)		(107,061)		(111,209)
Other income (deductions)	448		(20,770)		14,429		(17,524)
Total other income and (expenses)	(23,516)		(49,150)		(92,632)		(128,733)
Income before income taxes	149,937		99,223		355,452		250,971
Income tax expense	31,092		26,218		70,627		56,703
Net income	118,845		73,005		284,825		194,268
Net income attributable to noncontrolling interest	1,552		463		7,750		2,599
Net income attributable to Southwest Gas Holdings, Inc.	$	117,293	$	72,542	$	277,075	$	191,669
Earnings per share:
Basic	$	2.04	$	1.31	$	4.90	$	3.50
Diluted	$	2.03	$	1.31	$	4.89	$	3.50
Weighted average shares:
Basic	57,600		55,310		56,564		54,726
Diluted	57,679		55,363		56,649		54,792

The accompanying notes are an integral part of these statements.

4

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(Thousands of dollars)

(Unaudited)

	Three Months Ended March 31,				Twelve Months Ended March 31,
	2021		2020		2021		2020
Net income	$	118,845	$	73,005	$	284,825	$	194,268
Other comprehensive income (loss), net of tax
Defined benefit pension plans:
Net actuarial loss	—		—		(43,730)		(54,026)
Amortization of prior service cost	182		220		840		945
Amortization of net actuarial loss	8,474		7,188		30,037		20,513
Prior service cost	—		—		—		(1,426)
Regulatory adjustment	(7,277)		(6,380)		4,753		25,760
Net defined benefit pension plans	1,379		1,028		(8,100)		(8,234)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	413		636		2,244		2,542
Net forward-starting interest rate swaps	413		636		2,244		2,542
Foreign currency translation adjustments	823		(4,005)		6,541		(2,758)
Total other comprehensive income (loss), net of tax	2,615		(2,341)		685		(8,450)
Comprehensive income	121,460		70,664		285,510		185,818
Comprehensive income attributable to noncontrolling interest	1,552		463		7,750		2,599
Comprehensive income attributable to Southwest Gas Holdings, Inc.	$	119,908	$	70,201	$	277,760	$	183,219

The accompanying notes are an integral part of these statements.

5

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(Thousands of dollars)

(Unaudited)

	Three Months Ended March 31,				Twelve Months Ended March 31,
	2021		2020		2021		2020
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	118,845	$	73,005	$	284,825	$	194,268
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	93,442		87,653		337,816		313,351
Deferred income taxes	23,326		25,309		48,734		54,548
Changes in current assets and liabilities:
Accounts receivable, net of allowances	42,892		45,837		(51,717)		7,154
Accrued utility revenue	31,900		31,000		(2,400)		(1,100)
Deferred purchased gas costs	(291,469)		10,155		(265,385)		19,527
Accounts payable	(41,147)		(60,723)		11,882		(49,945)
Accrued taxes	34,636		30,377		19,430		10,220
Other current assets and liabilities	(5,255)		76,453		25,719		102,742
Gains on sale of equipment	(1,509)		(28)		(3,329)		(5,268)
Changes in undistributed stock compensation	3,658		2,816		7,956		6,524
Equity AFUDC	(981)		(1,061)		(4,644)		(4,262)
Changes in deferred charges and other assets	(10,379)		6,495		(49,465)		1,772
Changes in other liabilities and deferred credits	(50,416)		(55,722)		(57,365)		(65,704)
Net cash provided by (used in) operating activities	(52,457)		271,566		302,057		583,827
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(152,709)		(210,655)		(767,159)		(938,141)
Acquisition of businesses, net of cash acquired	—		—		—		(47,638)
Changes in customer advances	4,286		5,434		12,885		21,357
Other	3,563		4,430		8,136		19,321
Net cash used in investing activities	(144,860)		(200,791)		(746,138)		(945,101)
CASH FLOW FROM FINANCING ACTIVITIES:
Issuance of common stock, net	48,990		3,148		185,087		135,215
Dividends paid	(32,619)		(30,006)		(128,117)		(118,531)
Issuance of long-term debt, net	10,659		99,978		573,058		601,908
Retirement of long-term debt	(21,228)		(75,168)		(302,466)		(257,797)
Change in short-term debt	203,000		(54,000)		153,000		(31,000)
Withholding remittance - share-based compensation	(1,242)		(2,736)		(1,242)		(2,756)
Other	(1,353)		(250)		(4,505)		(1,615)
Net cash provided by (used in) financing activities	206,207		(59,034)		474,815		325,424
Effects of currency translation on cash and cash equivalents	103		(315)		646		(222)
Change in cash and cash equivalents	8,993		11,426		31,380		(36,072)
Cash and cash equivalents at beginning of period	83,352		49,539		60,965		97,037
Cash and cash equivalents at end of period	$	92,345	$	60,965	$	92,345	$	60,965
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	$	8,303	$	13,073	$	100,412	$	99,481
Income taxes paid (received), net	$	1,651	$	(20,064)	$	10,764	$	(17,766)

The accompanying notes are an integral part of these statements.

6

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS HOLDINGS, INC. AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY

(In thousands, except per share amounts)

(Unaudited)

			Three Months Ended March 31,
			2021		2020
Common stock shares
	Beginning balances		57,193		55,007
		Common stock issuances	802		119
	Ending balances		57,995		55,126
Common stock amount
	Beginning balances		$	58,823	$	56,637
		Common stock issuances	802		119
	Ending balances		59,625		56,756
Additional paid-in capital
	Beginning balances		1,609,155		1,466,937
		Common stock issuances	50,953		3,474
	Ending balances		1,660,108		1,470,411
Accumulated other comprehensive loss
	Beginning balances		(61,003)		(56,732)
		Foreign currency exchange translation adjustment	823		(4,005)
		Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax	1,379		1,028
		FSIRS amounts reclassified to net income, net of tax	413		636
	Ending balances		(58,388)		(59,073)
Retained earnings
	Beginning balances		1,067,978		1,039,072
		Net income	117,293		72,542
		Dividends declared	(34,876)		(31,813)
		Redemption value adjustments	(38,018)		—
	Ending balances		1,112,377		1,079,801
Total equity ending balances			$	2,773,722	$	2,547,895
Dividends declared per common share			$	0.595	$	0.57

The accompanying notes are an integral part of these statements.

7

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS CORPORATION AND SUBSIDIARIES

CONDENSED CONSOLIDATED BALANCE SHEETS

(Thousands of dollars)

(Unaudited)

	March 31, 2021		December 31, 2020
ASSETS
Utility plant:
Gas plant	$	8,479,295	$	8,384,000
Less: accumulated depreciation	(2,453,924)		(2,419,348)
Construction work in progress	215,395		211,429
Net utility plant	6,240,766		6,176,081
Other property and investments	146,338		143,611
Current assets:
Cash and cash equivalents	49,795		41,070
Accounts receivable, net of allowance	174,492		146,861
Accrued utility revenue	50,500		82,400
Income taxes receivable, net	—		11,155
Deferred purchased gas costs	238,886		2,053
Prepaid and other current assets	118,397		152,748
Total current assets	632,070		436,287
Noncurrent assets:
Goodwill	10,095		10,095
Deferred charges and other assets	481,184		490,562
Total noncurrent assets	491,279		500,657
Total assets	$	7,510,453	$	7,256,636
CAPITALIZATION AND LIABILITIES
Capitalization:
Common stock	$	49,112	$	49,112
Additional paid-in capital	1,458,344		1,410,345
Accumulated other comprehensive loss, net	(59,343)		(61,135)
Retained earnings	926,011		835,146
Total equity	2,374,124		2,233,468
Long-term debt, less current maturities	2,413,588		2,438,206
Total capitalization	4,787,712		4,671,674
Current liabilities:
Current maturities of long-term debt	25,000		—
Short-term debt	267,000		57,000
Accounts payable	117,471		161,646
Customer deposits	67,121		67,920
Income taxes payable	7,232		—
Accrued general taxes	72,103		48,640
Accrued interest	34,532		20,495
Deferred purchased gas costs	—		54,636
Payable to parent	90		142
Other current liabilities	141,167		146,046
Total current liabilities	731,716		556,525
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	596,617		581,100
Accumulated removal costs	407,000		404,000
Other deferred credits and other long-term liabilities	987,408		1,043,337
Total deferred income taxes and other credits	1,991,025		2,028,437
Total capitalization and liabilities	$	7,510,453	$	7,256,636

The accompanying notes are an integral part of these statements.

8

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS CORPORATION AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF INCOME

(Thousands of dollars)

(Unaudited)

	Three Months Ended March 31,				Twelve Months Ended March 31,
	2021		2020		2021		2020
Gas operating revenues	$	521,932	$	502,827	$	1,369,690	$	1,351,089
Operating expenses:
Net cost of gas sold	156,021		160,821		338,037		353,381
Operations and maintenance	106,135		103,088		409,429		419,720
Depreciation and amortization	68,698		64,725		239,268		222,733
Taxes other than income taxes	20,687		16,378		67,769		62,500
Total operating expenses	351,541		345,012		1,054,503		1,058,334
Operating income	170,391		157,815		315,187		292,755
Other income and (expenses):
Net interest deductions	(22,166)		(25,058)		(98,256)		(96,985)
Other income (deductions)	550		(20,536)		14,496		(16,965)
Total other income and (expenses)	(21,616)		(45,594)		(83,760)		(113,950)
Income before income taxes	148,775		112,221		231,427		178,805
Income tax expense	30,060		28,622		37,193		35,424
Net income	$	118,715	$	83,599	$	194,234	$	143,381

The accompanying notes are an integral part of these statements.

9

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS CORPORATION AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME

(Thousands of dollars)

(Unaudited)

	Three Months Ended March 31,				Twelve Months Ended March 31,
	2021		2020		2021		2020
Net income	$	118,715	$	83,599	$	194,234	$	143,381
Other comprehensive income (loss), net of tax
Defined benefit pension plans:
Net actuarial loss	—		—		(43,730)		(54,026)
Amortization of prior service cost	182		220		840		945
Prior service cost	—		—		—		(1,426)
Amortization of net actuarial loss	8,474		7,188		30,037		20,513
Regulatory adjustment	(7,277)		(6,380)		4,753		25,760
Net defined benefit pension plans	1,379		1,028		(8,100)		(8,234)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	413		636		2,244		2,542
Net forward-starting interest rate swaps	413		636		2,244		2,542
Total other comprehensive income (loss), net of tax	1,792		1,664		(5,856)		(5,692)
Comprehensive income	$	120,507	$	85,263	$	188,378	$	137,689

The accompanying notes are an integral part of these statements.

10

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS CORPORATION AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS

(Thousands of dollars)

(Unaudited)

	Three Months Ended March 31,				Twelve Months Ended March 31,
	2021		2020		2021		2020
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$	118,715	$	83,599	$	194,234	$	143,381
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	68,698		64,725		239,268		222,733
Deferred income taxes	14,952		7,707		52,242		15,118
Changes in current assets and liabilities:
Accounts receivable, net of allowance	(27,631)		1,975		(25,673)		21,652
Accrued utility revenue	31,900		31,000		(2,400)		(1,100)
Deferred purchased gas costs	(291,469)		10,155		(265,385)		19,527
Accounts payable	(33,076)		(41,899)		18,441		(29,798)
Accrued taxes	41,851		53,335		(13,011)		33,526
Other current assets and liabilities	41,018		99,257		(9,694)		106,803
Changes in undistributed stock compensation	2,908		2,496		5,706		5,045
Equity AFUDC	(981)		(1,061)		(4,644)		(4,262)
Changes in deferred charges and other assets	(13,535)		3,658		(61,484)		(9,871)
Changes in other liabilities and deferred credits	(48,782)		(55,910)		(58,008)		(66,294)
Net cash provided by (used in) operating activities	(95,432)		259,037		69,592		456,460
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(128,544)		(173,353)		(647,407)		(788,465)
Changes in customer advances	4,285		5,433		12,885		21,356
Other	(121)		(31)		681		(48)
Net cash used in investing activities	(124,380)		(167,951)		(633,841)		(767,157)
CASH FLOW FROM FINANCING ACTIVITIES:
Contributions from parent	45,984		50,000		173,906		187,094
Dividends paid	(26,000)		(25,200)		(105,300)		(97,600)
Issuance of long-term debt, net	—		—		446,508		297,222
Retirement of long-term debt	—		—		(125,000)		—
Change in short-term debt	210,000		(97,000)		170,000		(91,000)
Withholding remittance - share-based compensation	(1,242)		(2,736)		(1,242)		(2,756)
Other	(205)		(115)		(1,352)		(887)
Net cash provided by (used in) financing activities	228,537		(75,051)		557,520		292,073
Change in cash and cash equivalents	8,725		16,035		(6,729)		(18,624)
Cash and cash equivalents at beginning of period	41,070		40,489		56,524		75,148
Cash and cash equivalents at end of period	$	49,795	$	56,524	$	49,795	$	56,524
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	$	6,952	$	10,204	$	93,474	$	87,277
Income taxes paid (received), net	$	—	$	(22,962)	$	3,359	$	700

The accompanying notes are an integral part of these statements.

11

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SOUTHWEST GAS CORPORATION AND SUBSIDIARIES

CONDENSED CONSOLIDATED STATEMENTS OF EQUITY

(In thousands)

(Unaudited)

			Three Months Ended March 31,
			2021		2020
Common stock shares
	Beginning and ending balances		47,482		47,482
Common stock amount
	Beginning and ending balances		$	49,112	$	49,112
Additional paid-in capital
	Beginning balances		1,410,345		1,229,083
		Share-based compensation	2,015		125
		Contributions from Southwest Gas Holdings, Inc.	45,984		50,000
	Ending balances		1,458,344		1,279,208
Accumulated other comprehensive loss
	Beginning balances		(61,135)		(55,151)
		Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax	1,379		1,028
		FSIRS amounts reclassified to net income, net of tax	413		636
	Ending balances		(59,343)		(53,487)
Retained earnings
	Beginning balances		835,146		782,108
		Net income	118,715		83,599
		Share-based compensation	(350)		(364)
		Dividends declared to Southwest Gas Holdings, Inc.	(27,500)		(25,900)
	Ending balances		926,011		839,443
Total Southwest Gas Corporation equity ending balances			$	2,374,124	$	2,114,276

The accompanying notes are an integral part of these statements.

12

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

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

Nature of Operations. Southwest Gas Holdings, Inc. is a holding company, owning all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas operations” segment) and all of the shares of common stock of Centuri Group, Inc. (“Centuri,” or the “utility infrastructure services” 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 operations segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures.

Centuri is a comprehensive utility infrastructure services enterprise dedicated to delivering a diverse array of solutions to North America’s gas and electric providers. Centuri derives revenue primarily from installation, replacement, repair, and maintenance of energy distribution systems. Centuri operations are generally conducted under the business names of NPL Construction Co. (“NPL”), NPL Canada Ltd. (“NPL Canada”), New England Utility Constructors, Inc. (“Neuco”), and Linetec Services, LLC (“Linetec”). Utility infrastructure services activity is seasonal in most of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern United States (“U.S.”) and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round.

Basis of Presentation. The condensed consolidated financial statements of Southwest Gas Holdings, Inc. and subsidiaries (the “Company”) and Southwest included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. No substantive change has occurred with regard to the Company’s business segments on the whole.

The preparation of the condensed consolidated financial statements 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. In the opinion of management, all adjustments, consisting of normal recurring items and estimates necessary for a fair depiction of results for the interim periods, have been made. In association with the novel Coronavirus (“COVID-19”) pandemic environment, utility operations, and to a large extent, utility infrastructure services, have been deemed “essential services.” Management has considered the impact of the pandemic and adjusted certain estimates, where relevant, used in the preparation of the condensed consolidated financial statements.

These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the 2020 Annual Report to Stockholders, which is incorporated by reference into the 2020 Form 10-K.

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.

13

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

The Company primarily used quoted market prices and other observable market pricing information in valuing cash and cash equivalents, long-term debt outstanding, and assets of the qualified pension plan and postretirement benefit plans required to be recorded and/or disclosed at fair value.

Other Property and Investments. Other property and investments on the Condensed Consolidated Balance Sheets includes:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Southwest Gas Corporation:
Net cash surrender value of COLI policies	$	143,618	$	140,874
Other property	2,720		2,737
Total Southwest Gas Corporation	146,338		143,611
Centuri property, equipment, and intangibles	1,106,855		1,089,414
Centuri accumulated provision for depreciation and amortization	(439,126)		(422,741)
Other property and investments	28,605		23,961
Total Southwest Gas Holdings, Inc.	$	842,672	$	834,245

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. Balances reflect impacts of equity and fixed-income securities underlying the cash surrender values at each reporting date; however, ultimately, only the insurance proceeds are ever actually received, due to management’s intent to hold the policies to maturity.

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 Southwest and the Company include money market fund investments totaling approximately $40,000 for each entity at March 31, 2021 and December 31, 2020, respectively, which fall within Level 2 of the fair value hierarchy, due to the asset valuation methods used by money market funds.

Typical non-cash investing activities include customer advances applied as contributions toward utility construction activity, and capital expenditures that were not paid as of period-end reporting dates, but rather included in accounts payable. Typical activities that represent aspects of both non-cash investing and non-cash financing activities relate to right-of-use assets obtained in exchange for lease liabilities (including, at times, lease terminations and modifications). Amounts related to these collective activities were immaterial for the periods presented herein.

Intercompany Transactions. Centuri recognizes revenues generated from contracts with Southwest (see Note 7 – Segment Information). The accounts receivable balance, revenues, and associated profits are included in the condensed consolidated financial statements of the Company and Southwest and were not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities.

Accounts Receivable, net of 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 no billing due dates customarily extending beyond one month, with customers’ credit worthiness assessed upon account creation by evaluation of other utility service and related payment history. Due to the ongoing COVID-19 pandemic, Southwest continued the moratorium initiated in March 2020 on disconnection of natural gas service for non-payment, but recommenced assessing late fees in Nevada and Arizona in April 2021, with late fees in California expected to recommence in the latter half of 2021. Southwest is actively working with customers experiencing financial hardship by means of flexible payment options. Management continues to monitor expected credit losses in light of the evolving impact of COVID-19. The allowance as of March 31, 2021 reflects the expected impact from the pandemic on balances as of that date, including consideration of customers’ ability to pay currently and once the moratorium on disconnections is lifted.

Utility infrastructure services contracts 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 has not been significantly impacted, nor does it anticipate it will experience significant difficulty in collecting amounts due, as a result of the current environment surrounding COVID-19 given the nature of its customers.

Activity between periods in the allowance for uncollectibles and the balances as of the periods presented within the Company’s and Southwest’s financial statements were not material to the condensed consolidated financial statements overall.

14

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Deferred Purchased Gas Costs. The various regulatory commissions have established procedures to enable Southwest to adjust its 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.

In mid-February 2021, the central U.S. (from south Texas to North Dakota and the eastern Rocky Mountains) experienced extreme cold temperatures, which increased natural gas demand and caused supply issues due to wellhead freeze-offs, power outages, or other adverse operating conditions upstream of Southwest’s distribution systems. These conditions caused daily natural gas prices to reach unprecedented levels. During this time, Southwest secured natural gas supplies, albeit at substantially higher prices, maintaining service to its customers. The incremental cost for these supplies was approximately $250 million, funded using a 364-day $250 million Bank Term Loan executed in March 2021 (see Note 5 – Debt). The incremental gas costs are expected to be collected from customers through the purchased gas adjustment (“PGA”) mechanisms.

Following the extreme weather event, an interstate transmission pipeline company billed Southwest, in addition to customary transmission costs, $65 million for pipeline imbalance charges, allegedly incurred during the period of the pipeline’s critical operation condition. However, Southwest has formally disputed these imbalance charges and believes that no amounts are due to the pipeline. Consequently, Southwest has not recognized this charge. Pipeline transmission costs, including periodic imbalance charges, are components of the cost of gas recovered from customers through the PGA and similar mechanisms.

Prepaid and other current assets. Prepaid and other current assets includes gas pipe materials and operating supplies of $47 million at March 31, 2021 and $50 million at December 31, 2020 (carried at weighted average cost).

Goodwill. Goodwill is assessed as of October 1st each year for impairment, or more frequently, if circumstances indicate an impairment to the carrying value of goodwill may have occurred. Management of the Company and Southwest considered its reporting units and segments and determined that its segments and reporting units remain consistent between periods presented below, and that no change was necessary with regard to the level at which goodwill is assessed for impairment. Since December 31, 2020, management also qualitatively assessed whether events during the first three months of 2021 may have resulted in conditions whereby the carrying value of goodwill was higher than its fair value, which if the case, could be an indication of a permanent impairment. Through this assessment, no such condition was believed to have existed and therefore, no impairment was deemed to have occurred. Goodwill on Southwest’s and the Company’s Condensed Consolidated Balance Sheets includes:

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Total Company
December 31, 2020	$	10,095	$	335,089	$	345,184
Foreign currency translation adjustment	—		1,369		1,369
March 31, 2021	$	10,095	$	336,458	$	346,553

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 amounts payable under regulatory mechanisms, customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities. Other current liabilities for the Company includes $34.5 million and $32.6 million of dividends declared, as well as $37 million and $25.2 million of accrued property taxes, as of March 31, 2021 and December 31, 2020, respectively.

15

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

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

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Southwest Gas Corporation - natural gas operations segment:
Change in COLI policies	$	2,700	$	(15,500)	$	27,400	$	(5,700)
Interest income	716		1,388		3,343		6,147
Equity AFUDC	981		1,061		4,644		4,262
Other components of net periodic benefit cost	(3,505)		(5,005)		(18,522)		(16,299)
Miscellaneous income and (expense)	(342)		(2,480)		(2,369)		(5,375)
Southwest Gas Corporation - total other income (deductions)	550		(20,536)		14,496		(16,965)
Utility infrastructure services segment:
Foreign transaction gain (loss)	(3)		(10)		(9)		5
Miscellaneous income and (expense)	(99)		(232)		(58)		(656)
Centuri - total other income (deductions)	(102)		(242)		(67)		(651)
Corporate and administrative	—		8		—		92
Consolidated Southwest Gas Holdings, Inc. - total other income (deductions)	$	448	$	(20,770)	$	14,429	$	(17,524)

Included in the table above is the change in cash surrender values of COLI policies (including net death benefits recognized). Current tax regulations provide for tax-free treatment of life insurance (death benefit) proceeds. Therefore, changes in the cash surrender values of COLI policies, as they progress towards the ultimate death benefits, are also recorded without tax consequences. Refer to Other Property and Investments above and also to Note 2 – Components of Net Periodic Benefit Cost.

Redeemable Noncontrolling Interest. 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.

Significant changes in the value of the redeemable noncontrolling interest, above a floor established at the acquisition 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 redeemable noncontrolling interest increased by approximately $38 million during the first quarter of 2021. Adjustment to the redemption value also impacts retained earnings, as reflected in the Company’s Condensed Consolidated Statement of Equity, but does not impact net income. The following depicts the change to the balance of the redeemable noncontrolling interest:

(Thousands of dollars):	Redeemable Noncontrolling Interest
Balance, December 31, 2020	$	165,716
Net income attributable to redeemable noncontrolling interest	1,552
Redemption value adjustment	38,018
Balance, March 31, 2021	$	205,286

16

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Earnings Per Share. Basic earnings per share (“EPS”) in each period of this report were calculated by dividing net income 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). 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:

	Three Months Ended March 31,		Twelve Months Ended March 31,
(In thousands)	2021	2020	2021	2020
Weighted average basic shares	57,600	55,310	56,564	54,726
Effect of dilutive securities:
Management Incentive Plan shares	—	—	—	9
Restricted stock units (1)	79	53	85	57
Weighted average diluted shares	57,679	55,363	56,649	54,792

(1) The number of securities included 75,000 and 50,000 performance shares during the three months ending March 31, 2021 and 2020, and 76,000 and 48,000 performance shares during the twelve months ending March 31, 2021 and 2020, respectively, the total of which was derived by assuming that target performance will be achieved during the relevant performance period.

Recent Accounting Standards Updates.

Accounting pronouncements adopted in 2021:

In December 2019, the Financial Accounting Standards Board (the “FASB”) issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” The update simplifies the accounting for income taxes by removing certain exceptions to the general principles, as well as improving consistent application in Topic 740 by clarifying and amending existing guidance. The Company and Southwest adopted the update in the first quarter of 2021, the impact of which was not material to the condensed consolidated financial statements of the Company or Southwest.

Recently issued accounting pronouncements that will be effective after 2021:

In March 2020, the FASB issued 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 Topic 848) to replace a reference rate affected by such reform. The update applies only to contracts and hedging relationships that reference the London Interbank Offered Rate (“LIBOR”) or another 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. Management will 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 5 – 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 update is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years; early adoption is permitted. Management is evaluating what impacts, if any, this update might have on the Company’s consolidated financial statements and disclosures.

17

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Note 2 – Components of Net Periodic Benefit Cost

Southwest has a noncontributory qualified retirement plan with defined benefits covering substantially all employees and a separate unfunded supplemental retirement plan (“SERP”) which is limited to officers. Southwest also provides postretirement benefits other than pensions (“PBOP”) to its qualified retirees for health care, dental, and life insurance.

The service cost component of net periodic benefit costs included in the table below is a component of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of service cost 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 utility plant, and deferred charges and other assets for both the Company and Southwest. The other components of net periodic benefit cost are reflected in Other income (deductions) on the Condensed Consolidated Statements of Income of each entity.

	Qualified Retirement Plan
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	10,290	$	8,574	$	36,015	$	27,972
Interest cost	10,108		11,388		44,275		48,142
Expected return on plan assets	(18,088)		(16,324)		(67,060)		(61,507)
Amortization of net actuarial loss	10,489		9,007		37,507		25,774
Net periodic benefit cost	$	12,799	$	12,645	$	50,737	$	40,381
	SERP
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	131	$	98	$	422	$	298
Interest cost	358		401		1,561		1,721
Amortization of net actuarial loss	660		451		2,014		1,216
Net periodic benefit cost	$	1,149	$	950	$	3,997	$	3,235
	PBOP
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	423	$	396	$	1,608	$	1,353
Interest cost	548		645		2,485		2,929
Expected return on plan assets	(810)		(852)		(3,366)		(3,219)
Amortization of prior service costs	240		289		1,106		1,243
Net periodic benefit cost	$	401	$	478	$	1,833	$	2,306

18

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Note 3 – Revenue

The following information about the Company’s revenues is presented by segment. Southwest encompasses the natural gas operations segment and Centuri encompasses the utility infrastructure services segment.

Natural Gas Operations Segment:

Gas operating revenues on the Condensed Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below, disaggregated by customer type, and various categories of revenue:

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Residential	$	403,143	$	378,555	$	983,108	$	934,115
Small commercial	81,398		82,463		220,476		241,970
Large commercial	12,673		12,667		44,639		47,640
Industrial/other	13,770		6,702		33,310		22,298
Transportation	24,536		24,406		88,345		91,884
Revenue from contracts with customers	535,520		504,793		1,369,878		1,337,907
Alternative revenue program revenues (deferrals)	(16,373)		(3,765)		(468)		5,668
Other revenues (1)	2,785		1,799		280		7,514
Total Gas operating revenues	$	521,932	$	502,827	$	1,369,690	$	1,351,089

(1) 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 customer rates expected to be returned to customers in future periods. Late fees and certain other fees were reduced, for the three- and twelve-month periods ended March 31, 2021, due to a moratorium on late fees and disconnection for nonpayment during the COVID-19 pandemic.

Utility Infrastructure Services Segment:

The following tables display Centuri’s revenue, reflected as Utility infrastructure services revenues on the Condensed Consolidated Statements of Income of the Company, representing revenue from contracts with customers disaggregated by service and contract types:

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Service Types:
Gas infrastructure services	$	221,837	$	217,709	$	1,265,288	$	1,258,790
Electric power infrastructure services	93,961		72,320		433,467		267,736
Other	48,177		43,464		280,015		245,083
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Contract Types:
Master services agreement	$	293,680	$	263,545	$	1,520,144	$	1,411,267
Bid contract	70,295		69,948		458,626		360,342
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609
Unit price contracts	$	234,449	$	243,136	$	1,347,953	$	1,387,706
Fixed price contracts	34,594		27,545		164,750		101,931
Time and materials contracts	94,932		62,812		466,067		281,972
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609

19

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract asset), which are both included within Accounts receivable, net of allowances, as well as amounts billed in excess of revenue earned on contracts (contract liability), which are included in Other current liabilities as of March 31, 2021 and December 31, 2020 on the Company’s Condensed Consolidated Balance Sheets:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Contracts receivable, net	$	197,357	$	278,316
Revenue earned on contracts in progress in excess of billings	107,336		96,996
Amounts billed in excess of revenue earned on contracts	5,985		4,507

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 for billing at the reporting date. These contract assets are transferred to contracts receivable when the rights become unconditional. 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, 2020 to March 31, 2021 is due to revenue recognized of $4.5 million that was included in this item as of January 1, 2021, after which time it became earned and the balance was reduced, and to increases due to cash 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 uses the practical expedient applicable to such contracts and does not consider/compute an interest component based on the time value of money. Further, because of the short duration of these contracts, Centuri 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 March 31, 2021, Centuri had 18 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 March 31, 2021 was $48.7 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 are provided by the customer.

Utility infrastructure services contracts receivable consists of the following:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Billed on completed contracts and contracts in progress	$	193,042	$	273,778
Other receivables	5,789		6,692
Contracts receivable, gross	198,831		280,470
Allowance for doubtful accounts	(1,474)		(2,154)
Contracts receivable, net	$	197,357	$	278,316

20

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Note 4 – Common Stock

Only 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 stock awards to be issued in shares of Southwest Gas Holdings, Inc.

On May 8, 2019, the Company filed with the SEC an automatic shelf registration statement on Form S-3 (File No. 333-231297), which became effective upon filing, for the offer and sale of up to $300 million of common stock from time to time in at-the-market offerings under the prospectus included therein and in accordance with the Sales Agency Agreement, dated May 8, 2019, between the Company and BNY Mellon Capital Markets, LLC (the “Equity Shelf Program”). The following table provides the activity under the Equity Shelf Program for the three-month and life-to-date periods ended March 31, 2021:

	Three Months Ended		Life-To-Date Ended
	March 31, 2021
Gross proceeds	$	46,448,484	$	299,999,974
Less: agent commissions	(464,485)		(3,000,000)
Net proceeds	$	45,983,999	$	296,999,974
Number of shares sold	705,957		4,102,414
Weighted average price per share	$	65.80	$	73.13

During the quarter ended March 31, 2021, the Company sold essentially all of the remaining common stock available for sale 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.

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 for the offer and sale of up to $500 million of common stock from time to time in a new at-the-market offering program. The shares will be issued pursuant to the Company’s automatic shelf registration statement on Form S-3 (File No. 333-251074), which became effective upon filing with the SEC on December 2, 2020.

During the three months ended March 31, 2021, the Company issued approximately 47,000 shares of common stock through the Restricted Stock/Unit Plan and Omnibus Incentive Plan.

Additionally, during the three months ended March 31, 2021, the Company issued 49,500 shares of common stock through the Dividend Reinvestment and Stock Purchase Plan, raising approximately $3.1 million.

21

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Note 5 – Debt

Long-Term Debt

Long-term debt is recognized in the Company’s and Southwest’s Condensed Consolidated Balance Sheets generally at the carrying value of the obligations outstanding. Details surrounding the fair value, as described in Note 1 – Background, Organization, and Summary of Significant Accounting Policies, and individual carrying values of instruments are provided in the table that follows.

	March 31, 2021				December 31, 2020
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
(Thousands of dollars)
Southwest Gas Corporation:
Debentures:
Notes, 6.1%, due 2041	$	125,000	$	160,651	$	125,000	$	174,858
Notes, 3.875%, due 2022	250,000		256,693		250,000		258,825
Notes, 4.875%, due 2043	250,000		288,500		250,000		317,190
Notes, 3.8%, due 2046	300,000		306,261		300,000		347,046
Notes, 3.7%, due 2028	300,000		324,069		300,000		344,553
Notes, 4.15%, due 2049	300,000		324,183		300,000		370,278
Notes, 2.2%, due 2030	450,000		438,912		450,000		474,552
8% Series, due 2026	75,000		95,894		75,000		99,723
Medium-term notes, 7.78% series, due 2022	25,000		26,201		25,000		26,663
Medium-term notes, 7.92% series, due 2027	25,000		32,138		25,000		33,802
Medium-term notes, 6.76% series, due 2027	7,500		9,127		7,500		9,613
Unamortized discount and debt issuance costs	(17,501)				(17,822)
	2,089,999				2,089,678
Revolving credit facility and commercial paper	150,000		150,000		150,000		150,000
Industrial development revenue bonds:
Variable-rate 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	(1,411)				(1,472)
	198,589				198,528
Less: current maturities	(25,000)				—
Long-term debt, less current maturities - Southwest Gas Corporation	$	2,413,588			$	2,438,206
Centuri:
Centuri term loan facility	$	222,668	$	225,269	$	226,648	$	230,824
Unamortized debt issuance costs	(750)				(820)
	221,918				225,828
Centuri secured revolving credit facility	26,163		26,180		26,626		26,645
Centuri other debt obligations	77,235		78,378		81,973		84,246
Less: current maturities	(42,334)				(40,433)
Long-term debt, less current maturities - Centuri	$	282,982			$	293,994
Consolidated Southwest Gas Holdings, Inc.:
Southwest Gas Corporation long-term debt	$	2,438,588			$	2,438,206
Centuri long-term debt	325,316				334,427
Less: current maturities	(67,334)				(40,433)
Long-term debt, less current maturities - Southwest Gas Holdings, Inc.	$	2,696,570			$	2,732,200

22

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

The fair values of Southwest's revolving credit facility and IDRBs are categorized as Level 1 based on the FASB’s fair value hierarchy, due to Southwest’s ability to access similar debt arrangements at measurement dates with comparable terms, including variable/market rates. The fair values of Southwest’s debentures (which include senior and medium-term 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. Centuri's secured revolving credit and term loan facility and other debt obligations (not actively traded) are categorized as Level 3; fair values were based on a conventional discounted cash flow methodology utilizing current market pricing yield curves.

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 LIBOR or an “alternate base rate,” plus in each case an applicable margin that is determined based on Southwest’s senior unsecured debt rating. At March 31, 2021, the applicable margin is 1% for loans bearing interest with reference to LIBOR and 0% for loans bearing interest with reference to the alternative base rate. At March 31, 2021, $150 million was outstanding on the long-term portion (including $50 million under the commercial paper program, discussed below) of the facility and $17 million of borrowings were outstanding on the short-term portion of this credit facility discussed below.

Southwest has a $50 million commercial paper program. Issuances under the commercial paper program are supported by Southwest’s revolving credit facility and, therefore, do not represent additional borrowing capacity under the credit facility. Borrowings under the commercial paper program are designated as long-term debt. Interest rates for the program are calculated at the then current commercial paper rate. At March 31, 2021, as noted above, $50 million of borrowings were outstanding under the commercial paper program.

Centuri has a $590 million senior secured revolving credit and term loan facility, scheduled to expire in November 2023. The capacity of the line of credit portion of the facility is $325 million; related amounts borrowed and repaid are available to be re-borrowed. The term loan portion of the facility has a limit of approximately $265 million. The $590 million facility is secured by substantially all of Centuri’s assets except those explicitly excluded under the terms of the agreement (including owned real estate and certain certificated vehicles). Centuri’s assets securing the facility at March 31, 2021 totaled $1.3 billion. At March 31, 2021, $249 million in borrowings were outstanding under Centuri’s combined secured revolving credit and term loan facility.

Short-Term Debt

Southwest Gas Holdings, Inc. has a $100 million credit facility that is scheduled to expire in April 2025 and is primarily used for short-term financing needs. There was $43 million outstanding under this credit facility as of March 31, 2021.

Under Southwest’s $400 million credit facility, Southwest had $17 million in short-term borrowings outstanding at March 31, 2021.

In March 2021, Southwest issued a $250 million Term Loan that matures March 22, 2022. The proceeds were 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. (see Deferred Purchased Gas Costs in Note 1 – Background, Organization, and Summary of Significant Accounting Policies). Interest rates for the term loan are calculated at either LIBOR 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 LIBOR and 0.000% for loans bearing interest with reference to an alternate base rate. The effective interest rate was 0.77% at March 31, 2021. The 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

LIBOR is scheduled to be discontinued as a benchmark or reference rate after 2021. In order to mitigate the impact of a discontinuance on the Company’s and Southwest’s financial condition and results of operations, management will monitor developments and work with lenders to determine the appropriate replacement/alternative reference rate for variable rate debt. At this time the Company and Southwest can provide no assurances as to the impact a LIBOR discontinuance will have on their financial condition or results of operations. Any alternative rate may be less predictable or less attractive than LIBOR.

23

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Note 6 – Other Comprehensive Income and Accumulated Other Comprehensive Income

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

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

	Three Months Ended March 31, 2021						Three Months Ended March 31, 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
Defined benefit pension plans:
Amortization of prior service cost	$	240	$	(58)	$	182	$	289	$	(69)	$	220
Amortization of net actuarial (gain)/loss	11,149		(2,675)		8,474		9,458		(2,270)		7,188
Regulatory adjustment	(9,575)		2,298		(7,277)		(8,395)		2,015		(6,380)
Pension plans other comprehensive income (loss)	1,814		(435)		1,379		1,352		(324)		1,028
FSIRS (designated hedging activities):
Amounts reclassified into net income	544		(131)		413		837		(201)		636
FSIRS other comprehensive income (loss)	544		(131)		413		837		(201)		636
Total other comprehensive income (loss) - Southwest Gas Corporation	2,358		(566)		1,792		2,189		(525)		1,664
Foreign currency translation adjustments:
Translation adjustments	823		—		823		(4,005)		—		(4,005)
Foreign currency other comprehensive income (loss)	823		—		823		(4,005)		—		(4,005)
Total other comprehensive income (loss) - Southwest Gas Holdings, Inc.	$	3,181	$	(566)	$	2,615	$	(1,816)	$	(525)	$	(2,341)

	Twelve Months Ended March 31, 2021						Twelve Months Ended March 31, 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
Defined benefit pension plans:
Net actuarial gain/(loss)	$	(57,539)	$	13,809	$	(43,730)	$	(71,087)	$	17,061	$	(54,026)
Amortization of prior service cost	1,106		(266)		840		1,243		(298)		945
Amortization of net actuarial (gain)/loss	39,521		(9,484)		30,037		26,990		(6,477)		20,513
Prior service cost	—		—		—		(1,878)		452		(1,426)
Regulatory adjustment	6,255		(1,502)		4,753		33,896		(8,136)		25,760
Pension plans other comprehensive income (loss)	(10,657)		2,557		(8,100)		(10,836)		2,602		(8,234)
FSIRS (designated hedging activities):
Amounts reclassified into net income	2,954		(710)		2,244		3,345		(803)		2,542
FSIRS other comprehensive income (loss)	2,954		(710)		2,244		3,345		(803)		2,542
Total other comprehensive income (loss) - Southwest Gas Corporation	(7,703)		1,847		(5,856)		(7,491)		1,799		(5,692)
Foreign currency translation adjustments:
Translation adjustments	6,541		—		6,541		(2,758)		—		(2,758)
Foreign currency other comprehensive income (loss)	6,541		—		6,541		(2,758)		—		(2,758)
Total other comprehensive income (loss) - Southwest Gas Holdings, Inc.	$	(1,162)	$	1,847	$	685	$	(10,249)	$	1,799	$	(8,450)

(1)Tax amounts are calculated using a 24% rate. The Company has elected to indefinitely reinvest the earnings of Centuri’s Canadian subsidiaries in Canada, thus precluding 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 reported in Other comprehensive income (loss).

Approximately $1.7 million of realized losses (net of tax) related to the remaining balance of Southwest’s previously settled forward-starting interest rate swap (“FSIRS”), included in AOCI at March 31, 2021, will be reclassified into interest expense within the next 12 months as the related interest payments on long-term debt occur.

24

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

The following table represents a rollforward of AOCI, presented on the Company’s Condensed Consolidated Balance Sheets and its Condensed 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, 2020	$	(77,720)	$	18,653	$	(59,067)	$	(2,719)	$	651	$	(2,068)	$	132	$	—	$	132	$	(61,003)
Translation adjustments	—		—		—		—		—		—		823		—		823		823
Other comprehensive income (loss) before reclassifications	—		—		—		—		—		—		823		—		823		823
FSIRS amount reclassified from AOCI (1)	—		—		—		544		(131)		413		—		—		—		413
Amortization of prior service cost (2)	240		(58)		182		—		—		—		—		—		—		182
Amortization of net actuarial loss (2)	11,149		(2,675)		8,474		—		—		—		—		—		—		8,474
Regulatory adjustment (3)	(9,575)		2,298		(7,277)		—		—		—		—		—		—		(7,277)
Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	1,814		(435)		1,379		544		(131)		413		823		—		823		2,615
Ending Balance AOCI March 31, 2021	$	(75,906)	$	18,218	$	(57,688)	$	(2,175)	$	520	$	(1,655)	$	955	$	—	$	955	$	(58,388)

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

(2)These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost 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 Condensed Consolidated Balance Sheets).

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

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

	Defined Benefit Plans						FSIRS
(Thousands of dollars)	Before-Tax		Tax (Expense) Benefit (8)		After-Tax		Before-Tax		Tax (Expense) Benefit (8)		After-Tax		AOCI
Beginning Balance AOCI December 31, 2020	$	(77,720)	$	18,653	$	(59,067)	$	(2,719)	$	651	$	(2,068)	$	(61,135)
FSIRS amount reclassified from AOCI (5)	—		—		—		544		(131)		413		413
Amortization of prior service cost (6)	240		(58)		182		—		—		—		182
Amortization of net actuarial loss (6)	11,149		(2,675)		8,474		—		—		—		8,474
Regulatory adjustment (7)	(9,575)		2,298		(7,277)		—		—		—		(7,277)
Net current period other comprehensive income attributable to Southwest Gas Corporation	1,814		(435)		1,379		544		(131)		413		1,792
Ending Balance AOCI March 31, 2021	$	(75,906)	$	18,218	$	(57,688)	$	(2,175)	$	520	$	(1,655)	$	(59,343)

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

(6)These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details).

(7)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 Southwest’s Condensed Consolidated Balance Sheets).

(8)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:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Net actuarial loss	$	(491,634)	$	(502,783)
Prior service cost	(2,247)		(2,487)
Less: amount recognized in regulatory assets	417,975		427,550
Recognized in AOCI	$	(75,906)	$	(77,720)

25

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Note 7 – Segment Information

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:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Centuri accounts receivable for services provided to Southwest	$	11,344	$	13,956

The Company has two reportable segments: natural gas operations and utility infrastructure services. Southwest has a single reportable segment that is referred to herein as the natural gas operations segment of the Company. In order to reconcile to net income as disclosed in the Condensed 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 the natural gas operations and utility infrastructure services segments is as follows:

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Other		Total
Three Months Ended March 31, 2021
Revenues from external customers	$	521,932	$	339,772	$	—	$	861,704
Intersegment revenues	—		24,203		—		24,203
Total	$	521,932	$	363,975	$	—	$	885,907
Segment net income (loss)	$	118,715	$	(859)	$	(563)	$	117,293
Three Months Ended March 31, 2020
Revenues from external customers	$	502,827	$	300,291	$	—	$	803,118
Intersegment revenues	—		33,202		—		33,202
Total	$	502,827	$	333,493	$	—	$	836,320
Segment net income (loss)	$	83,599	$	(10,204)	$	(853)	$	72,542

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Other		Total
Twelve Months Ended March 31, 2021
Revenues from external customers	$	1,369,690	$	1,852,910	$	—	$	3,222,600
Intersegment revenues	—		125,860		—		125,860
Total	$	1,369,690	$	1,978,770	$	—	$	3,348,460
Segment net income (loss)	$	194,234	$	84,207	$	(1,366)	$	277,075
Twelve Months Ended March 31, 2020
Revenues from external customers	$	1,351,089	$	1,618,354	$	—	$	2,969,443
Intersegment revenues	—		153,255		—		153,255
Total	$	1,351,089	$	1,771,609	$	—	$	3,122,698
Segment net income (loss)	$	143,381	$	50,231	$	(1,943)	$	191,669

26

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

ITEM 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS

Southwest Gas Holdings, Inc. is a holding company that owns all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas operations” segment) and all of the shares of common stock of Centuri Group, Inc. (“Centuri,” or the “utility infrastructure services” segment). Southwest Gas Holdings, Inc. and its subsidiaries are collectively referred to as the “Company.”

Southwest is engaged in the business of purchasing, distributing, and transporting natural gas for customers in portions of Arizona, Nevada, and California. Southwest is the largest distributor of natural gas in Arizona, selling and transporting natural gas in most of central and southern Arizona, including the Phoenix and Tucson metropolitan areas. Southwest is also the largest distributor of natural gas in Nevada, serving the majority of southern Nevada, including the Las Vegas metropolitan area, and portions of northern Nevada. In addition, Southwest distributes and transports natural gas for customers in portions of California, including the Lake Tahoe area and the high desert and mountain areas in San Bernardino County.

As of March 31, 2021, Southwest had 2,133,000 residential, commercial, industrial, and other natural gas customers, of which 1,138,000 customers were located in Arizona, 793,000 in Nevada, and 202,000 in California. Over the past twelve months, first-time meter sets were approximately 37,000, compared to 36,000 for the twelve months ended March 2020. The remaining increase in active customer accounts compared to the March 31, 2020 total of 2,091,000 was primarily due to a management-initiated moratorium on disconnections as a result of the COVID-19 pandemic. As utility service is an essential service to the residents in the states in which Southwest operates, it implemented the moratorium in March 2020 and also ceased charging late fees. Southwest recommenced assessing late fees in Nevada and Arizona in April 2021, with late fees in California expected to recommence in the latter half of 2021. The duration of our moratorium on disconnections for non-payment is currently uncertain. Residential and small commercial customers represented over 99% of the total customer base. During the twelve months ended March 31, 2021, 53% of operating margin (gas operating revenues less the net cost of gas sold) was earned in Arizona, 36% in Nevada, and 11% in California. During this same period, Southwest earned 85% of its operating margin from residential and small commercial customers, 3% from other sales customers, and 12% from transportation customers. While these general patterns are expected to remain materially consistent for the foreseeable future, the continuing COVID-19 pandemic, as discussed further below, could impact these statistics and associated patterns in the short term.

Southwest recognizes operating revenues from the distribution and transportation of natural gas (and related services) to customers. Operating margin is a financial measure defined by management as gas operating revenues less the net cost of gas sold. However, operating margin is not specifically defined in accounting principles generally accepted in the United States (“U.S. GAAP”). Thus, operating margin is considered a non-GAAP measure. Management uses this financial measure because natural gas operating revenues include the net cost of gas sold, which is a tracked cost that is passed through to customers without markup under purchased gas adjustment (“PGA”) mechanisms. Fluctuations in the net cost of gas sold impact revenues on a dollar-for-dollar basis, but do not impact operating margin or operating income. Therefore, management believes operating margin provides investors and other interested parties with useful and relevant information to analyze Southwest’s financial performance in a rate-regulated environment. The principal factors affecting changes in operating margin are general rate relief (including impacts of infrastructure trackers) and customer growth. Commission decisions on the amount and timing of such relief may impact our earnings. Refer to the Summary Operating Results table for a reconciliation of revenues to operating margin, and refer to Rates and Regulatory Proceedings in this Management’s Discussion and Analysis, for details of various rate proceedings.

The demand for natural gas is seasonal, with greater demand in the colder winter months and decreased demand in the warmer summer months. All of Southwest’s service territories have decoupled rate structures (alternative revenue programs), which are designed to eliminate the direct link between volumetric sales and revenue, thereby mitigating the impacts of unusual weather variability and conservation on operating margin, allowing Southwest to pursue energy efficiency initiatives.

Centuri is a comprehensive utility infrastructure services enterprise dedicated to delivering a diverse array of solutions to North America’s gas and electric providers. Centuri derives revenue primarily from installation, replacement, repair, and maintenance of energy distribution systems. Centuri operates in 55 primary locations across 40 states and provinces in the United States (“U.S.”) and Canada. Centuri operates in the U.S., primarily as NPL, Neuco, and Linetec, and in Canada, primarily as NPL Canada.

27

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Utility infrastructure services activity can be impacted by changes in infrastructure replacement programs of utilities, weather, and local and federal regulation (including tax rates and incentives). Utilities continue to implement or modify system integrity management programs to enhance safety pursuant to federal and state mandates. These programs have resulted in multi-year utility system replacement projects throughout the U.S. Generally, Centuri revenues are lowest during the first quarter of the year due to less favorable winter weather conditions. Revenues typically improve as more favorable weather conditions occur during the summer and fall months. In cases of severe weather, such as following a regional storm, Centuri may be engaged to perform restoration activities related to above-ground utility infrastructure. In certain circumstances, such as with large bid contracts (especially those of a longer duration), or unit-price contracts with revenue caps, results may be impacted by differences between costs incurred and those anticipated when the work was originally bid. Work awarded, or failing to be awarded, by individual large customers can significantly impact operating results.

COVID-19 Pandemic

While the novel coronavirus (“COVID-19”) pandemic has been ongoing since the first quarter of 2020, management has remained focused on the impacts to local and U.S. economies, including the breadth of vaccine deployment and level of commerce re-opening. Our utility operations, as essential services, have been ongoing during this time and Southwest has continued to provide services to meet the demand of its customers. Consistent with federal and state guidelines and protocols, Southwest has continued to operate across its territories. Similarly, Centuri has continued nearly all operations from the outset of the pandemic in the U.S., and demand has not significantly diminished. For the duration of the pandemic, the ability to work may nonetheless be impacted by individuals contracting or being exposed to COVID-19, governmental requirements to postpone the full resumption of certain non-essential services in some of the Company’s jurisdictions, or by management imposed restrictions for safety precautions; to date, these factors have not had a significant impact on the Company’s ability to maintain operations. Employees at many offices (including corporate headquarters) continue to work from home on a temporary basis and travel restrictions largely continue. Both segments continue to facilitate administration, communication, and all critical functions, supported by deployed technology. To date, there has not been a significant disruption in the Company’s supply chains, transportation network, or ability to serve customers.

As noted earlier, management continues to have in place a moratorium on natural gas disconnections for non-payment and continues to work with customers experiencing financial hardship through flexible payment arrangements. Management also continues to coordinate with certain governmental and nonprofit entities for customer payment assistance. Management has increased the allowance for uncollectibles; however, neither this nor other measures associated with the moratorium have had a material impact on our financial position overall. See Accounts receivable, net of allowances in Note 1 – Background, Organization, and Summary of Significant Accounting Policies. In the utility infrastructure services segment, a limited number of Centuri customers at the outset of the pandemic delayed some projects, and crews were temporarily reduced; however, most work continued, while following appropriate government protocols. Some crew reductions are ongoing in specific areas; however, the associated revenue impacts have not been significant. Management continues to monitor these circumstances, the future impacts of which are not currently known, such as the impact from business curtailments, weak market conditions, or any restrictions that may limit the fulfillment by Centuri of its contractual obligations.

The extent to which COVID-19 may adversely impact the Company’s business depends on future developments, including the timing of full resumption of commerce across our service territories, the deployment of vaccines and population immunity, the state of local and North American economies, and impacts of these collective conditions on our customers, in addition to other unmitigated effects related to the virus. Management does not currently expect the impact of these conditions to be material to the Company’s liquidity or financial position; however, continued uncertainty of economic and operational impacts means management cannot predict whether the related financial impact in future periods will be different from impacts reflected for the three and twelve months ended March 31, 2021. In anticipation of a redeployment of employees to their normal work locations, management created a multi-phase reintegration plan to safeguard the well-being of our teams. Management will continue to monitor developments by government officials, and those affecting employees, customers, and operations, and will take additional steps as necessary to address impacts from the pandemic. Events and circumstances arising after March 31, 2021, including those resulting from COVID-19, will be reflected in management’s estimates for future periods.

This Management’s Discussion and Analysis (“MD&A”) of Financial Condition and Results of Operations should be read in conjunction with the unaudited condensed consolidated financial statements and notes thereto included in this Quarterly Report on Form 10-Q and the audited financial statements and notes thereto, as well as MD&A, included in the 2020 Annual Report to Stockholders, which is incorporated by reference into the 2020 Form 10-K.

28

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Executive Summary

The items discussed in this Executive Summary are intended to provide an overview of the results of the Company’s and Southwest’s operations. As needed, certain items are covered in greater detail in later sections of MD&A. As reflected in the table below, the natural gas operations segment accounted for an average of 72% of twelve-month-to-date consolidated net income over the past two years. Natural gas sales are seasonal, peaking during the winter months; therefore, results of operations for interim periods are not necessarily indicative of results for a full year.

Summary Operating Results

	Period Ended March 31,
	Three Months				Twelve Months
(In thousands, except per share amounts)	2021		2020		2021		2020
Contribution to net income
Natural gas operations	$	118,715	$	83,599	$	194,234	$	143,381
Utility infrastructure services	(859)		(10,204)		84,207		50,231
Corporate and administrative	(563)		(853)		(1,366)		(1,943)
Net income	$	117,293	$	72,542	$	277,075	$	191,669
Weighted average common shares	57,600		55,310		56,564		54,726
Basic earnings per share
Consolidated	$	2.04	$	1.31	$	4.90	$	3.50
Natural Gas Operations
Reconciliation of Revenue to Operating Margin (Non-GAAP measure)
Gas operating revenues	$	521,932	$	502,827	$	1,369,690	$	1,351,089
Less: Net cost of gas sold	156,021		160,821		338,037		353,381
Operating margin	$	365,911	$	342,006	$	1,031,653	$	997,708

1st Quarter 2021 Overview

Natural gas operations highlights include the following:

•37,000 first-time meters sets (1.8% growth rate) occurred over the past 12 months

•Operating margin increased $24 million

•Company-Owned Life Insurance (“COLI”) income was $2.7 million in the current quarter versus a loss of $15.5 million in the prior-year quarter

•Issued $250 million term loan due March 2022 to fund incremental gas costs

•California rate case finalized

Utility infrastructure services highlights include the following:

•Utility infrastructure services revenues increased $30 million, or 9.1%

•Supported customers with restoration services following winter freeze event ($9 million of incremental revenue)

•Utility infrastructure services expenses increased $16 million, or 5.1%

•Realized $1.5 million in gains on sale of equipment

Southwest Gas Holdings highlights include the following:

•Increased the quarterly dividend from $0.570 to $0.595 per share effective with the June 2021 payment

•Received net proceeds of $46 million through equity shelf program issuances

29

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Results of Natural Gas Operations

Quarterly Analysis

	Three Months Ended March 31,
(Thousands of dollars)	2021		2020
Gas operating revenues	$	521,932	$	502,827
Net cost of gas sold	156,021		160,821
Operating margin	365,911		342,006
Operations and maintenance expense	106,135		103,088
Depreciation and amortization	68,698		64,725
Taxes other than income taxes	20,687		16,378
Operating income	170,391		157,815
Other income (deductions)	550		(20,536)
Net interest deductions	22,166		25,058
Income before income taxes	148,775		112,221
Income tax expense	30,060		28,622
Contribution to consolidated net income	$	118,715	$	83,599

Improvements from natural gas operations to consolidated net income of $35 million occurred between the first quarters of 2021 and 2020. The improvement was primarily due to increases in Operating Margin and Other income.

Operating margin increased $24 million. Approximately $6 million of incremental margin was attributable to customer growth from 37,000 first-time meter sets during the last twelve months, while rate relief added $18 million of margin. Offsetting these increases were impacts from the temporary moratorium on late fees initiated by Southwest in March 2020 ($2.6 million), in addition to lower connection/re-connection charges, as a result of the COVID-19 pandemic. Amounts returned to and collected from customers associated with regulatory account balances, as well as differences in miscellaneous revenue and margin from customers outside the decoupling mechanisms, also impacted the variance between periods.

Operations and maintenance expense increased $3 million, or 3%, between quarters primarily due to an increase in the service-related component of employee pension cost and other benefits, increased expenditures for pipeline damage prevention programs, and increased legal claim-related costs, offset by lower training and travel costs as a result of the current COVID-19 environment.

Depreciation and amortization expense increased $4 million, or 6%, between quarters, primarily due to a $546 million, or 7%, increase in average gas plant in service compared to the corresponding quarter a year ago. Amortization of regulatory program balances impacted expense in both periods. The increase in gas plant was attributable to pipeline capacity reinforcement work, franchise requirements, scheduled pipe replacement activities, and new infrastructure.

Taxes other than income taxes increased $4.3 million between quarters primarily due to an increase in Arizona property taxes.

Other income improved $21.1 million between quarters primarily due to an increase in income from COLI policies. The current quarter reflects a $2.7 million increase in COLI policy cash surrender values, while the prior-year quarter reflected a $15.5 million decline in COLI policy cash surrender values. These fluctuations primarily result from changes in the values of equity securities associated with the cash surrender values; changes in both quarters were directionally consistent with the broader securities markets. Additionally, the non-service-related components of employee pension and other postretirement benefit costs decreased $1.5 million between periods.

Net interest deductions decreased $2.9 million in the first quarter of 2021, as compared to the prior-year quarter, primarily due to lower carrying costs on PGA balances and amortization of an interest-related regulatory balance in Arizona, as well as lower interest rates associated with variable-rate debt.

Income tax expense in both periods reflects that COLI results are recognized without tax consequences, and also reflects the amortization of excess accumulated deferred income tax (“EADIT”) balances.

30

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Results of Natural Gas Operations

Twelve-Month Analysis

	Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020
Gas operating revenues	$	1,369,690	$	1,351,089
Net cost of gas sold	338,037		353,381
Operating margin	1,031,653		997,708
Operations and maintenance expense	409,429		419,720
Depreciation and amortization	239,268		222,733
Taxes other than income taxes	67,769		62,500
Operating income	315,187		292,755
Other income (deductions)	14,496		(16,965)
Net interest deductions	98,256		96,985
Income before income taxes	231,427		178,805
Income tax expense	37,193		35,424
Contribution to consolidated net income	$	194,234	$	143,381

Contribution to consolidated net income from natural gas operations increased $51 million between the twelve-month periods ended March 2021 and 2020. The increase was primarily due to an increase in Operating margin and Other income.

Operating margin increased $34 million between periods. Customer growth provided $15 million, and combined rate relief provided $24 million of incremental operating margin. The pandemic-period moratorium on late fees ($7.3 million) and lower connection/re-connection charges offset the improvements. Regulatory account balance return and recoveries impacted both periods, in addition to margin from customers outside the decoupling mechanisms.

Operations and maintenance expense decreased $10.3 million, or 2%, between periods primarily due to lower travel and in-person training costs in the current COVID-19 environment and due to other cost saving initiatives by management. These were partially offset by incremental expenditures for pipeline damage prevention programs associated with a growing infrastructure and customer base, and by increases in information technology costs.

Depreciation and amortization expense increased $16.5 million, or 7%, between periods primarily due to a $634 million, or 8%, increase in average gas plant in service since the corresponding period in the prior year, offset by a modest decrease in regulatory amortization.

Taxes other than income taxes increased $5.3 million between periods primarily due to an increase in property taxes in Arizona, and to a lesser extent, in Southwest’s California and Nevada jurisdictions.

Other income increased $31.5 million between the twelve-month periods of 2021 and 2020, primarily due to a current-period $27.4 million increase in COLI policy cash surrender values and recognized death benefits, while the twelve months ended March 31, 2020 reflected a $5.7 million decline. Offsetting these amounts were lower interest earned on regulatory balances and an increase in non-service related components of post-retirement benefit cost.

Net interest deductions increased $1.3 million between periods primarily due to interest associated with the issuance of $450 million of Senior Notes in June 2020, offset by amortization of an interest-related regulatory balance in Arizona and a reduction in interest rates on variable-rate debt.

Income tax expense in both periods reflects that COLI results are recognized without tax consequences, and also reflects the amortization of EADIT balances.

31

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Results of Utility Infrastructure Services

Quarterly Analysis

	Three Months Ended March 31,
(Thousands of dollars)	2021		2020
Utility infrastructure services revenues	$	363,975	$	333,493
Operating expenses:
Utility infrastructure services expenses	335,614		319,314
Depreciation and amortization	24,744		22,928
Operating income (loss)	3,617		(8,749)
Other income (deductions)	(102)		(242)
Net interest deductions	1,622		2,899
Income (loss) before income taxes	1,893		(11,890)
Income tax expense (benefit)	1,200		(2,149)
Net income (loss)	693		(9,741)
Net income attributable to noncontrolling interest	1,552		463
Contribution to consolidated net income attributable to Centuri	$	(859)	$	(10,204)

Utility infrastructure services revenues increased $30.5 million in the first quarter of 2021 when compared to the prior-year quarter, primarily due to incremental electric infrastructure revenues of $21.6 million from expansion of work with existing customers and securing work with new customers. Included in the incremental electric infrastructure revenues during the first quarter of 2021 was $9 million from emergency restoration services performed by Linetec following tornados and ice storms primarily in Texas. The remaining increase in revenue was attributable to favorable weather in several areas and customer scheduling, which allowed bid projects to be completed during an otherwise seasonally slow period.

Utility infrastructure services expenses increased $16.3 million in the first quarter of 2021 when compared to the prior-year quarter, primarily due to costs to complete additional electric and gas infrastructure work. Operating efficiencies improved due to favorable weather conditions and reduced COVID-19 restrictions from the prior year. Additionally, changes in mix of work resulted in lower subcontractor expenses as a percentage of revenues, which contributed to increased operating income. Storm restoration work typically generates a higher profit margin than core infrastructure services, due to improved operating efficiencies related to equipment utilization and absorption of fixed costs. Included in total Utility infrastructure services expenses were general and administrative costs, which increased $3.3 million in 2021 compared to 2020, associated primarily with growth of the business. Gains on sale of equipment in the first quarter of 2021 (reflected as an offset to Utility infrastructure services expenses) were $1.5 million.

Depreciation and amortization expense increased $1.8 million between quarters, attributable to equipment purchased to support the growing business, primarily at Linetec. Depreciation expense, relative to the revenues recorded, was generally consistent between periods.

Net interest deductions decreased $1.3 million between quarters primarily due to lower incremental borrowing rates associated with decreased outstanding borrowings under Centuri’s $590 million secured revolving credit and term loan facility.

32

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Results of Utility Infrastructure Services

Twelve-Month Analysis

	Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020
Utility infrastructure services revenues	$	1,978,770	$	1,771,609
Operating expenses:
Utility infrastructure services expenses	1,745,729		1,592,076
Depreciation and amortization	98,548		90,618
Operating income	134,493		88,915
Other income (deductions)	(67)		(651)
Net interest deductions	7,992		13,716
Income before income taxes	126,434		74,548
Income tax expense	34,477		21,718
Net income	91,957		52,830
Net income attributable to noncontrolling interest	7,750		2,599
Contribution to consolidated net income attributable to Centuri	$	84,207	$	50,231

Utility infrastructure services revenues increased $207.2 million, or 12%, in the current twelve-month period compared to the corresponding period of 2020, primarily due to incremental electric infrastructure revenues of $165.7 million from expansion of work with existing customers and securing work with new customers. Included in the incremental electric infrastructure revenues during the twelve-month period of 2021 was $90.5 million from emergency restoration services performed by Linetec, following hurricane, tornado, and other storm damage to customers’ above-ground utility infrastructure in and around the Gulf Coast and eastern regions of the U.S., as compared to $13.2 million in similar services during the twelve-month period in 2020. Centuri’s revenues derived from storm-related services vary from period to period due to the unpredictable nature of weather-related events. The remaining increase in revenue was attributable to continued growth with existing gas infrastructure customers under master service and bid agreements.

Utility infrastructure services expenses increased $153.7 million between periods, largely due to incremental expenses related to electric infrastructure work of $91.4 million, including costs associated with storm restoration work, as well as costs to complete additional gas and electric infrastructure work. These costs were mitigated by increased productivity and efficiencies in completing electrical infrastructure projects and by lower fuel costs as a percentage of revenues. Included in Utility infrastructure services expenses were general and administrative costs, which increased $26.1 million in the twelve-month period ended March 2021 when compared to the corresponding period ended March 2020, due to higher payroll and operating costs associated with continued growth of the business and higher profit-based incentive compensation costs. Offsetting these increases were lower insurance costs from favorable claims experience under Centuri’s self-insurance programs. Gains on sale of equipment (reflected as an offset to Utility infrastructure services expenses) were $3.3 million and $5.3 million for the twelve-month periods of 2021 and 2020, respectively.

Depreciation and amortization expense increased $7.9 million between the current and prior-year period. The increase was primarily attributable to incremental costs of $6.3 million to support the electric infrastructure work being performed, and to additional property and equipment purchased to support the growing business overall.

Net interest deductions decreased $5.7 million between periods primarily due to lower incremental borrowing rates associated with decreased outstanding borrowings under Centuri’s $590 million secured revolving credit and term loan facility.

The income tax expense increase between periods reflects the increased level of pre-tax earnings.

33

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Rates and Regulatory Proceedings

Southwest is subject to the regulation of the Arizona Corporation Commission (the “ACC”), the Public Utilities Commission of Nevada (the “PUCN”), the California Public Utilities Commission (the “CPUC”), and the Federal Energy Regulatory Commission (the “FERC”).

General Rate Relief and Rate Design

Rates charged to customers vary according to customer class and rate jurisdiction and are set by the individual state and federal regulatory commissions that govern Southwest’s service territories. Southwest makes periodic filings for rate adjustments as the cost of providing service (including the cost of natural gas purchased) changes, and as additional investments in new or replacement pipeline and related facilities are made. Rates are intended to provide for recovery of all commission-approved costs and a reasonable return on investment. The mix of fixed and variable components in rates assigned to various customer classes (rate design) can significantly impact the operating margin actually realized by Southwest. Management has worked with its regulatory commissions in designing rate structures that strive to provide affordable and reliable service to its customers while mitigating volatility in prices to customers and stabilizing returns to investors. Such rate structures were in place in all of Southwest’s operating areas during all periods for which results of natural gas operations are disclosed above.

Arizona Jurisdiction

Arizona General Rate Case. In May 2019, Southwest filed a general rate case application requesting to increase revenue by approximately $57 million to update the cost of service to reflect recent U.S. tax reform changes, incorporating the return of excess deferred income taxes to customers, and to reflect capital investments, including certain post-test year additions and the southern Arizona liquefied natural gas (“LNG”) facility. The application included a proposed 10.3% return on equity (“ROE”) relative to a capital structure of 51.1% equity. Southwest updated its request to reflect the actual amortization of excess accumulated deferred income taxes (“EADIT”) resulting from U.S. tax reform, and to include additional post-test year plant associated with its customer-owned yard line (“COYL”) and vintage steel pipe (“VSP”) programs, discussed further below. The amendment increased the deficiency by $36 million, to $93 million, which was further updated to $90.6 million based on certain aspects of cost of service, including a revised proposed ROE of 10.15%. The request and amendments included the retention of a fully decoupled rate design, other previously approved regulatory mechanisms, and a new infrastructure tracking mechanism for specific plastic pipe, in addition to a proposal for a renewable natural gas (“RNG”) program as part of its PGA mechanism. Southwest entered into a stipulation for certain aspects of the case, agreeing to continue the COYL program; to establish a Tax Expense Adjustor Mechanism to track annual changes in the amortization of EADIT, as well as any future changes in the federal tax rate; to include a 10-year amortization of EADIT associated with deemed “unprotected” plant; and to incorporate various tariff proposals. EADIT associated with “protected” plant relates to timing differences from using accelerated depreciation for tax purposes and another method for book purposes, and unprotected amounts relate to all other timing differences. Following the hearing and legal briefing process, this requested amount was further updated to $80.7 million to reflect agreements by the parties on the treatment of EADIT and certain other ratemaking adjustments.

A final decision was issued in December 2020, with new rates becoming effective in January 2021, resulting in an overall annual revenue increase of $36.8 million, and the continuation of both full revenue decoupling and the COYL program. An ROE of 9.1% was approved with a capital structure comprised of 48.9% long-term debt and 51.1% common equity. The overall increase reflects the final ROE and the inclusion of a six-month period covering certain post-test year plant additions, as well as the post-test year plant addition of the LNG facility. See additional discussion related to these programs below. The continuation of the property tax tracker was supported in the final decision, as was the Tax Expense Adjustor Mechanism (noted above). While the RNG proposal was not approved as part of the decision, the ACC agreed to conduct a workshop to further explore the role of RNG in Arizona.

Delivery Charge Adjustment. The Delivery Charge Adjustment (“DCA”) is filed each April, which along with other reporting requirements, contemplates a rate to recover the over- or under-collected margin tracker amounts based on the balance at the end of the preceding calendar year. In April 2020, Southwest filed to adjust the existing rate to consider the 14-month period of January 1, 2019 through February 29, 2020, proposing a rate of $0.00655 per therm based on an ending balance of approximately $3.5 million. Although Commission Staff concurred with Southwest’s proposed rate, the ACC ultimately elected to reduce the rate to zero in an effort to provide some measure of customer relief in light of current issues related to the COVID-19 pandemic, and at the time of both the April filing and the ACC decision, the balance was a liability (in an over-recovered status). Activity through the remainder of 2020 resulted in a modest under-collected balance at December 31, 2020, and an over-collected balance of $9.5 million exists as of March 31, 2021.

LNG Facility. In 2014, Southwest sought ACC preapproval to construct, operate, and maintain a 233,000 dekatherm LNG facility in southern Arizona. This facility is intended to enhance service reliability and flexibility related to natural gas deliveries in the southern Arizona area by providing a local storage option, and to be connected directly to Southwest’s

34

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

distribution system. Southwest was ultimately granted approval for construction and deferral of costs. The facility was placed in service in December 2019. The capital costs and the operating expenses associated with plant operation were considered and approved as part of Southwest’s recently approved general rate case. Due to the timing of the approximate $12 million in operating costs incurred following the in-service date, a proposal to recover the associated regulatory asset balance will be included in the next Arizona general rate case application.

COYL Program. Southwest received approval, in connection with its 2010 Arizona general rate case, to implement a program to conduct leak surveys, and if leaks were present, to replace and relocate service lines and meters for Arizona customers whose meters were set off from the customer’s home, representing a non-traditional configuration. In 2014, the ACC approved a “Phase II” of the COYL program, which included the replacement of non-leaking COYLs. Annual surcharges were designed to collect the revenue requirement associated with the program. In a February 2019 filing, Southwest requested to increase its surcharge to recover a revenue requirement of $6.7 million (an increase of $3.2 million) associated with $26.6 million in capital projects completed in 2018. The ACC ultimately issued an Order in October 2019 authorizing Southwest to retain the existing annual surcharge in place, while it reviewed the program as part of the general rate case. Southwest also included an estimated $21.1 million related to the 2019 COYL capital projects as part of the rate case. Parties to the rate case stipulated to continue the COYL program and recommended recovery of the plant as part of Southwest’s filed post-test year plant adjustment, with inclusion of related amounts in base rates. Further consideration in the rate case decision limited post-test year plant to six months (inclusive of COYL plant), and limited future COYL activity to the replacement of leaking COYLs, or in cases when other replacement activity is taking place in the vicinity. A filing in the second quarter of 2021 will propose the recovery of the revenue requirement associated with the 2019 and 2020 COYL activity and plant placed in service following the six-month post-test year inclusion period of the recently concluded rate case.

VSP Program. Southwest received approval, in connection with its 2016 Arizona general rate case, to implement a VSP replacement program, due to having a substantial amount of pre-1970s vintage steel pipe in Arizona. As part of the program, Southwest proposed to begin replacing the pipe on an accelerated basis and recover the costs through an annual surcharge filing. Once implemented, surcharges to collect the annual revenue requirement associated with the capital expenditures were designed to be revised annually under the program. In February 2019, Southwest requested to increase its surcharge revenue by $9.5 million (to $11.9 million) associated with the replacement of approximately $100 million in 2018 VSP capital projects. The ACC issued an Order in October 2019 authorizing Southwest to retain the existing annual surcharge, and indicated it would review the program as part of the general rate case. Southwest also proposed to have the ACC review an estimated $103.4 million of 2019 VSP capital projects as part of the rate case. As noted above, the decision in the general rate case provided for a post-test year plant adjustment period of six months (inclusive of VSP). However, the ACC ultimately decided to discontinue the accelerated VSP program at this time. A filing in the second quarter of 2021 will propose the recovery of the revenue requirement associated with the 2019 and 2020 VSP activity and plant placed in service following the six month post-test year inclusion period of the recently concluded rate case.

Customer Data Modernization Initiative. Southwest embarked on an initiative to replace its customer service system and gas transaction systems, each to be utilized to support all Southwest service territories. Combined, these undertakings are referred to as the Customer Data Modernization Initiative (the “CDMI”). In March 2019, Southwest filed an application with the ACC seeking an accounting order to track and defer all costs associated with the CDMI to mitigate adverse financial implications associated with this multi-year initiative. The commission issued a decision in this matter in early April 2021 denying Southwest’s request for a regulatory asset, indicating that the requested recovery mechanism was not warranted. Therefore, the costs will be considered as part of a future general rate proceeding. The total cost for the CDMI was estimated at approximately $174 million, $96 million of which would be allocable to the Arizona rate jurisdiction. The customer service system was placed in service in May 2021 and the gas transaction system will follow later in 2021.

California Jurisdiction

California General Rate Case. In August 2019, Southwest filed a general rate case based on a 2021 test year, seeking authority to increase rates in its California rate jurisdictions, after being granted earlier permission to extend the rate case cycle by two years and continue its 2.75% previously approved Post-Test Year (“PTY”) attrition adjustments for 2019 and 2020. The proposed combined revenue increase of $12.8 million was net of a $10.9 million revenue reduction associated with changes from U.S. tax reform, which included the amortization of $9.8 million (approximately $2 million annually over five years) associated with the difference in authorized income tax expense and actual incurred income tax expense for years 2019 and 2020, which when returned would impact cash flows, but not expected to have an impact on earnings. Southwest tracked those amounts, as directed, and reserved them for return to customers. The overall revenue request also included $1.6 million of EADIT proposed to be returned to customers each year until the amount is reset as part of a future rate case. Southwest’s proposal included an ROE of 10.5%, relative to a 53% equity ratio; continuation of annual post-test year margin adjustments of 2.75%; implementation of various safety-related programs, including a targeted pipe replacement program and a meter

35

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

protection program (with a combination of measures, such as snow sheds, excess flow valves, upgraded meter set piping and upgraded Encoder Receiver Transmitter protocol); as well as an expansion of the school COYL replacement program.

Southwest reached an agreement in principle with the Public Advocate’s Office for settlement of the general rate case, which was unanimously approved by the Commission on March 25, 2021, including a $6.4 million total combined revenue increase with a 10% ROE, relative to a 52% equity ratio. Approximately $4 million of the original proposed increase of $12.8 million was associated with a North Lake Tahoe project that would not ultimately be completed by the beginning of 2021; consequently, the parties agreed to remove it from the base rate increase and instead provide for recovery of the cost of the project through a future surcharge. The decision also maintains Southwest’s existing 2.75% annual attrition adjustments, the continuation of the pension balancing account, and a proposed increase in the residential basic service charge from the existing $5.00 to $5.75 per month. It also includes a cumulative total of $119 million over the five-year rate cycle to implement risk-informed proposals, consisting of the school COYL replacement, meter protection, and pipe replacement programs. Although new rates were originally anticipated to be in place by January 1, 2021, in light of an administrative delay, Southwest was granted authority to establish a general rate case memorandum account to track the margin/revenue impacts related to the delay in the implementation of new rates. Such rates were ultimately implemented April 1, 2021.

Attrition Filing. Since Southwest’s general rate case test year is 2021, there is no separate attrition increase for 2021; however, the PTY attrition increases of 2.75% will continue in 2022, as approved in the most recent rate case decision.

Greenhouse Gas (“GHG”) Compliance. California Assembly Bill Number 32 and regulations promulgated by the California Air Resources Board, require Southwest, as a covered entity, to comply with applicable requirements associated with California GHG emissions reporting and the California Cap and Trade Program. The CPUC issued a decision in 2018 adopting an allocation methodology to distribute the net revenues or costs. Southwest began amortizing its then existing net cost balance over a 12-month period with recovery rates effective July 2018 for all applicable rate schedules. In addition, for years 2019-2020, the decision adopted an allocation methodology to distribute the revenue proceeds through a California Climate Credit to active residential customers in April of each year, following initial required credits in October 2018. Amounts distributed in April 2019 and 2020 were comparable. GHG compliance costs recovered through rates have no impact on earnings.

Renewable Natural Gas. In February 2019, Southwest filed an application that, among other things, sought to formally allow renewable natural gas (or biomethane) as an includible component of Southwest’s gas supply portfolio through the Biomethane Gas Program (“BGP”). This proposal was designed to further the goals of the California Global Warming Solutions Act of 2006, the California Low Carbon Fuel Standard, Senate Bills 1383 and 1440, as well as current or future legislative or regulatory efforts to reduce greenhouse gas emissions. Implementation of the BGP addresses cost recovery as part of Southwest’s existing Gas Cost Incentive Mechanism related to the purchase or sale of biomethane. The CPUC issued a final decision approving the proposal in March 2020.

Customer Data Modernization Initiative. In April 2019, Southwest filed an application with the CPUC seeking authority to establish a two-way, interest bearing balancing account to record costs associated with the CDMI to mitigate adverse financial implications associated with this multi-year project. Approximately $19 million of the estimated $174 million total for the CDMI would be allocable to the California rate jurisdiction. Southwest filed a separate request to establish a memorandum account while the CPUC considered its application request to establish the two-way balancing account. Effective October 2019, the CPUC granted Southwest’s memorandum account request, which would allow Southwest to track costs, including operations and maintenance costs and capital-related costs, such as depreciation, taxes, and return associated with California’s portion of the CDMI. The balance tracked in the memorandum account would be transferred to the two-way balancing account, if approved. In January 2020, Southwest and the Public Advocates Office reached a settlement agreement to adopt Southwest’s Application and the CPUC issued a final decision approving the settlement agreement as filed in July 2020. A rate to begin recovering the balance accumulated through June 30, 2020 was established and made effective September 1, 2020, further updated in January 2021, and will be updated annually thereafter each January.

Emergency Relief Program Related to COVID-19. In March 2020, in light of the COVID-19 pandemic, Southwest requested to establish a memorandum account to track costs as part of customer protections under Emergency Relief regulations implemented in California in 2019 (in the event of a state or federal declared emergency or disaster). The CPUC passed an emergency resolution on April 16, 2020 authorizing and directing utilities to implement customer protections and to establish memorandum accounts to track the financial impacts of complying with the resolution. On May 1, 2020, Southwest requested to establish a COVID-19 Pandemic Protections Memorandum Account (“CPPMA”) to record all incremental costs and lost revenues incurred by Southwest associated with its implementation of the COVID-19 customer protections as outlined in the CPUC resolution. The customer protections were retroactively applied to March 4, 2020, the date Governor Gavin Newsom declared a state of emergency related to COVID-19. The CPPMA was originally effective March 4, 2020 through April 16, 2021, but was extended through June 30, 2021. These customer protections focus on flexible payment plan options, additional

36

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

protections for income-qualified customers, as well as the suspension of disconnections for non-payment and the waiver of deposit and late fee requirements. Tracked amounts will be considered by the CPUC for future recovery.

Nevada Jurisdiction

Nevada General Rate Case. Southwest filed a general rate case application with the PUCN in February 2020, which requested a statewide overall general rate increase of approximately $38.3 million. The request sought an ROE of 10% relative to a proposed capital structure of 50% equity and continuation of the General Revenues Adjustment (“GRA”) mechanism (full revenue decoupling). The request also proposed the recovery of previously excluded costs attributable to several software applications. In June 2020, Southwest submitted its certification filing to update certain balances through May 31, 2020, which increased its overall proposed rate increase to $38.5 million. The commission issued its final order in September 2020, which provided for an authorized combined revenue increase of approximately $23 million for northern and southern Nevada and continuation of the currently authorized 9.25% ROE, with a capital structure of 49.26% equity and 50.74% debt. Southwest’s existing GRA was authorized to continue without modification. Full cost recovery of the unamortized balance of excluded software projects from the previous general rate case was authorized in this case, along with the inclusion of all proposed Gas Infrastructure Replacement (“GIR”) and Mesquite Expansion projects in rate base, and full recovery of test year and certification operations and maintenance expenses associated with the CDMI project. Rates became effective in October 2020.

In association with the previous Nevada rate case decision in December 2018, management requested reconsideration of several issues in the case; however, the PUCN ultimately granted no further rate relief. Management decided to seek judicial review of the PUCN’s rate order, which was considered in January 2020. The District Court Judge deferred to the PUCN’s original findings. In March 2020, Southwest filed an appeal with the Nevada Supreme Court, which remains active; the resolution will likely take 12-24 months from the date of the appeal. 

General Revenues Adjustment. The continuation of the GRA was affirmed as part of Southwest’s recently concluded general rate case, effective October 2020. Southwest makes Annual Rate Adjustment (“ARA”) filings to update rates to recover or return amounts associated with various regulatory mechanisms, including the GRA. In June 2019, Southwest made its annual filing, which provided for a decrease of approximately $8 million for an over-collected balance in southern Nevada and an increase of approximately $2 million in northern Nevada. The proposed changes were approved, with rates effective January 2020. In May 2020, Southwest made its most recent ARA filing, which proposed an annualized margin decrease of $5.3 million in southern Nevada and an increase of $1.6 million in northern Nevada. The ARA filing was resolved through a settlement of the parties, in which the proposed changes associated with the GRA were approved, effective January 2021. While there is no impact to net income overall from adjustments to recovery rates associated with the related regulatory balances, operating cash flows are impacted by such changes.

Infrastructure Replacement Mechanism. In 2014, the PUCN approved final rules for the GIR mechanism, which defers and provides for recovery of certain costs associated with accelerated replacement of qualifying infrastructure that would not otherwise currently provide incremental revenues. Associated with the replacement of various types of pipe infrastructure under the mechanism (Early Vintage Plastic Pipe, COYL, and VSP), the related regulations provide Southwest with the opportunity to file a GIR “Advance Application” annually, generally in May, to seek preapproval of qualifying replacement projects.

Furthermore, a GIR rate application is generally filed each October to reset the GIR recovery surcharge rate related to previously approved and completed projects, with new rates typically becoming effective each January. On October 1, 2019, Southwest filed a rate application to reset the recovery surcharge to include cumulative deferrals through August 31, 2019. This surcharge rate became effective February 2020, designed to result in a reduction in annual revenue of approximately $5.3 million in southern Nevada and no incremental revenue in northern Nevada. On September 30, 2020, Southwest filed its latest rate application to reset the recovery surcharge to include cumulative deferrals through August 31, 2020. The updated surcharge rate is expected to result in a reduction in annual revenue of approximately $11.8 million, and became effective January 2021.

Conservation and Energy Efficiency. The PUCN allows deferral (and later recovery) of approved conservation and energy efficiency costs, recovery rates for which are adjusted in association with ARA filings. In its June 2019 ARA filing, Southwest proposed annualized margin increases of $3.2 million and $880,000 in southern and northern Nevada, respectively. However, Southwest entered into a stipulation and agreement to modify these amounts to $6.2 million and $1.1 million in southern and northern Nevada, respectively, which reflected the recovery of a related but separate program balance to be rolled into customer rates with the same effective date. The modification was approved, and rates became effective January 2020. In its May 2020 ARA filing, Southwest proposed annualized margin decreases of $313,000 and $55,000 for southern and northern Nevada, respectively, which were approved and became effective January 2021.

Expansion and Economic Development Legislation. In January 2016, final regulations were approved by the PUCN associated with legislation (“SB 151”) previously introduced and signed into law in Nevada. The legislation authorized natural gas utilities

37

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

to expand their infrastructure to provide service to unserved and underserved areas in Nevada.

In November 2017, Southwest filed for preapproval of a project to extend service to Mesquite, Nevada, in accordance with the SB 151 regulations. Ultimately, the PUCN issued an order approving Southwest’s proposal for the expansion. The order approved a capital investment of approximately $28 million and the construction of approximately 37 miles of distribution pipeline (including the approach main). The annual revenue requirement associated with the project is $2.8 million. A volumetric rate, applicable to all southern Nevada customers (including new customers in Mesquite), was implemented in October 2019 to recover the cost. Southwest’s May 2020 ARA filing, which proposed an annualized margin increase of $185,000, reflects the cumulative deferred revenue requirement associated with the Mesquite facilities that were placed in service through April 30, 2020. During 2020, Southwest continued serving certain customers in Mesquite from an approved “virtual” pipeline network, providing temporary natural gas supply using portions of the approved distribution system and compressed natural gas. Construction of the tap site, approach main, as well as distribution mains was completed and facilities were placed in service in December 2020.

In June 2019, Southwest filed for preapproval to construct the infrastructure necessary to expand natural gas service to Spring Creek, Nevada, and to implement a cost recovery methodology to timely recover the associated revenue requirement consistent with the SB 151 regulations. Expansion to the Spring Creek area near Elko, Nevada consists of a high-pressure approach main and associated regulator stations, an interior backbone, and the extension of the distribution system from the interior backbone system. The total capital investment was estimated to be $61.9 million. A stipulation in this matter was reached with the parties and approved by the PUCN in December 2019, which largely accepted Southwest’s proposal with modifications reflected in the rate recovery allocations split amongst northern Nevada, Elko, and Spring Creek expansion customers. Construction of the initial phase of the expansion began in the third quarter of 2020, and service commenced to the first Spring Creek customers in December 2020.

Customer Data Modernization Initiative. In March 2019, Southwest filed a request seeking authority to establish a regulatory asset to defer the revenue requirement related to the CDMI to mitigate the financial attrition associated with the multi-year project. Approximately $59 million of the estimated $174 million cost of the CDMI would be allocable to the Nevada rate jurisdictions. A hearing on this matter was held in August 2019 and the PUCN issued its decision in September 2019, denying Southwest’s request for regulatory asset treatment, finding a general rate case to be the most appropriate avenue to address such costs. In response to the PUCN’s decision, Southwest filed a Petition for Reconsideration in October 2019, which was denied. As part of Southwest’s recently approved general rate case filing, Southwest was authorized to include CDMI operations and maintenance costs since the beginning of the test year as part of its revenue requirement in the case. The customer service system portion of the project was placed in service in May 2021, and the gas transaction system portion is expected to follow later in 2021.

Regulatory Asset Related to COVID-19. The PUCN issued an order directing utilities within the state to establish regulatory asset accounts, effective March 12, 2020, the date that Governor Steve Sisolak declared a state of emergency related to COVID-19, to track the financial impacts associated with maintaining service for customers affected by COVID-19, including those whose service would have been otherwise terminated/disconnected. These costs will be considered by the PUCN for future recovery.

FERC Jurisdiction

General Rate Case. Paiute Pipeline Company (“Paiute”), a wholly owned subsidiary of Southwest, filed a general rate case with the FERC in May 2019. The filing fulfilled an obligation from the settlement agreement reached in the 2014 Paiute general rate case. In January 2020, Paiute reached an agreement in principle with the FERC Staff and intervenors to settle its most recent general rate case. In addition to continuing the term-differentiated rate structures with its shippers, the agreement requires Paiute’s three largest transportation customers and all of its storage customers to extend their service agreements to have primary terms of at least five years. The settlement resulted in a revenue reduction of approximately $700,000 and is based on a 9.90% pre-tax rate of return. Also as part of this agreement, Paiute agreed not to file a rate case prior to January 1, 2022, but no later than May 31, 2025.

In January 2020, Paiute requested, and was granted, the authority to place the settlement rates into effect on an interim basis, effective February 2020. On March 30, 2020, Paiute filed the proposed settlement agreement with the FERC for review and approval. On July 6, 2020, the FERC issued a letter order approving the settlement, and the order became final on August 5, 2020.

38

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

PGA Filings

The rate schedules in all of Southwest’s service territories contain provisions that permit adjustment to rates as the cost of purchased gas changes. These deferred energy provisions and purchased gas adjustment clauses are collectively referred to as “PGA” clauses. Differences between gas costs recovered from customers and amounts paid for gas by Southwest result in over- or under-collections. Balances are recovered from or refunded to customers on an ongoing basis with interest. As of March 31, 2021, under-collections in each of Southwest’s service territories resulted in an asset of $238.9 million on the Company’s and Southwest’s Condensed Consolidated Balance Sheets. The significant change in the PGA balance was due to incremental natural gas costs associated with an extreme weather event in the central U.S. in mid-February 2021. See also Deferred Purchased Gas Costs in Note 1 – Background, Organization, and Summary of Significant Accounting Policies in this quarterly report on Form 10-Q.

Filings to change rates in accordance with PGA clauses are subject to audit by state regulatory commission staffs. PGA changes impact cash flows but have no direct impact on profit margin. However, gas cost deferrals and recoveries can impact comparisons between periods of individual consolidated income statement components. These include Gas operating revenues, Net cost of gas sold, Net interest deductions, and Other income (deductions).

The following table presents Southwest’s outstanding PGA balances receivable/(payable):

(Thousands of dollars)	March 31, 2021		December 31, 2020		March 31, 2020
Arizona	$	194,446	$	(3,901)	$	(17,538)
Northern Nevada	3,036		(8,601)		(3,154)
Southern Nevada	31,849		(42,134)		(2,585)
California	9,555		2,053		(3,221)
	$	238,886	$	(52,583)	$	(26,498)

Capital Resources and Liquidity

Historically, cash on hand and cash flows from operations have provided a substantial portion of cash used in investing activities (primarily for construction expenditures and property additions). In recent years, Southwest has undertaken significant pipe replacement activities to fortify system integrity and reliability, including on an accelerated basis in association with certain gas infrastructure replacement programs. This accelerated activity has necessitated the issuance of both debt and equity securities to supplement cash flows from operations. The Company endeavors to maintain an appropriate balance of equity and debt to preserve investment-grade credit ratings, which should minimize interest costs.

Cash Flows

Southwest Gas Holdings, Inc.:

Operating Cash Flows. Cash flows from consolidated operating activities decreased $324 million in the first three months of 2021 as compared to the same period of 2020. The decline in cash flows primarily resulted from amounts under purchased gas adjustment mechanisms, including amounts resulting from the temporary escalation in gas commodity prices during the first quarter of 2021 associated with the extreme cold temperatures in the central U.S. (see Note 1 – Background, Organization, and Summary of Significant Accounting Policies), and also from a decrease ($25 million) in recoveries related to the Arizona decoupling mechanism balance between three-month periods.

Investing Cash Flows. Cash used in consolidated investing activities decreased $56 million in the first three months of 2021 as compared to the same period of 2020. The change was primarily due to a decrease in capital expenditures in both reportable segments.

Financing Cash Flows. Net cash provided by consolidated financing activities increased $265 million in the first three months of 2021 as compared to the same period of 2020. The change was primarily due to Southwest’s $250 million Term Loan issued in the first quarter of 2021 to fund the increased cost of natural gas supply noted above during the extreme cold weather event. Additionally, the Company issued $46 million in common stock under its equity shelf program in the first three months of 2021. Other changes relate to borrowing and repayment activity related to the credit facilities between comparative periods in both segments, and proceeds from a $50 million equipment loan in the prior-year quarter.

During the three months ended March 31, 2021, the Company also issued 49,500 shares of common stock through the Dividend Reinvestment and Stock Purchase Plan, raising approximately $3.1 million.

The capital requirements and resources of the Company generally are determined independently for the natural gas operations and utility infrastructure services segments. Each business activity is generally responsible for securing its own external debt

39

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

financing sources. However, the holding company may raise funds through stock issuances or other external financing sources. See Note 4 – Common Stock.

Southwest Gas Corporation:

Operating Cash Flows. Cash flows from operating activities decreased $354 million in the first three months of 2021 as compared to the same period of 2020. The decline in operating cash flows was primarily attributable to the impacts related to deferred purchased gas costs and the Arizona decoupling mechanism noted above.

Investing Cash Flows. Cash used in investing activities decreased $44 million in the first three months of 2021 as compared to the same period of 2020. The change was due to a decrease in capital expenditures in 2021. See also Gas Segment Construction Expenditures and Financing below.

Financing Cash Flows. Net cash provided by financing activities increased $304 million in the first three months of 2021 as compared to the same period of 2020. The increase was primarily due to Southwest’s $250 million Term Loan issued in the first quarter of 2021 to fund the increased cost of natural gas supply noted above related to the extreme cold weather event. Additionally, in the prior-year period, Southwest had more repayment activity for the portion of its revolving credit facility that is designated for working capital purposes. See Note 5 – Debt.

Gas Segment Construction Expenditures and Financing

During the twelve-month period ended March 31, 2021, construction expenditures for the natural gas operations segment were $647 million. The majority of these expenditures represented costs associated with scheduled and accelerated replacement of existing transmission, distribution, and general plant.

Management estimates natural gas segment construction expenditures during the three-year period ending December 31, 2023 will be approximately $2.1 billion. Of this amount, approximately $700 million is scheduled to be incurred in 2021. Southwest plans to continue to request regulatory support to undertake projects, or to accelerate projects as necessary, for the improvement of system flexibility and reliability, or to expand, where relevant, to unserved or underserved areas. Southwest may expand existing, or initiate new, programs. Significant replacement activities are expected to continue well beyond the next few years. See also Rates and Regulatory Proceedings. During the three-year period, cash flows from operating activities of Southwest are expected to provide approximately 50% of the funding for gas operations and total construction expenditures and dividend requirements. Any additional cash requirements, including construction-related and paydown or refinancing of debt, are expected to be provided by existing credit facilities, equity contributions from the Company, and/or other external financing sources. The timing, types, and amounts of additional external financings will be dependent on a number of factors, including the cost of gas purchases, conditions in the capital markets, timing and amounts of rate relief, timing and amounts of surcharge collections from, or amounts returned to, customers related to other regulatory mechanisms and programs, as well as growth levels in Southwest’s service areas and earnings. External financings may include the issuance of debt securities, bank and other short-term borrowings, and other forms of financing.

In May 2019, the Company filed with the Securities and Exchange Commission (the “SEC”) an automatic shelf registration statement for the offer and sale of up to $300 million of common stock from time to time in at-the-market offerings under the prospectus included therein in accordance with the Sales Agency Agreement, dated May 8, 2019, between the Company and BNY Mellon Capital Markets, LLC. The Company issued the remaining capacity ($46 million) under this equity program during the quarter ended March 31, 2021. During the twelve months ended March 31, 2021, 2,623,469 shares were issued in at-the-market offerings at an average price of $66.96 per share with gross proceeds of $175.7 million, agent commissions of $1.8 million, and net proceeds of $173.9 million under this equity shelf program.

In April 2021, the Company entered into a Sales Agency Agreement between the Company and BNY Mellon Capital Markets, LLC and J.P. Morgan Securities LLC for the offer and sale of up to $500 million of common stock from time to time in at-the-market offerings under the related prospectus supplement filed with the SEC the same month. Net proceeds from the sales of common stock under this 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, as well as for the repayment or repurchase of indebtedness (including amounts outstanding from time to time under the credit facilities, senior notes, Term Loan or future credit facilities), and to provide for working capital.

Bonus Depreciation

In 2017, with the enactment of U.S. tax reform, the bonus depreciation deduction percentage changed from 50% to 100% for “qualified property” placed in service after September 27, 2017 and before 2023. The bonus depreciation tax deduction phases out starting in 2023, by 20% for each of the five following years. Qualified property excludes most public utility property. The

40

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Company estimates bonus depreciation will defer the payment of approximately $20 million of federal income taxes for 2021, none of which relates to natural gas operations.

Dividend Policy

Dividends are payable on the Company’s common stock at the discretion of the Board of Directors (the “Board”). In setting the dividend rate, the Board currently targets a payout ratio of 55% to 65% of consolidated earnings per share and considers, among other factors, current and expected future earnings levels, our ongoing capital expenditure plans and expected external funding needs, in addition to our ability to maintain strong credit ratings and liquidity. The Company has paid dividends on its common stock since 1956 and has increased that dividend each year since 2007. In February 2021, the Board elected to increase the quarterly dividend from $0.57 to $0.595 per share, representing a 4.4% increase, effective with the June 2021 payment.

Liquidity

Liquidity refers to the ability of an enterprise to generate sufficient amounts of cash through its operating activities and external financing to meet its cash requirements. Several factors (some of which are out of the control of the Company) that could significantly affect liquidity in the future include: variability of natural gas prices, changes in ratemaking policies of regulatory commissions, regulatory lag, customer growth in the natural gas segment, the ability to access and obtain capital from external sources, interest rates, changes in income tax laws, pension funding requirements, inflation, and the level of earnings. Natural gas prices and related gas cost recovery rates, as well as plant investment, have historically had the most significant impact on liquidity.

On an interim basis, Southwest defers over- or under-collections of gas costs to PGA balancing accounts. In addition, Southwest uses this mechanism to either refund amounts over-collected or recoup amounts under-collected as compared to the price paid for natural gas during the period since the last PGA rate change went into effect. At March 31, 2021, the combined balance in the PGA accounts totaled an under-collection of $239 million. See PGA Filings for more information.

In March 2021, Southwest issued a $250 million Term Loan that will mature in March 2022, or 364 days after issuance. The proceeds were 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.

Southwest Gas Holdings, Inc. has a credit facility with a borrowing capacity of $100 million that expires in April 2025. This facility is intended for short-term financing needs. At March 31, 2021, $43 million was outstanding under this facility.

Southwest has a credit facility, with a borrowing capacity of $400 million, which expires in April 2025. Southwest designates $150 million of the facility for long-term borrowing needs and the remaining $250 million for working capital purposes. The maximum amount outstanding on the long-term portion of the credit facility (including a commercial paper program, as noted below) during the first three months of 2021 was $150 million, the same amount which was outstanding as of March 31, 2021. The maximum amount outstanding on the short-term portion of the credit facility during the first quarter of 2021 was $125 million. As of March 31, 2021, $17 million was outstanding on the short-term portion of this credit facility. The credit facility can be used as necessary to meet liquidity requirements, including temporarily financing under-collected PGA balances, or meeting the refund needs of over-collected balances. The credit facility has been adequate for Southwest’s working capital needs outside of funds raised through operations and other types of external financing. As indicated, any additional cash requirements would include the existing credit facility, equity contributions from the Company, and/or other external financing sources.

Southwest has a $50 million commercial paper program. Any issuance under the commercial paper program is supported by Southwest’s current revolving credit facility and, therefore, does not represent additional borrowing capacity. Any borrowing under the commercial paper program during 2021 will be designated as long-term debt. Interest rates for the commercial paper program are calculated at the current commercial paper rate during the borrowing term. At March 31, 2021, there was $50 million outstanding under this program.

Centuri has a senior secured revolving credit and term loan facility with borrowing capacity of $590 million (refer to Note 5 – Debt). The line of credit portion comprises $325 million; associated amounts borrowed and repaid are available to be re-borrowed. The term loan facility portion has a limit of approximately $265 million. The $590 million credit and term loan facility expires in November 2023. It is secured by substantially all of Centuri’s assets except those explicitly excluded under the terms of the agreement (including owned real estate and certain certificated vehicles). Centuri assets securing the facility at March 31, 2021 totaled $1.3 billion. The maximum amount outstanding on the combined facility during the first three months of 2021 was $249 million, at which point $223 million was outstanding on the term portion. As of March 31, 2021, $26 million was outstanding on the revolving credit facility, in addition to the $223 million that remained outstanding on the term loan portion of the facility. Also at March 31, 2021, there was approximately $267 million, net of letters of credit, available for borrowing under the line of credit.

41

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

Interest rates for the credit facilities of the holding company, Southwest, and Centuri, and for Southwest’s Term Loan contain LIBOR-based rates. Upon the occurrence of certain events providing for a transition away from LIBOR, or if LIBOR is no longer a widely recognized benchmark rate, the holding company and Southwest may amend their respective credit facility as set forth in the credit facility agreement, and also in the case of Southwest’s Term Loan, to accommodate a replacement benchmark as set forth in the agreements. LIBOR is scheduled to be discontinued as a benchmark or reference rate after 2021. In order to mitigate the impact of a discontinuance on the Company’s and Southwest’s financial condition and results of operations, management will monitor developments and work with lenders, where relevant, to determine the appropriate replacement/alternative reference rate for variable rate debt. At this time the Company and Southwest can provide no assurances as to the impact a LIBOR discontinuance will have on their financial condition or results of operations. Any alternative rate may be less predictable or less attractive than LIBOR.

The Company has a Sales Agency Agreement with BNY Mellon Capital Markets, LLC and J.P. Morgan Securities LLC for the offer and sale of up to $500 million of common stock from time to time in at-the-market offerings, which is an additional source of liquidity.

Forward-Looking Statements

This quarterly report contains statements which constitute “forward-looking statements” within the meaning of the Private Securities Litigation Reform Act of 1995 (“Reform Act”). All statements other than statements of historical fact included or incorporated by reference in this quarterly report are forward-looking statements, including, without limitation, statements regarding the Company’s plans, objectives, goals, intentions, projections, strategies, future events or performance, negotiations, and underlying assumptions. The words “may,” “if,” “will,” “should,” “could,” “expect,” “plan,” “anticipate,” “believe,” “estimate,” “predict,” “project,” “continue,” “forecast,” “intend,” “endeavor,” “promote,” “seek,” and similar words and expressions are generally used and intended to identify forward-looking statements. For example, statements regarding operating margin patterns, customer growth, the composition of our customer base, price volatility, seasonal patterns, payment of debt, the Company’s COLI strategy, replacement market and new construction market, impacts from the COVID-19 pandemic, including on our employees, customers, or otherwise, our financial position, revenue, earnings, cash flows, debt covenants, operations, regulatory recovery, work deployment or resumption and related uncertainties stemming from this pandemic, expected impacts of valuation adjustments associated with any redeemable noncontrolling interest, the impacts of U.S. tax reform including disposition in any regulatory proceeding and bonus depreciation tax deductions, the impact of recent PHMSA rulemaking, the amounts and timing for completion of estimated future construction expenditures, plans to pursue infrastructure programs or programs under SB151 legislation, forecasted operating cash flows and results of operations, net earnings impacts or recovery of costs from gas infrastructure replacement and COYL programs and surcharges, funding sources of cash requirements, amounts generally expected to be reflected in future period revenues from regulatory rate proceedings including amounts requested or settled from recent and ongoing general rate cases or other regulatory proceedings, the outcome of judicial review of the previous Nevada rate case, rates and surcharges, PGA administration and recovery, and other rate adjustments, sufficiency of working capital and current credit facilities, bank lending practices, the Company’s views regarding its liquidity position, ability to raise funds and receive external financing capacity and the intent and ability to issue various financing instruments and stock under the existing at-the-market equity program or otherwise, future dividend increases and the Board’s current target dividend payout ratio, pension and postretirement benefits, certain impacts of tax acts, the effect of any other rate changes or regulatory proceedings, contract or construction change order negotiations, impacts of accounting standard updates, statements regarding future gas prices, gas purchase contracts and pipeline imbalance charges or claims related thereto, recoverability of regulatory assets, the impact of certain legal proceedings, and the timing and results of future rate hearings, including any ongoing or future general rate cases and other proceedings, the final resolution for recovery of the CDMI in all jurisdictions, and statements regarding pending approvals are forward-looking statements. All forward-looking statements are intended to be subject to the safe harbor protection provided by the Reform Act.

A number of important factors affecting the business and financial results of the Company could cause actual results to differ materially from those stated in the forward-looking statements. These factors include, but are not limited to, customer growth rates, conditions in the housing market, the impacts of COVID-19 including that which may result from a continued or sustained restriction on commerce by government officials or otherwise, including impacts on employment in our territories, the health impacts to our customers and employees due to the persistence of the virus or efficacy of vaccines, the ability to collect on customer accounts due to the current or an extended moratorium on late fees or service disconnection, the ability to obtain regulatory recovery of all costs and financial impacts resulting from this pandemic, the ability of the infrastructure services business to resume work with all customers and the impact of a delay or termination of work as a result thereof, the impacts of future restrictions placed on our business by government regulation or otherwise (such as self-imposed restrictions for the safety of employees and customers), including related to personal distancing, investment in personal protective equipment and other protocols, the impact of a resurgence of the virus following the ongoing resumption of commerce in our territories, and decisions of Centuri customers as to whether to pursue capital projects due to economic impacts resulting from the pandemic or

42

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

otherwise, the ability to recover and timing thereof related to costs associated with the PGA mechanisms or other regulatory assets, the effects of regulation/deregulation, governmental or regulatory policy regarding pipeline safety, greenhouse gas emissions, natural gas or alternative energy, the regulatory support for ongoing infrastructure programs or expansions, the timing and amount of rate relief, the timing and methods determined by regulators to refund amounts to customers resulting from U.S. tax reform, changes in rate design, variability in volume of gas or transportation service sold to customers, changes in gas procurement practices, changes in capital requirements and funding, the impact of credit rating actions and conditions in the capital markets on financing costs, the impact of variable rate indebtedness associated with a discontinuance of LIBOR including in relation to amounts of indebtedness then outstanding, changes in construction expenditures and financing, changes in operations and maintenance expenses, effects of pension expense forecasts, accounting changes and regulatory treatment related thereto, currently unresolved and future liability claims and disputes, changes in pipeline capacity for the transportation of gas and related costs, results of Centuri bid work, the impact of weather on Centuri’s operations, future acquisition-related costs, impacts of changes in value of any redeemable noncontrolling interest if at other than fair value, Centuri utility infrastructure expenses, differences between actual and originally expected outcomes of Centuri bid or other fixed-price construction agreements, outcomes from contract and change order negotiations, ability to successfully procure new work, impacts from work awarded or failing to be awarded from significant customers, the mix of work awarded, the amount of work awarded to Centuri following the lifting of work stoppages or reduction, the result of productivity inefficiencies from regulatory requirements or otherwise, delays in commissioning individual projects, acquisitions, and management’s plans related thereto, competition, our ability to raise capital in external financings, our ability to continue to remain within the ratios and other limits subject to our debt covenants, and ongoing evaluations in regard to goodwill and other intangible assets. In addition, the Company can provide no assurance that its discussions regarding certain trends relating to its financing and operating expenses will continue or cease to continue in future periods. For additional information on the risks associated with the Company’s business, see Item 1A. Risk Factors and Item 7A. Quantitative and Qualitative Disclosures About Market Risk in the Annual Report on Form 10-K for the year ended December 31, 2020.

All forward-looking statements in this quarterly report are made as of the date hereof, based on information available to the Company and Southwest as of the date hereof, and the Company and Southwest assume no obligation to update or revise any of its forward-looking statements, even if experience or future changes show that the indicated results or events will not be realized. We caution you not to unduly rely on any forward-looking statement(s).

ITEM 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK

See Item 7A. Quantitative and Qualitative Disclosures about Market Risk in the 2020 Annual Report on Form 10-K filed with the SEC. No material changes have occurred related to the disclosures about market risk.

ITEM 4. CONTROLS AND PROCEDURES

Management of Southwest Gas Holdings, Inc. and Southwest Gas Corporation has established disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Securities Exchange Act of 1934, as amended (the “Exchange Act”)) that are designed to provide reasonable assurance that information required to be disclosed in their respective reports filed or submitted under the Exchange Act is recorded, processed, summarized, and reported within the time periods specified in the SEC’s rules and forms and to provide reasonable assurance that such information is accumulated and communicated to management of each company, including each respective Chief Executive Officer and Chief Financial Officer, as appropriate, to allow timely decisions regarding required disclosures. A control system, no matter how well conceived and operated, can provide only reasonable, not absolute, assurance that the objectives of the control system are met. Further, the design of a control system must reflect the fact that there are resource constraints, and benefits of controls must be considered relative to their costs. Additionally, controls can be circumvented by the individual acts of some persons, by collusion of two or more people, or management override of the control. Because of the inherent limitations in a cost-effective control system, misstatements due to error or fraud may occur and may not be detected.

Based on the most recent evaluation, as of March 31, 2021, management of Southwest Gas Holdings, Inc., including the Chief Executive Officer and Chief Financial Officer, believes the Company’s disclosure controls and procedures are effective at attaining the level of reasonable assurance noted above.

There have been no changes in the Company’s internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act) during the first quarter of 2021 that have materially affected, or are likely to materially affect, the Company’s internal control over financial reporting.

Based on the most recent evaluation, as of March 31, 2021, management of Southwest Gas Corporation, including the Chief Executive Officer and Chief Financial Officer, believes Southwest’s disclosure controls and procedures are effective at attaining the level of reasonable assurance noted above.

43

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

There have been no changes in Southwest’s internal control over financial reporting (as defined in Rules 13a-15(f) and 15d-15(f) of the Exchange Act) during the first quarter of 2021 that have materially affected, or are likely to materially affect Southwest’s internal control over financial reporting.

In May 2021, the Company implemented a new customer service system, which involved replacing the legacy functionality for customer invoicing, customer service administration, and ancillary activities. The customer service system is being deployed for transactions starting in May 2021, and was not utilized in preparing the first quarter 2021 financial information. Management monitored developments related to the customer service system replacement, including working with the project team to ensure control impacts were identified and documented, in order to assist management in evaluating impacts to internal control. System integration and user acceptance testing were conducted to aid management in its evaluations. Post-implementation reviews of the system and impacted business processes are being conducted to enable management to evaluate the design and effectiveness of internal controls.

PART II - OTHER INFORMATION

ITEM 1. LEGAL PROCEEDINGS

The Company is named as a defendant in various legal proceedings. The ultimate dispositions of these proceedings are not presently determinable; however, it is the opinion of management that none of this litigation individually or in the aggregate will have a material adverse impact on the Company’s financial position or results of operations.

ITEMS 1A through 3. None.

ITEM 4. MINE SAFETY DISCLOSURES Not applicable.

ITEM 5. OTHER INFORMATION None.

ITEM 6. EXHIBITS

The following documents are filed, or furnished, as applicable, as part of this report on Form 10-Q:

Exhibit 10.01	-	Term Loan Agreement, dated as of March 23, 2021, by and among Southwest Gas Corporation, The Bank of New York Mellon, as Administrative Agent, and the lenders party, book runners and syndication agents thereto. Incorporated herein by reference to Exhibit 10.1 to Form 8-K dated March 23, 2021, File Nos. 001-37976 and 001-07850.
Exhibit 31.01	-	Section 302 Certifications–Southwest Gas Holdings, Inc.
Exhibit 31.02	-	Section 302 Certifications–Southwest Gas Corporation
Exhibit 32.01	-	Section 906 Certifications–Southwest Gas Holdings, Inc.
Exhibit 32.02	-	Section 906 Certifications–Southwest Gas Corporation
Exhibit 101.INS	-	XBRL Instance Document - the instance document does not appear in the Interactive Data File because its XBRL tags are embedded within the Inline XBRL document.
Exhibit 101SCH	-	XBRL Schema Document
Exhibit 101.CAL	-	XBRL Calculation Linkbase Document
Exhibit 101.DEF	-	XBRL Definition Linkbase Document
Exhibit 101.LAB	-	XBRL Label Linkbase Document
Exhibit 101.PRE	-	XBRL Presentation Linkbase Document
Exhibit 104	-	Cover Page Interactive Data File (embedded within the Inline XBRL document).

44

SOUTHWEST GAS HOLDINGS, INC.	Form 10-Q
SOUTHWEST GAS CORPORATION	March 31, 2021

SIGNATURES

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Southwest Gas Holdings, Inc.

(Registrant)

Dated: May 6, 2021

/s/ LORI L. COLVIN

Lori L. Colvin

Vice President/Controller and Chief Accounting Officer

Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.

Southwest Gas Corporation

(Registrant)

Dated: May 6, 2021

/s/ LORI L. COLVIN

Lori L. Colvin

Vice President/Controller and Chief Accounting Officer

45

EX-31.01

Exhibit 31.01

Certification of Southwest Gas Holdings, Inc.

I, John P. Hester, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Southwest Gas Holdings, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Dated: May 6, 2021

/s/ JOHN P. HESTER

John P. Hester

President and Chief Executive Officer

Southwest Gas Holdings, Inc.

Certification of Southwest Gas Holdings, Inc.

I, Gregory J. Peterson, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Southwest Gas Holdings, Inc.;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Dated: May 6, 2021

/s/ GREGORY J. PETERSON

Gregory J. Peterson

Senior Vice President/Chief Financial Officer

Southwest Gas Holdings, Inc.

EX-31.02

Exhibit 31.02

Certification of Southwest Gas Corporation

I, John P. Hester, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Southwest Gas Corporation;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a)designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b)designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c)evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d)disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Dated: May 6, 2021

/s/ JOHN P. HESTER

John P. Hester

President and Chief Executive Officer

Southwest Gas Corporation

Certification of Southwest Gas Corporation

I, Gregory J. Peterson, certify that:

1.I have reviewed this quarterly report on Form 10-Q of Southwest Gas Corporation;

2.Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report;

3.Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report;

4.The registrant’s other certifying officer and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have:

(a.)designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared;

(b.)designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles;

(c.)evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and

(d.)disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and

5.The registrant’s other certifying officer and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions):

(a)all significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and

(b)any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting.

Dated: May 6, 2021

/s/ GREGORY J. PETERSON

Gregory J. Peterson

Senior Vice President/Chief Financial Officer

Southwest Gas Corporation

EX-32.01

Exhibit 32.01

SOUTHWEST GAS HOLDINGS, INC.

CERTIFICATION

In connection with the periodic report of Southwest Gas Holdings, Inc. (the “Company”) on Form 10-Q for the period ended March 31, 2021 as filed with the Securities and Exchange Commission (the “Report”), I, John P. Hester, the President and Chief Executive Officer of the Company, hereby certify as of the date hereof, solely for purposes of Title 18, Chapter 63, Section 1350 of the United States Code, that to the best of my knowledge:

(1)the Report fully complies with the requirements of section 13(a) or 15(d), as applicable, of the Securities Exchange Act of 1934; and

(2)the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company at the dates and for the periods indicated.

This Certification has not been, and shall not be deemed, “filed” with the Securities and Exchange Commission.

Dated: May 6, 2021

/s/ John P. Hester

John P. Hester
President and Chief Executive Officer

SOUTHWEST GAS HOLDINGS, INC.

CERTIFICATION

In connection with the periodic report of Southwest Gas Holdings, Inc. (the “Company”) on Form 10-Q for the period ended March 31, 2021 as filed with the Securities and Exchange Commission (the “Report”), I, Gregory J. Peterson, Senior Vice President/Chief Financial Officer of the Company, hereby certify as of the date hereof, solely for purposes of Title 18, Chapter 63, Section 1350 of the United States Code, that to the best of my knowledge:

(1)the Report fully complies with the requirements of section 13(a) or 15(d), as applicable, of the Securities Exchange Act of 1934; and

(2)the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company at the dates and for the periods indicated.

This Certification has not been, and shall not be deemed, “filed” with the Securities and Exchange Commission.

Dated: May 6, 2021

/s/ Gregory J. Peterson

Gregory J. Peterson
Senior Vice President/Chief Financial Officer

EX-32.02

Exhibit 32.02

SOUTHWEST GAS CORPORATION

CERTIFICATION

In connection with the periodic report of Southwest Gas Corporation on Form 10-Q for the period ended March 31, 2021 as filed with the Securities and Exchange Commission (the “Report”), I, John P. Hester, the President and Chief Executive Officer of Southwest Gas Corporation, hereby certify as of the date hereof, solely for purposes of Title 18, Chapter 63, Section 1350 of the United States Code, that to the best of my knowledge:

(1)the Report fully complies with the requirements of section 13(a) or 15(d), as applicable, of the Securities Exchange Act of 1934; and

(2)the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of Southwest Gas Corporation at the dates and for the periods indicated.

This Certification has not been, and shall not be deemed, “filed” with the Securities and Exchange Commission.

Dated: May 6, 2021

/s/ John P. Hester

John P. Hester
President and Chief Executive Officer

SOUTHWEST GAS CORPORATION

CERTIFICATION

In connection with the periodic report of Southwest Gas Corporation on Form 10-Q for the period ended March 31, 2021 as filed with the Securities and Exchange Commission (the “Report”), I, Gregory J. Peterson, Senior Vice President/Chief Financial Officer of Southwest Gas Corporation, hereby certify as of the date hereof, solely for purposes of Title 18, Chapter 63, Section 1350 of the United States Code, that to the best of my knowledge:

(1)the Report fully complies with the requirements of section 13(a) or 15(d), as applicable, of the Securities Exchange Act of 1934; and

(2)the information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of Southwest Gas Corporation at the dates and for the periods indicated.

This Certification has not been, and shall not be deemed, “filed” with the Securities and Exchange Commission.

Dated: May 6, 2021

/s/ Gregory J. Peterson

Gregory J. Peterson
Senior Vice President/Chief Financial Officer

XML

Cover - shares	3 Months Ended
	Mar. 31, 2021	Apr. 30, 2021
Entity Information [Line Items]
Document Type	10-Q
Document Quarterly Report	true
Document Period End Date	Mar. 31, 2021
Document Transition Report	false
Entity File Number	001-37976
Entity Registrant Name	Southwest Gas Holdings, Inc.
Entity Incorporation, State or Country Code	DE
Entity Tax Identification Number	81-3881866
Entity Address, Address Line One	8360 S. Durango Drive
Entity Address, Address Line Two	Post Office Box 98510
Entity Address, City or Town	Las Vegas,
Entity Address, State or Province	NV
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 Current Reporting Status	Yes
Entity Interactive Data Current	Yes
Entity Filer Category	Large Accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Shell Company	false
Entity Common Stock, Shares Outstanding		58,001,396
Entity Central Index Key	0001692115
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Current Fiscal Year End Date	--12-31
Southwest Gas Corporation
Entity Information [Line Items]
Document Type	10-Q
Entity File Number	1-7850
Entity Registrant Name	Southwest Gas Corporation
Entity Incorporation, State or Country Code	CA
Entity Tax Identification Number	88-0085720
Entity Address, Address Line One	8360 S. Durango Drive
Entity Address, Address Line Two	Post Office Box 98510
Entity Address, City or Town	Las Vegas,
Entity Address, State or Province	NV
Entity Address, Postal Zip Code	89193-8510
City Area Code	(702)
Local Phone Number	876-7237
Entity Filer Category	Non-accelerated Filer
Entity Small Business	false
Entity Emerging Growth Company	false
Entity Central Index Key	0000092416
Document Fiscal Year Focus	2021
Document Fiscal Period Focus	Q1
Amendment Flag	false
Current Fiscal Year End Date	--12-31

XML

CONDENSED CONSOLIDATED BALANCE SHEETS - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Utility plant:
Gas plant	$ 8,479,295	$ 8,384,000
Less: accumulated depreciation	(2,453,924)	(2,419,348)
Construction work in progress	215,395	211,429
Net utility plant	6,240,766	6,176,081
Other property and investments	842,672	834,245
Current assets:
Cash and cash equivalents	92,345	83,352
Accounts receivable, net of allowances	479,184	522,172
Accrued utility revenue	50,500	82,400
Income taxes receivable, net	6,523	10,884
Deferred purchased gas costs	238,886	2,053
Prepaid and other current assets	133,466	170,152
Total current assets	1,000,904	871,013
Noncurrent assets:
Goodwill	346,553	345,184
Deferred income taxes	563	455
Deferred charges and other assets	497,187	508,875
Total noncurrent assets	844,303	854,514
Total assets	8,928,645	8,735,853
Capitalization:
Common stock, $1 par (authorized - 120,000,000 shares; issued and outstanding - 57,995,563 and 57,192,925 shares)	59,625	58,823
Additional paid-in capital	1,660,108	1,609,155
Accumulated other comprehensive loss, net	(58,388)	(61,003)
Retained earnings	1,112,377	1,067,978
Total equity	2,773,722	2,674,953
Redeemable noncontrolling interest	205,286	165,716
Long-term debt, less current maturities	2,696,570	2,732,200
Total capitalization	5,675,578	5,572,869
Current liabilities:
Current maturities of long-term debt	67,334	40,433
Short-term debt	310,000	107,000
Accounts payable	182,805	231,301
Customer deposits	67,121	67,920
Income taxes payable, net	19,356	12,556
Accrued general taxes	72,103	48,640
Accrued interest	34,571	20,536
Deferred purchased gas costs	0	54,636
Other current liabilities	282,745	328,945
Total current liabilities	1,036,035	911,967
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	671,574	647,453
Accumulated removal costs	407,000	404,000
Other deferred credits and other long-term liabilities	1,138,458	1,199,564
Total deferred income taxes and other credits	2,217,032	2,251,017
Total capitalization and liabilities	8,928,645	8,735,853
Southwest Gas Corporation
Utility plant:
Gas plant	8,479,295	8,384,000
Less: accumulated depreciation	(2,453,924)	(2,419,348)
Construction work in progress	215,395	211,429
Net utility plant	6,240,766	6,176,081
Other property and investments	146,338	143,611
Current assets:
Cash and cash equivalents	49,795	41,070
Accounts receivable, net of allowances	174,492	146,861
Accrued utility revenue	50,500	82,400
Income taxes receivable, net	0	11,155
Deferred purchased gas costs	238,886	2,053
Prepaid and other current assets	118,397	152,748
Total current assets	632,070	436,287
Noncurrent assets:
Goodwill	10,095	10,095
Deferred charges and other assets	481,184	490,562
Total noncurrent assets	491,279	500,657
Total assets	7,510,453	7,256,636
Capitalization:
Common stock, $1 par (authorized - 120,000,000 shares; issued and outstanding - 57,995,563 and 57,192,925 shares)	49,112	49,112
Additional paid-in capital	1,458,344	1,410,345
Accumulated other comprehensive loss, net	(59,343)	(61,135)
Retained earnings	926,011	835,146
Total equity	2,374,124	2,233,468
Long-term debt, less current maturities	2,413,588	2,438,206
Total capitalization	4,787,712	4,671,674
Current liabilities:
Current maturities of long-term debt	25,000	0
Short-term debt	267,000	57,000
Accounts payable	117,471	161,646
Customer deposits	67,121	67,920
Income taxes payable, net	7,232	0
Accrued general taxes	72,103	48,640
Accrued interest	34,532	20,495
Deferred purchased gas costs	0	54,636
Payable to parent	90	142
Other current liabilities	141,167	146,046
Total current liabilities	731,716	556,525
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits, net	596,617	581,100
Accumulated removal costs	407,000	404,000
Other deferred credits and other long-term liabilities	987,408	1,043,337
Total deferred income taxes and other credits	1,991,025	2,028,437
Total capitalization and liabilities	$ 7,510,453	$ 7,256,636

XML

CONDENSED CONSOLIDATED BALANCE SHEETS (Parenthetical) - $ / shares	Mar. 31, 2021	Dec. 31, 2020
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)	57,995,563	57,192,925
Common stock, outstanding (in shares)	57,995,563	57,192,925

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CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Operating revenues:
Gas operating revenues	$ 521,932	$ 502,827	$ 1,369,690	$ 1,351,089
Utility infrastructure services revenues	535,520	504,793	1,369,878	1,337,907
Total operating revenues	885,907	836,320	3,348,460	3,122,698
Operating expenses:
Net cost of gas sold	156,021	160,821	338,037	353,381
Operations and maintenance	106,690	103,781	411,025	421,686
Depreciation and amortization	93,442	87,653	337,816	313,351
Taxes other than income taxes	20,687	16,378	67,769	62,500
Utility infrastructure services expenses	335,614	319,314	1,745,729	1,592,076
Total operating expenses	712,454	687,947	2,900,376	2,742,994
Operating income	173,453	148,373	448,084	379,704
Other income and (expenses):
Net interest deductions	(23,964)	(28,380)	(107,061)	(111,209)
Other income (deductions)	448	(20,770)	14,429	(17,524)
Total other income and (expenses)	(23,516)	(49,150)	(92,632)	(128,733)
Income before income taxes	149,937	99,223	355,452	250,971
Income tax expense	31,092	26,218	70,627	56,703
Net income	118,845	73,005	284,825	194,268
Net income attributable to noncontrolling interest	1,552	463	7,750	2,599
Net income attributable to Southwest Gas Holdings, Inc.	$ 117,293	$ 72,542	$ 277,075	$ 191,669
Earnings per share:
Basic (in USD per share)	$ 2.04	$ 1.31	$ 4.90	$ 3.50
Diluted (in USD per share)	$ 2.03	$ 1.31	$ 4.89	$ 3.50
Weighted average shares:
Basic (in shares)	57,600	55,310	56,564	54,726
Diluted (in shares)	57,679	55,363	56,649	54,792
Southwest Gas Corporation
Operating revenues:
Gas operating revenues	$ 521,932	$ 502,827	$ 1,369,690	$ 1,351,089
Operating expenses:
Net cost of gas sold	156,021	160,821	338,037	353,381
Operations and maintenance	106,135	103,088	409,429	419,720
Depreciation and amortization	68,698	64,725	239,268	222,733
Taxes other than income taxes	20,687	16,378	67,769	62,500
Total operating expenses	351,541	345,012	1,054,503	1,058,334
Operating income	170,391	157,815	315,187	292,755
Other income and (expenses):
Net interest deductions	(22,166)	(25,058)	(98,256)	(96,985)
Other income (deductions)	550	(20,536)	14,496	(16,965)
Total other income and (expenses)	(21,616)	(45,594)	(83,760)	(113,950)
Income before income taxes	148,775	112,221	231,427	178,805
Income tax expense	30,060	28,622	37,193	35,424
Net income	118,715	83,599	194,234	143,381
Net income attributable to Southwest Gas Holdings, Inc.	118,715	83,599	194,234	143,381
Centuri
Operating revenues:
Utility infrastructure services revenues	$ 363,975	$ 333,493	$ 1,978,770	$ 1,771,609

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CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Net income	$ 118,845	$ 73,005	$ 284,825	$ 194,268
Defined benefit pension plans:
Net actuarial loss	0	0	(43,730)	(54,026)
Amortization of prior service cost	182	220	840	945
Amortization of net actuarial loss	8,474	7,188	30,037	20,513
Prior service cost	0	0	0	(1,426)
Regulatory adjustment	(7,277)	(6,380)	4,753	25,760
Net defined benefit pension plans	1,379	1,028	(8,100)	(8,234)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	413	636	2,244	2,542
Net forward-starting interest rate swaps	413	636	2,244	2,542
Foreign currency translation adjustments	823	(4,005)	6,541	(2,758)
Total other comprehensive income (loss), net of tax	2,615	(2,341)	685	(8,450)
Comprehensive income	121,460	70,664	285,510	185,818
Comprehensive income attributable to noncontrolling interest	1,552	463	7,750	2,599
Comprehensive income attributable to Southwest Gas Holdings, Inc.	119,908	70,201	277,760	183,219
Southwest Gas Corporation
Net income	118,715	83,599	194,234	143,381
Defined benefit pension plans:
Net actuarial loss	0	0	(43,730)	(54,026)
Amortization of prior service cost	182	220	840	945
Amortization of net actuarial loss	8,474	7,188	30,037	20,513
Prior service cost	0	0	0	(1,426)
Regulatory adjustment	(7,277)	(6,380)	4,753	25,760
Net defined benefit pension plans	1,379	1,028	(8,100)	(8,234)
Forward-starting interest rate swaps (“FSIRS”):
Amounts reclassified into net income	413	636	2,244	2,542
Net forward-starting interest rate swaps	413	636	2,244	2,542
Total other comprehensive income (loss), net of tax	1,792	1,664	(5,856)	(5,692)
Comprehensive income	$ 120,507	$ 85,263	$ 188,378	$ 137,689

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CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$ 118,845	$ 73,005	$ 284,825	$ 194,268
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	93,442	87,653	337,816	313,351
Deferred income taxes	23,326	25,309	48,734	54,548
Changes in current assets and liabilities:
Accounts receivable, net of allowances	42,892	45,837	(51,717)	7,154
Accrued utility revenue	31,900	31,000	(2,400)	(1,100)
Deferred purchased gas costs	(291,469)	10,155	(265,385)	19,527
Accounts payable	(41,147)	(60,723)	11,882	(49,945)
Accrued taxes	34,636	30,377	19,430	10,220
Other current assets and liabilities	(5,255)	76,453	25,719	102,742
Gains on sale of equipment	(1,509)	(28)	(3,329)	(5,268)
Changes in undistributed stock compensation	3,658	2,816	7,956	6,524
Equity AFUDC	(981)	(1,061)	(4,644)	(4,262)
Changes in deferred charges and other assets	(10,379)	6,495	(49,465)	1,772
Changes in other liabilities and deferred credits	(50,416)	(55,722)	(57,365)	(65,704)
Net cash provided by (used in) operating activities	(52,457)	271,566	302,057	583,827
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(152,709)	(210,655)	(767,159)	(938,141)
Acquisition of businesses, net of cash acquired	0	0	0	(47,638)
Changes in customer advances	4,286	5,434	12,885	21,357
Other	3,563	4,430	8,136	19,321
Net cash used in investing activities	(144,860)	(200,791)	(746,138)	(945,101)
CASH FLOW FROM FINANCING ACTIVITIES:
Issuance of common stock, net	48,990	3,148	185,087	135,215
Dividends paid	(32,619)	(30,006)	(128,117)	(118,531)
Issuance of long-term debt, net	10,659	99,978	573,058	601,908
Retirement of long-term debt	(21,228)	(75,168)	(302,466)	(257,797)
Change in short-term debt	203,000	(54,000)	153,000	(31,000)
Withholding remittance - share-based compensation	(1,242)	(2,736)	(1,242)	(2,756)
Other	(1,353)	(250)	(4,505)	(1,615)
Net cash provided by (used in) financing activities	206,207	(59,034)	474,815	325,424
Effects of currency translation on cash and cash equivalents	103	(315)	646	(222)
Change in cash and cash equivalents	8,993	11,426	31,380	(36,072)
Cash and cash equivalents at beginning of period	83,352	49,539	60,965	97,037
Cash and cash equivalents at end of period	92,345	60,965	92,345	60,965
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	8,303	13,073	100,412	99,481
Income taxes paid (received), net	1,651	(20,064)	10,764	(17,766)
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	118,715	83,599	194,234	143,381
Adjustments to reconcile net income to net cash provided by (used in) operating activities:
Depreciation and amortization	68,698	64,725	239,268	222,733
Deferred income taxes	14,952	7,707	52,242	15,118
Changes in current assets and liabilities:
Accounts receivable, net of allowances	(27,631)	1,975	(25,673)	21,652
Accrued utility revenue	31,900	31,000	(2,400)	(1,100)
Deferred purchased gas costs	(291,469)	10,155	(265,385)	19,527
Accounts payable	(33,076)	(41,899)	18,441	(29,798)
Accrued taxes	41,851	53,335	(13,011)	33,526
Other current assets and liabilities	41,018	99,257	(9,694)	106,803
Changes in undistributed stock compensation	2,908	2,496	5,706	5,045
Equity AFUDC	(981)	(1,061)	(4,644)	(4,262)
Changes in deferred charges and other assets	(13,535)	3,658	(61,484)	(9,871)
Changes in other liabilities and deferred credits	(48,782)	(55,910)	(58,008)	(66,294)
Net cash provided by (used in) operating activities	(95,432)	259,037	69,592	456,460
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(128,544)	(173,353)	(647,407)	(788,465)
Changes in customer advances	4,285	5,433	12,885	21,356
Other	(121)	(31)	681	(48)
Net cash used in investing activities	(124,380)	(167,951)	(633,841)	(767,157)
CASH FLOW FROM FINANCING ACTIVITIES:
Contributions from parent	45,984	50,000	173,906	187,094
Dividends paid	(26,000)	(25,200)	(105,300)	(97,600)
Issuance of long-term debt, net	0	0	446,508	297,222
Retirement of long-term debt	0	0	(125,000)	0
Change in short-term debt	210,000	(97,000)	170,000	(91,000)
Withholding remittance - share-based compensation	(1,242)	(2,736)	(1,242)	(2,756)
Other	(205)	(115)	(1,352)	(887)
Net cash provided by (used in) financing activities	228,537	(75,051)	557,520	292,073
Change in cash and cash equivalents	8,725	16,035	(6,729)	(18,624)
Cash and cash equivalents at beginning of period	41,070	40,489	56,524	75,148
Cash and cash equivalents at end of period	49,795	56,524	49,795	56,524
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	6,952	10,204	93,474	87,277
Income taxes paid (received), net	$ 0	$ (22,962)	$ 3,359	$ 700

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CONDENSED CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Total	Southwest Gas Corporation	Common Stock	Common Stock 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	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	$ 1,229,083	$ (56,732)	$ (55,151)	$ 1,039,072	$ 782,108
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuances (in shares)			119,000
Common stock issuances			$ 119		3,474
Foreign currency exchange translation adjustment							(4,005)
Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax							1,028	1,028
FSIRS amounts reclassified to net income, net of tax	$ 636	$ 636					636	636
Net income									72,542	83,599
Share-based compensation						125				(364)
Contributions from Southwest Gas Holdings, Inc.						50,000
Dividends declared									(31,813)	(25,900)
Redemption value adjustments									0
Ending balance (in shares) at Mar. 31, 2020			55,126,000	47,482,000
Ending balance at Mar. 31, 2020		2,114,276	$ 56,756	$ 49,112	1,470,411	1,279,208	(59,073)	(53,487)	1,079,801	839,443	$ 2,547,895
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share (in USD per share)	$ 0.57
FSIRS amounts reclassified to net income, net of tax	$ 2,244	2,244
Ending balance (in shares) at Mar. 31, 2021	57,995,563		57,995,000	47,482,000
Ending balance at Mar. 31, 2021		2,374,124	$ 59,625	$ 49,112	1,660,108	1,458,344	(58,388)	(59,343)	1,112,377	926,011	2,773,722
Beginning balance (in shares) at Dec. 31, 2020	57,192,925		57,193,000
Beginning balance at Dec. 31, 2020			$ 58,823		1,609,155	1,410,345	(61,003)	(61,135)	1,067,978	835,146
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Common stock issuances (in shares)			802,000
Common stock issuances			$ 802		50,953
Foreign currency exchange translation adjustment							823
Net actuarial gain arising during period, less amortization of unamortized benefit plan cost, net of tax							1,379	1,379
FSIRS amounts reclassified to net income, net of tax	$ 413	413					413	413
Net income									117,293	118,715
Share-based compensation						2,015				(350)
Contributions from Southwest Gas Holdings, Inc.						45,984
Dividends declared									(34,876)	(27,500)
Redemption value adjustments	$ 38,018								(38,018)
Ending balance (in shares) at Mar. 31, 2021	57,995,563		57,995,000	47,482,000
Ending balance at Mar. 31, 2021		$ 2,374,124	$ 59,625	$ 49,112	$ 1,660,108	$ 1,458,344	$ (58,388)	$ (59,343)	$ 1,112,377	$ 926,011	$ 2,773,722
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Dividends declared per share (in USD per share)	$ 0.595

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Background, Organization, and Summary of Significant Accounting Policies

3 Months Ended

Mar. 31, 2021

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. Southwest Gas Holdings, Inc. is a holding company, owning all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas operations” segment) and all of the shares of common stock of Centuri Group, Inc. (“Centuri,” or the “utility infrastructure services” 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 operations segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures.

Centuri is a comprehensive utility infrastructure services enterprise dedicated to delivering a diverse array of solutions to North America’s gas and electric providers. Centuri derives revenue primarily from installation, replacement, repair, and maintenance of energy distribution systems. Centuri operations are generally conducted under the business names of NPL Construction Co. (“NPL”), NPL Canada Ltd. (“NPL Canada”), New England Utility Constructors, Inc. (“Neuco”), and Linetec Services, LLC (“Linetec”). Utility infrastructure services activity is seasonal in most of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern United States (“U.S.”) and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round.

Basis of Presentation. The condensed consolidated financial statements of Southwest Gas Holdings, Inc. and subsidiaries (the “Company”) and Southwest included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. No substantive change has occurred with regard to the Company’s business segments on the whole.

The preparation of the condensed consolidated financial statements 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. In the opinion of management, all adjustments, consisting of normal recurring items and estimates necessary for a fair depiction of results for the interim periods, have been made. In association with the novel Coronavirus (“COVID-19”) pandemic environment, utility operations, and to a large extent, utility infrastructure services, have been deemed “essential services.” Management has considered the impact of the pandemic and adjusted certain estimates, where relevant, used in the preparation of the condensed consolidated financial statements.

These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the 2020 Annual Report to Stockholders, which is incorporated by reference into the 2020 Form 10-K.

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 in valuing cash and cash equivalents, long-term debt outstanding, and assets of the qualified pension plan and postretirement benefit plans required to be recorded and/or disclosed at fair value.

Other Property and Investments. Other property and investments on the Condensed Consolidated Balance Sheets includes:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Southwest Gas Corporation:
Net cash surrender value of COLI policies	$	143,618	$	140,874
Other property	2,720		2,737
Total Southwest Gas Corporation	146,338		143,611
Centuri property, equipment, and intangibles	1,106,855		1,089,414
Centuri accumulated provision for depreciation and amortization	(439,126)		(422,741)
Other property and investments	28,605		23,961
Total Southwest Gas Holdings, Inc.	$	842,672	$	834,245

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. Balances reflect impacts of equity and fixed-income securities underlying the cash surrender values at each reporting date; however, ultimately, only the insurance proceeds are ever actually received, due to management’s intent to hold the policies to maturity.

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 Southwest and the Company include money market fund investments totaling approximately $40,000 for each entity at March 31, 2021 and December 31, 2020, respectively, which fall within Level 2 of the fair value hierarchy, due to the asset valuation methods used by money market funds.

Typical non-cash investing activities include customer advances applied as contributions toward utility construction activity, and capital expenditures that were not paid as of period-end reporting dates, but rather included in accounts payable. Typical activities that represent aspects of both non-cash investing and non-cash financing activities relate to right-of-use assets obtained in exchange for lease liabilities (including, at times, lease terminations and modifications). Amounts related to these collective activities were immaterial for the periods presented herein.

Intercompany Transactions. Centuri recognizes revenues generated from contracts with Southwest (see Note 7 – Segment Information). The accounts receivable balance, revenues, and associated profits are included in the condensed consolidated financial statements of the Company and Southwest and were not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities.

Accounts Receivable, net of 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 no billing due dates customarily extending beyond one month, with customers’ credit worthiness assessed upon account creation by evaluation of other utility service and related payment history. Due to the ongoing COVID-19 pandemic, Southwest continued the moratorium initiated in March 2020 on disconnection of natural gas service for non-payment, but recommenced assessing late fees in Nevada and Arizona in April 2021, with late fees in California expected to recommence in the latter half of 2021. Southwest is actively working with customers experiencing financial hardship by means of flexible payment options. Management continues to monitor expected credit losses in light of the evolving impact of COVID-19. The allowance as of March 31, 2021 reflects the expected impact from the pandemic on balances as of that date, including consideration of customers’ ability to pay currently and once the moratorium on disconnections is lifted.

Utility infrastructure services contracts 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 has not been significantly impacted, nor does it anticipate it will experience significant difficulty in collecting amounts due, as a result of the current environment surrounding COVID-19 given the nature of its customers.

Activity between periods in the allowance for uncollectibles and the balances as of the periods presented within the Company’s and Southwest’s financial statements were not material to the condensed consolidated financial statements overall.

Deferred Purchased Gas Costs. The various regulatory commissions have established procedures to enable Southwest to adjust its 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.

In mid-February 2021, the central U.S. (from south Texas to North Dakota and the eastern Rocky Mountains) experienced extreme cold temperatures, which increased natural gas demand and caused supply issues due to wellhead freeze-offs, power outages, or other adverse operating conditions upstream of Southwest’s distribution systems. These conditions caused daily natural gas prices to reach unprecedented levels. During this time, Southwest secured natural gas supplies, albeit at substantially higher prices, maintaining service to its customers. The incremental cost for these supplies was approximately $250 million, funded using a 364-day $250 million Bank Term Loan executed in March 2021 (see Note 5 – Debt). The incremental gas costs are expected to be collected from customers through the purchased gas adjustment (“PGA”) mechanisms.

Following the extreme weather event, an interstate transmission pipeline company billed Southwest, in addition to customary transmission costs, $65 million for pipeline imbalance charges, allegedly incurred during the period of the pipeline’s critical operation condition. However, Southwest has formally disputed these imbalance charges and believes that no amounts are due to the pipeline. Consequently, Southwest has not recognized this charge. Pipeline transmission costs, including periodic imbalance charges, are components of the cost of gas recovered from customers through the PGA and similar mechanisms.

Prepaid and other current assets. Prepaid and other current assets includes gas pipe materials and operating supplies of $47 million at March 31, 2021 and $50 million at December 31, 2020 (carried at weighted average cost).

Goodwill. Goodwill is assessed as of October 1st each year for impairment, or more frequently, if circumstances indicate an impairment to the carrying value of goodwill may have occurred. Management of the Company and Southwest considered its reporting units and segments and determined that its segments and reporting units remain consistent between periods presented below, and that no change was necessary with regard to the level at which goodwill is assessed for impairment. Since December 31, 2020, management also qualitatively assessed whether events during the first three months of 2021 may have resulted in conditions whereby the carrying value of goodwill was higher than its fair value, which if the case, could be an indication of a permanent impairment. Through this assessment, no such condition was believed to have existed and therefore, no impairment was deemed to have occurred. Goodwill on Southwest’s and the Company’s Condensed Consolidated Balance Sheets includes:

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Total Company
December 31, 2020	$	10,095	$	335,089	$	345,184
Foreign currency translation adjustment	—		1,369		1,369
March 31, 2021	$	10,095	$	336,458	$	346,553

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 amounts payable under regulatory mechanisms, customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities. Other current liabilities for the Company includes $34.5 million and $32.6 million of dividends declared, as well as $37 million and $25.2 million of accrued property taxes, as of March 31, 2021 and December 31, 2020, respectively.

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

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Southwest Gas Corporation - natural gas operations segment:
Change in COLI policies	$	2,700	$	(15,500)	$	27,400	$	(5,700)
Interest income	716		1,388		3,343		6,147
Equity AFUDC	981		1,061		4,644		4,262
Other components of net periodic benefit cost	(3,505)		(5,005)		(18,522)		(16,299)
Miscellaneous income and (expense)	(342)		(2,480)		(2,369)		(5,375)
Southwest Gas Corporation - total other income (deductions)	550		(20,536)		14,496		(16,965)
Utility infrastructure services segment:
Foreign transaction gain (loss)	(3)		(10)		(9)		5
Miscellaneous income and (expense)	(99)		(232)		(58)		(656)
Centuri - total other income (deductions)	(102)		(242)		(67)		(651)
Corporate and administrative	—		8		—		92
Consolidated Southwest Gas Holdings, Inc. - total other income (deductions)	$	448	$	(20,770)	$	14,429	$	(17,524)

Included in the table above is the change in cash surrender values of COLI policies (including net death benefits recognized). Current tax regulations provide for tax-free treatment of life insurance (death benefit) proceeds. Therefore, changes in the cash surrender values of COLI policies, as they progress towards the ultimate death benefits, are also recorded without tax consequences. Refer to Other Property and Investments above and also to Note 2 – Components of Net Periodic Benefit Cost.

Redeemable Noncontrolling Interest. 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.

Significant changes in the value of the redeemable noncontrolling interest, above a floor established at the acquisition 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 redeemable noncontrolling interest increased by approximately $38 million during the first quarter of 2021. Adjustment to the redemption value also impacts retained earnings, as reflected in the Company’s Condensed Consolidated Statement of Equity, but does not impact net income. The following depicts the change to the balance of the redeemable noncontrolling interest:

(Thousands of dollars):	Redeemable Noncontrolling Interest
Balance, December 31, 2020	$	165,716
Net income attributable to redeemable noncontrolling interest	1,552
Redemption value adjustment	38,018
Balance, March 31, 2021	$	205,286

Earnings Per Share. Basic earnings per share (“EPS”) in each period of this report were calculated by dividing net income 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). 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:

	Three Months Ended March 31,		Twelve Months Ended March 31,
(In thousands)	2021	2020	2021	2020
Weighted average basic shares	57,600	55,310	56,564	54,726
Effect of dilutive securities:
Management Incentive Plan shares	—	—	—	9
Restricted stock units (1)	79	53	85	57
Weighted average diluted shares	57,679	55,363	56,649	54,792

(1) The number of securities included 75,000 and 50,000 performance shares during the three months ending March 31, 2021 and 2020, and 76,000 and 48,000 performance shares during the twelve months ending March 31, 2021 and 2020, respectively, the total of which was derived by assuming that target performance will be achieved during the relevant performance period.

Recent Accounting Standards Updates.

Accounting pronouncements adopted in 2021:

In December 2019, the Financial Accounting Standards Board (the “FASB”) issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” The update simplifies the accounting for income taxes by removing certain exceptions to the general principles, as well as improving consistent application in Topic 740 by clarifying and amending existing guidance. The Company and Southwest adopted the update in the first quarter of 2021, the impact of which was not material to the condensed consolidated financial statements of the Company or Southwest.

Recently issued accounting pronouncements that will be effective after 2021:

In March 2020, the FASB issued 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 Topic 848) to replace a reference rate affected by such reform. The update applies only to contracts and hedging relationships that reference the London Interbank Offered Rate (“LIBOR”) or another 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. Management will 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 5 – 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 update is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years; early adoption is permitted. Management is evaluating what impacts, if any, this update might have on the Company’s consolidated financial statements and disclosures.

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Components of Net Periodic Benefit Cost

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Components of Net Periodic Benefit Cost

Note 2 – Components of Net Periodic Benefit Cost

Southwest has a noncontributory qualified retirement plan with defined benefits covering substantially all employees and a separate unfunded supplemental retirement plan (“SERP”) which is limited to officers. Southwest also provides postretirement benefits other than pensions (“PBOP”) to its qualified retirees for health care, dental, and life insurance.

The service cost component of net periodic benefit costs included in the table below is a component of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of service cost 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 utility plant, and deferred charges and other assets for both the Company and Southwest. The other components of net periodic benefit cost are reflected in Other income (deductions) on the Condensed Consolidated Statements of Income of each entity.

	Qualified Retirement Plan
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	10,290	$	8,574	$	36,015	$	27,972
Interest cost	10,108		11,388		44,275		48,142
Expected return on plan assets	(18,088)		(16,324)		(67,060)		(61,507)
Amortization of net actuarial loss	10,489		9,007		37,507		25,774
Net periodic benefit cost	$	12,799	$	12,645	$	50,737	$	40,381
	SERP
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	131	$	98	$	422	$	298
Interest cost	358		401		1,561		1,721
Amortization of net actuarial loss	660		451		2,014		1,216
Net periodic benefit cost	$	1,149	$	950	$	3,997	$	3,235
	PBOP
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	423	$	396	$	1,608	$	1,353
Interest cost	548		645		2,485		2,929
Expected return on plan assets	(810)		(852)		(3,366)		(3,219)
Amortization of prior service costs	240		289		1,106		1,243
Net periodic benefit cost	$	401	$	478	$	1,833	$	2,306

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Revenue

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Revenue

Note 3 – Revenue

The following information about the Company’s revenues is presented by segment. Southwest encompasses the natural gas operations segment and Centuri encompasses the utility infrastructure services segment.

Natural Gas Operations Segment:

Gas operating revenues on the Condensed Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below, disaggregated by customer type, and various categories of revenue:

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Residential	$	403,143	$	378,555	$	983,108	$	934,115
Small commercial	81,398		82,463		220,476		241,970
Large commercial	12,673		12,667		44,639		47,640
Industrial/other	13,770		6,702		33,310		22,298
Transportation	24,536		24,406		88,345		91,884
Revenue from contracts with customers	535,520		504,793		1,369,878		1,337,907
Alternative revenue program revenues (deferrals)	(16,373)		(3,765)		(468)		5,668
Other revenues (1)	2,785		1,799		280		7,514
Total Gas operating revenues	$	521,932	$	502,827	$	1,369,690	$	1,351,089

(1) 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 customer rates expected to be returned to customers in future periods. Late fees and certain other fees were reduced, for the three- and twelve-month periods ended March 31, 2021, due to a moratorium on late fees and disconnection for nonpayment during the COVID-19 pandemic.

Utility Infrastructure Services Segment:

The following tables display Centuri’s revenue, reflected as Utility infrastructure services revenues on the Condensed Consolidated Statements of Income of the Company, representing revenue from contracts with customers disaggregated by service and contract types:

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Service Types:
Gas infrastructure services	$	221,837	$	217,709	$	1,265,288	$	1,258,790
Electric power infrastructure services	93,961		72,320		433,467		267,736
Other	48,177		43,464		280,015		245,083
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Contract Types:
Master services agreement	$	293,680	$	263,545	$	1,520,144	$	1,411,267
Bid contract	70,295		69,948		458,626		360,342
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609
Unit price contracts	$	234,449	$	243,136	$	1,347,953	$	1,387,706
Fixed price contracts	34,594		27,545		164,750		101,931
Time and materials contracts	94,932		62,812		466,067		281,972
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609

The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract asset), which are both included within Accounts receivable, net of allowances, as well as amounts billed in excess of revenue earned on contracts (contract liability), which are included in Other current liabilities as of March 31, 2021 and December 31, 2020 on the Company’s Condensed Consolidated Balance Sheets:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Contracts receivable, net	$	197,357	$	278,316
Revenue earned on contracts in progress in excess of billings	107,336		96,996
Amounts billed in excess of revenue earned on contracts	5,985		4,507

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 for billing at the reporting date. These contract assets are transferred to contracts receivable when the rights become unconditional. 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, 2020 to March 31, 2021 is due to revenue recognized of $4.5 million that was included in this item as of January 1, 2021, after which time it became earned and the balance was reduced, and to increases due to cash 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 uses the practical expedient applicable to such contracts and does not consider/compute an interest component based on the time value of money. Further, because of the short duration of these contracts, Centuri 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 March 31, 2021, Centuri had 18 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 March 31, 2021 was $48.7 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 are provided by the customer.

Utility infrastructure services contracts receivable consists of the following:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Billed on completed contracts and contracts in progress	$	193,042	$	273,778
Other receivables	5,789		6,692
Contracts receivable, gross	198,831		280,470
Allowance for doubtful accounts	(1,474)		(2,154)
Contracts receivable, net	$	197,357	$	278,316

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Common Stock

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

Common Stock

Note 4 – Common Stock

Only 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 stock awards to be issued in shares of Southwest Gas Holdings, Inc.

On May 8, 2019, the Company filed with the SEC an automatic shelf registration statement on Form S-3 (File No. 333-231297), which became effective upon filing, for the offer and sale of up to $300 million of common stock from time to time in at-the-market offerings under the prospectus included therein and in accordance with the Sales Agency Agreement, dated May 8, 2019, between the Company and BNY Mellon Capital Markets, LLC (the “Equity Shelf Program”). The following table provides the activity under the Equity Shelf Program for the three-month and life-to-date periods ended March 31, 2021:

	Three Months Ended		Life-To-Date Ended
	March 31, 2021
Gross proceeds	$	46,448,484	$	299,999,974
Less: agent commissions	(464,485)		(3,000,000)
Net proceeds	$	45,983,999	$	296,999,974
Number of shares sold	705,957		4,102,414
Weighted average price per share	$	65.80	$	73.13

During the quarter ended March 31, 2021, the Company sold essentially all of the remaining common stock available for sale 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.

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 for the offer and sale of up to $500 million of common stock from time to time in a new at-the-market offering program. The shares will be issued pursuant to the Company’s automatic shelf registration statement on Form S-3 (File No. 333-251074), which became effective upon filing with the SEC on December 2, 2020.

During the three months ended March 31, 2021, the Company issued approximately 47,000 shares of common stock through the Restricted Stock/Unit Plan and Omnibus Incentive Plan.

Additionally, during the three months ended March 31, 2021, the Company issued 49,500 shares of common stock through the Dividend Reinvestment and Stock Purchase Plan, raising approximately $3.1 million.

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Debt

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

Debt

Note 5 – Debt

Long-Term Debt

Long-term debt is recognized in the Company’s and Southwest’s Condensed Consolidated Balance Sheets generally at the carrying value of the obligations outstanding. Details surrounding the fair value, as described in Note 1 – Background, Organization, and Summary of Significant Accounting Policies, and individual carrying values of instruments are provided in the table that follows.

	March 31, 2021				December 31, 2020
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
(Thousands of dollars)
Southwest Gas Corporation:
Debentures:
Notes, 6.1%, due 2041	$	125,000	$	160,651	$	125,000	$	174,858
Notes, 3.875%, due 2022	250,000		256,693		250,000		258,825
Notes, 4.875%, due 2043	250,000		288,500		250,000		317,190
Notes, 3.8%, due 2046	300,000		306,261		300,000		347,046
Notes, 3.7%, due 2028	300,000		324,069		300,000		344,553
Notes, 4.15%, due 2049	300,000		324,183		300,000		370,278
Notes, 2.2%, due 2030	450,000		438,912		450,000		474,552
8% Series, due 2026	75,000		95,894		75,000		99,723
Medium-term notes, 7.78% series, due 2022	25,000		26,201		25,000		26,663
Medium-term notes, 7.92% series, due 2027	25,000		32,138		25,000		33,802
Medium-term notes, 6.76% series, due 2027	7,500		9,127		7,500		9,613
Unamortized discount and debt issuance costs	(17,501)				(17,822)
	2,089,999				2,089,678
Revolving credit facility and commercial paper	150,000		150,000		150,000		150,000
Industrial development revenue bonds:
Variable-rate 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	(1,411)				(1,472)
	198,589				198,528
Less: current maturities	(25,000)				—
Long-term debt, less current maturities - Southwest Gas Corporation	$	2,413,588			$	2,438,206
Centuri:
Centuri term loan facility	$	222,668	$	225,269	$	226,648	$	230,824
Unamortized debt issuance costs	(750)				(820)
	221,918				225,828
Centuri secured revolving credit facility	26,163		26,180		26,626		26,645
Centuri other debt obligations	77,235		78,378		81,973		84,246
Less: current maturities	(42,334)				(40,433)
Long-term debt, less current maturities - Centuri	$	282,982			$	293,994
Consolidated Southwest Gas Holdings, Inc.:
Southwest Gas Corporation long-term debt	$	2,438,588			$	2,438,206
Centuri long-term debt	325,316				334,427
Less: current maturities	(67,334)				(40,433)
Long-term debt, less current maturities - Southwest Gas Holdings, Inc.	$	2,696,570			$	2,732,200

The fair values of Southwest's revolving credit facility and IDRBs are categorized as Level 1 based on the FASB’s fair value hierarchy, due to Southwest’s ability to access similar debt arrangements at measurement dates with comparable terms, including variable/market rates. The fair values of Southwest’s debentures (which include senior and medium-term 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. Centuri's secured revolving credit and term loan facility and other debt obligations (not actively traded) are categorized as Level 3; fair values were based on a conventional discounted cash flow methodology utilizing current market pricing yield curves.

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 LIBOR or an “alternate base rate,” plus in each case an applicable margin that is determined based on Southwest’s senior unsecured debt rating. At March 31, 2021, the applicable margin is 1% for loans bearing interest with reference to LIBOR and 0% for loans bearing interest with reference to the alternative base rate. At March 31, 2021, $150 million was outstanding on the long-term portion (including $50 million under the commercial paper program, discussed below) of the facility and $17 million of borrowings were outstanding on the short-term portion of this credit facility discussed below.

Southwest has a $50 million commercial paper program. Issuances under the commercial paper program are supported by Southwest’s revolving credit facility and, therefore, do not represent additional borrowing capacity under the credit facility. Borrowings under the commercial paper program are designated as long-term debt. Interest rates for the program are calculated at the then current commercial paper rate. At March 31, 2021, as noted above, $50 million of borrowings were outstanding under the commercial paper program.

Centuri has a $590 million senior secured revolving credit and term loan facility, scheduled to expire in November 2023. The capacity of the line of credit portion of the facility is $325 million; related amounts borrowed and repaid are available to be re-borrowed. The term loan portion of the facility has a limit of approximately $265 million. The $590 million facility is secured by substantially all of Centuri’s assets except those explicitly excluded under the terms of the agreement (including owned real estate and certain certificated vehicles). Centuri’s assets securing the facility at March 31, 2021 totaled $1.3 billion. At March 31, 2021, $249 million in borrowings were outstanding under Centuri’s combined secured revolving credit and term loan facility.

Short-Term Debt

Southwest Gas Holdings, Inc. has a $100 million credit facility that is scheduled to expire in April 2025 and is primarily used for short-term financing needs. There was $43 million outstanding under this credit facility as of March 31, 2021.

Under Southwest’s $400 million credit facility, Southwest had $17 million in short-term borrowings outstanding at March 31, 2021.

In March 2021, Southwest issued a $250 million Term Loan that matures March 22, 2022. The proceeds were 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. (see Deferred Purchased Gas Costs in Note 1 – Background, Organization, and Summary of Significant Accounting Policies). Interest rates for the term loan are calculated at either LIBOR 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 LIBOR and 0.000% for loans bearing interest with reference to an alternate base rate. The effective interest rate was 0.77% at March 31, 2021. The 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

LIBOR is scheduled to be discontinued as a benchmark or reference rate after 2021. In order to mitigate the impact of a discontinuance on the Company’s and Southwest’s financial condition and results of operations, management will monitor developments and work with lenders to determine the appropriate replacement/alternative reference rate for variable rate debt. At this time the Company and Southwest can provide no assurances as to the impact a LIBOR discontinuance will have on their financial condition or results of operations. Any alternative rate may be less predictable or less attractive than LIBOR.

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Other Comprehensive Income and Accumulated Other Comprehensive Income

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

Other Comprehensive Income and Accumulated Other Comprehensive Income

Note 6 – Other Comprehensive Income and Accumulated Other Comprehensive Income

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

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

	Three Months Ended March 31, 2021						Three Months Ended March 31, 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
Defined benefit pension plans:
Amortization of prior service cost	$	240	$	(58)	$	182	$	289	$	(69)	$	220
Amortization of net actuarial (gain)/loss	11,149		(2,675)		8,474		9,458		(2,270)		7,188
Regulatory adjustment	(9,575)		2,298		(7,277)		(8,395)		2,015		(6,380)
Pension plans other comprehensive income (loss)	1,814		(435)		1,379		1,352		(324)		1,028
FSIRS (designated hedging activities):
Amounts reclassified into net income	544		(131)		413		837		(201)		636
FSIRS other comprehensive income (loss)	544		(131)		413		837		(201)		636
Total other comprehensive income (loss) - Southwest Gas Corporation	2,358		(566)		1,792		2,189		(525)		1,664
Foreign currency translation adjustments:
Translation adjustments	823		—		823		(4,005)		—		(4,005)
Foreign currency other comprehensive income (loss)	823		—		823		(4,005)		—		(4,005)
Total other comprehensive income (loss) - Southwest Gas Holdings, Inc.	$	3,181	$	(566)	$	2,615	$	(1,816)	$	(525)	$	(2,341)

	Twelve Months Ended March 31, 2021						Twelve Months Ended March 31, 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
Defined benefit pension plans:
Net actuarial gain/(loss)	$	(57,539)	$	13,809	$	(43,730)	$	(71,087)	$	17,061	$	(54,026)
Amortization of prior service cost	1,106		(266)		840		1,243		(298)		945
Amortization of net actuarial (gain)/loss	39,521		(9,484)		30,037		26,990		(6,477)		20,513
Prior service cost	—		—		—		(1,878)		452		(1,426)
Regulatory adjustment	6,255		(1,502)		4,753		33,896		(8,136)		25,760
Pension plans other comprehensive income (loss)	(10,657)		2,557		(8,100)		(10,836)		2,602		(8,234)
FSIRS (designated hedging activities):
Amounts reclassified into net income	2,954		(710)		2,244		3,345		(803)		2,542
FSIRS other comprehensive income (loss)	2,954		(710)		2,244		3,345		(803)		2,542
Total other comprehensive income (loss) - Southwest Gas Corporation	(7,703)		1,847		(5,856)		(7,491)		1,799		(5,692)
Foreign currency translation adjustments:
Translation adjustments	6,541		—		6,541		(2,758)		—		(2,758)
Foreign currency other comprehensive income (loss)	6,541		—		6,541		(2,758)		—		(2,758)
Total other comprehensive income (loss) - Southwest Gas Holdings, Inc.	$	(1,162)	$	1,847	$	685	$	(10,249)	$	1,799	$	(8,450)

(1)Tax amounts are calculated using a 24% rate. The Company has elected to indefinitely reinvest the earnings of Centuri’s Canadian subsidiaries in Canada, thus precluding 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 reported in Other comprehensive income (loss).

Approximately $1.7 million of realized losses (net of tax) related to the remaining balance of Southwest’s previously settled forward-starting interest rate swap (“FSIRS”), included in AOCI at March 31, 2021, will be reclassified into interest expense within the next 12 months as the related interest payments on long-term debt occur.

The following table represents a rollforward of AOCI, presented on the Company’s Condensed Consolidated Balance Sheets and its Condensed 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, 2020	$	(77,720)	$	18,653	$	(59,067)	$	(2,719)	$	651	$	(2,068)	$	132	$	—	$	132	$	(61,003)
Translation adjustments	—		—		—		—		—		—		823		—		823		823
Other comprehensive income (loss) before reclassifications	—		—		—		—		—		—		823		—		823		823
FSIRS amount reclassified from AOCI (1)	—		—		—		544		(131)		413		—		—		—		413
Amortization of prior service cost (2)	240		(58)		182		—		—		—		—		—		—		182
Amortization of net actuarial loss (2)	11,149		(2,675)		8,474		—		—		—		—		—		—		8,474
Regulatory adjustment (3)	(9,575)		2,298		(7,277)		—		—		—		—		—		—		(7,277)
Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	1,814		(435)		1,379		544		(131)		413		823		—		823		2,615
Ending Balance AOCI March 31, 2021	$	(75,906)	$	18,218	$	(57,688)	$	(2,175)	$	520	$	(1,655)	$	955	$	—	$	955	$	(58,388)

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

(2)These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost 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 Condensed Consolidated Balance Sheets).

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

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

	Defined Benefit Plans						FSIRS
(Thousands of dollars)	Before-Tax		Tax (Expense) Benefit (8)		After-Tax		Before-Tax		Tax (Expense) Benefit (8)		After-Tax		AOCI
Beginning Balance AOCI December 31, 2020	$	(77,720)	$	18,653	$	(59,067)	$	(2,719)	$	651	$	(2,068)	$	(61,135)
FSIRS amount reclassified from AOCI (5)	—		—		—		544		(131)		413		413
Amortization of prior service cost (6)	240		(58)		182		—		—		—		182
Amortization of net actuarial loss (6)	11,149		(2,675)		8,474		—		—		—		8,474
Regulatory adjustment (7)	(9,575)		2,298		(7,277)		—		—		—		(7,277)
Net current period other comprehensive income attributable to Southwest Gas Corporation	1,814		(435)		1,379		544		(131)		413		1,792
Ending Balance AOCI March 31, 2021	$	(75,906)	$	18,218	$	(57,688)	$	(2,175)	$	520	$	(1,655)	$	(59,343)

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

(6)These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details).

(7)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 Southwest’s Condensed Consolidated Balance Sheets).

(8)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:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Net actuarial loss	$	(491,634)	$	(502,783)
Prior service cost	(2,247)		(2,487)
Less: amount recognized in regulatory assets	417,975		427,550
Recognized in AOCI	$	(75,906)	$	(77,720)

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Segment Information

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Segment Information

Note 7 – Segment Information

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:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Centuri accounts receivable for services provided to Southwest	$	11,344	$	13,956

The Company has two reportable segments: natural gas operations and utility infrastructure services. Southwest has a single reportable segment that is referred to herein as the natural gas operations segment of the Company. In order to reconcile to net income as disclosed in the Condensed 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 the natural gas operations and utility infrastructure services segments is as follows:

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Other		Total
Three Months Ended March 31, 2021
Revenues from external customers	$	521,932	$	339,772	$	—	$	861,704
Intersegment revenues	—		24,203		—		24,203
Total	$	521,932	$	363,975	$	—	$	885,907
Segment net income (loss)	$	118,715	$	(859)	$	(563)	$	117,293
Three Months Ended March 31, 2020
Revenues from external customers	$	502,827	$	300,291	$	—	$	803,118
Intersegment revenues	—		33,202		—		33,202
Total	$	502,827	$	333,493	$	—	$	836,320
Segment net income (loss)	$	83,599	$	(10,204)	$	(853)	$	72,542

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Other		Total
Twelve Months Ended March 31, 2021
Revenues from external customers	$	1,369,690	$	1,852,910	$	—	$	3,222,600
Intersegment revenues	—		125,860		—		125,860
Total	$	1,369,690	$	1,978,770	$	—	$	3,348,460
Segment net income (loss)	$	194,234	$	84,207	$	(1,366)	$	277,075
Twelve Months Ended March 31, 2020
Revenues from external customers	$	1,351,089	$	1,618,354	$	—	$	2,969,443
Intersegment revenues	—		153,255		—		153,255
Total	$	1,351,089	$	1,771,609	$	—	$	3,122,698
Segment net income (loss)	$	143,381	$	50,231	$	(1,943)	$	191,669

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

3 Months Ended

Mar. 31, 2021

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Nature of Operations

Nature of Operations. Southwest Gas Holdings, Inc. is a holding company, owning all of the shares of common stock of Southwest Gas Corporation (“Southwest” or the “natural gas operations” segment) and all of the shares of common stock of Centuri Group, Inc. (“Centuri,” or the “utility infrastructure services” 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 operations segment are higher during winter periods due to the seasonality incorporated in its regulatory rate structures.

Centuri is a comprehensive utility infrastructure services enterprise dedicated to delivering a diverse array of solutions to North America’s gas and electric providers. Centuri derives revenue primarily from installation, replacement, repair, and maintenance of energy distribution systems. Centuri operations are generally conducted under the business names of NPL Construction Co. (“NPL”), NPL Canada Ltd. (“NPL Canada”), New England Utility Constructors, Inc. (“Neuco”), and Linetec Services, LLC (“Linetec”). Utility infrastructure services activity is seasonal in most of Centuri’s operating areas. Peak periods are the summer and fall months in colder climate areas, such as the northeastern and midwestern United States (“U.S.”) and in Canada. In warmer climate areas, such as the southwestern and southeastern U.S., utility infrastructure services activity continues year round.

Basis of Presentation

Basis of Presentation. The condensed consolidated financial statements of Southwest Gas Holdings, Inc. and subsidiaries (the “Company”) and Southwest included herein have been prepared pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). Certain information and footnote disclosures normally included in financial statements prepared in accordance with U.S. generally accepted accounting principles (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations. No substantive change has occurred with regard to the Company’s business segments on the whole.

The preparation of the condensed consolidated financial statements 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. In the opinion of management, all adjustments, consisting of normal recurring items and estimates necessary for a fair depiction of results for the interim periods, have been made. In association with the novel Coronavirus (“COVID-19”) pandemic environment, utility operations, and to a large extent, utility infrastructure services, have been deemed “essential services.” Management has considered the impact of the pandemic and adjusted certain estimates, where relevant, used in the preparation of the condensed consolidated financial statements.

These condensed consolidated financial statements should be read in conjunction with the consolidated financial statements and notes thereto included in the 2020 Annual Report to Stockholders, which is incorporated by reference into the 2020 Form 10-K.

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 in valuing cash and cash equivalents, long-term debt outstanding, and assets of the qualified pension plan and postretirement benefit plans required to be recorded and/or disclosed at fair value.

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 Southwest and the Company include money market fund investments totaling approximately $40,000 for each entity at March 31, 2021 and December 31, 2020, respectively, which fall within Level 2 of the fair value hierarchy, due to the asset valuation methods used by money market funds.

Typical non-cash investing activities include customer advances applied as contributions toward utility construction activity, and capital expenditures that were not paid as of period-end reporting dates, but rather included in accounts payable. Typical activities that represent aspects of both non-cash investing and non-cash financing activities relate to right-of-use assets obtained in exchange for lease liabilities (including, at times, lease terminations and modifications). Amounts related to these collective activities were immaterial for the periods presented herein.

Intercompany Transactions

Intercompany Transactions. Centuri recognizes revenues generated from contracts with Southwest (see Note 7 – Segment Information). The accounts receivable balance, revenues, and associated profits are included in the condensed consolidated financial statements of the Company and Southwest and were not eliminated during consolidation in accordance with accounting treatment for rate-regulated entities.

Accounts Receivable, net of allowances

Accounts Receivable, net of 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 no billing due dates customarily extending beyond one month, with customers’ credit worthiness assessed upon account creation by evaluation of other utility service and related payment history. Due to the ongoing COVID-19 pandemic, Southwest continued the moratorium initiated in March 2020 on disconnection of natural gas service for non-payment, but recommenced assessing late fees in Nevada and Arizona in April 2021, with late fees in California expected to recommence in the latter half of 2021. Southwest is actively working with customers experiencing financial hardship by means of flexible payment options. Management continues to monitor expected credit losses in light of the evolving impact of COVID-19. The allowance as of March 31, 2021 reflects the expected impact from the pandemic on balances as of that date, including consideration of customers’ ability to pay currently and once the moratorium on disconnections is lifted.

Utility infrastructure services contracts 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 has not been significantly impacted, nor does it anticipate it will experience significant difficulty in collecting amounts due, as a result of the current environment surrounding COVID-19 given the nature of its customers.

Activity between periods in the allowance for uncollectibles and the balances as of the periods presented within the Company’s and Southwest’s financial statements were not material to the condensed consolidated financial statements overall.

Deferred Purchased Gas Costs

Deferred Purchased Gas Costs. The various regulatory commissions have established procedures to enable Southwest to adjust its 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.

In mid-February 2021, the central U.S. (from south Texas to North Dakota and the eastern Rocky Mountains) experienced extreme cold temperatures, which increased natural gas demand and caused supply issues due to wellhead freeze-offs, power outages, or other adverse operating conditions upstream of Southwest’s distribution systems. These conditions caused daily natural gas prices to reach unprecedented levels. During this time, Southwest secured natural gas supplies, albeit at substantially higher prices, maintaining service to its customers. The incremental cost for these supplies was approximately $250 million, funded using a 364-day $250 million Bank Term Loan executed in March 2021 (see Note 5 – Debt). The incremental gas costs are expected to be collected from customers through the purchased gas adjustment (“PGA”) mechanisms.

Following the extreme weather event, an interstate transmission pipeline company billed Southwest, in addition to customary transmission costs, $65 million for pipeline imbalance charges, allegedly incurred during the period of the pipeline’s critical operation condition. However, Southwest has formally disputed these imbalance charges and believes that no amounts are due to the pipeline. Consequently, Southwest has not recognized this charge. Pipeline transmission costs, including periodic imbalance charges, are components of the cost of gas recovered from customers through the PGA and similar mechanisms.

Prepaid and other current assets

Prepaid and other current assets. Prepaid and other current assets includes gas pipe materials and operating supplies of $47 million at March 31, 2021 and $50 million at December 31, 2020 (carried at weighted average cost).

Goodwill

Goodwill. Goodwill is assessed as of October 1st each year for impairment, or more frequently, if circumstances indicate an impairment to the carrying value of goodwill may have occurred. Management of the Company and Southwest considered its reporting units and segments and determined that its segments and reporting units remain consistent between periods presented below, and that no change was necessary with regard to the level at which goodwill is assessed for impairment.

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 amounts payable under regulatory mechanisms, customary accrued expenses for employee compensation and benefits, declared but unpaid dividends, and miscellaneous other accrued liabilities. Other current liabilities for the Company includes $34.5 million and $32.6 million of dividends declared, as well as $37 million and $25.2 million of accrued property taxes, as of March 31, 2021 and December 31, 2020, respectively.

Earnings Per Share

Earnings Per Share. Basic earnings per share (“EPS”) in each period of this report were calculated by dividing net income 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). Unless otherwise noted, the term “Earnings Per Share” refers to Basic EPS.

Recent Accounting Standards Updates

Recent Accounting Standards Updates.

Accounting pronouncements adopted in 2021:

In December 2019, the Financial Accounting Standards Board (the “FASB”) issued ASU 2019-12 “Income Taxes (Topic 740): Simplifying the Accounting for Income Taxes.” The update simplifies the accounting for income taxes by removing certain exceptions to the general principles, as well as improving consistent application in Topic 740 by clarifying and amending existing guidance. The Company and Southwest adopted the update in the first quarter of 2021, the impact of which was not material to the condensed consolidated financial statements of the Company or Southwest.

Recently issued accounting pronouncements that will be effective after 2021:

In March 2020, the FASB issued 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 Topic 848) to replace a reference rate affected by such reform. The update applies only to contracts and hedging relationships that reference the London Interbank Offered Rate (“LIBOR”) or another 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. Management will 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 5 – 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 update is effective for fiscal years beginning after December 15, 2021, including interim periods within those fiscal years; early adoption is permitted. Management is evaluating what impacts, if any, this update might have on the Company’s consolidated financial statements and disclosures.

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

3 Months Ended

Mar. 31, 2021

Organization, Consolidation and Presentation of Financial Statements [Abstract]

Schedule of Other Property and Investments

Other Property and Investments. Other property and investments on the Condensed Consolidated Balance Sheets includes:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Southwest Gas Corporation:
Net cash surrender value of COLI policies	$	143,618	$	140,874
Other property	2,720		2,737
Total Southwest Gas Corporation	146,338		143,611
Centuri property, equipment, and intangibles	1,106,855		1,089,414
Centuri accumulated provision for depreciation and amortization	(439,126)		(422,741)
Other property and investments	28,605		23,961
Total Southwest Gas Holdings, Inc.	$	842,672	$	834,245

Schedule of Goodwill

Goodwill on Southwest’s and the Company’s Condensed Consolidated Balance Sheets includes:

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Total Company
December 31, 2020	$	10,095	$	335,089	$	345,184
Foreign currency translation adjustment	—		1,369		1,369
March 31, 2021	$	10,095	$	336,458	$	346,553

Schedule of Significant Items Included in Other Income (Deductions)

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

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Southwest Gas Corporation - natural gas operations segment:
Change in COLI policies	$	2,700	$	(15,500)	$	27,400	$	(5,700)
Interest income	716		1,388		3,343		6,147
Equity AFUDC	981		1,061		4,644		4,262
Other components of net periodic benefit cost	(3,505)		(5,005)		(18,522)		(16,299)
Miscellaneous income and (expense)	(342)		(2,480)		(2,369)		(5,375)
Southwest Gas Corporation - total other income (deductions)	550		(20,536)		14,496		(16,965)
Utility infrastructure services segment:
Foreign transaction gain (loss)	(3)		(10)		(9)		5
Miscellaneous income and (expense)	(99)		(232)		(58)		(656)
Centuri - total other income (deductions)	(102)		(242)		(67)		(651)
Corporate and administrative	—		8		—		92
Consolidated Southwest Gas Holdings, Inc. - total other income (deductions)	$	448	$	(20,770)	$	14,429	$	(17,524)

Summary of Redeemable Noncontrolling Interest

The following depicts the change to the balance of the redeemable noncontrolling interest:

(Thousands of dollars):	Redeemable Noncontrolling Interest
Balance, December 31, 2020	$	165,716
Net income attributable to redeemable noncontrolling interest	1,552
Redemption value adjustment	38,018
Balance, March 31, 2021	$	205,286

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:

	Three Months Ended March 31,		Twelve Months Ended March 31,
(In thousands)	2021	2020	2021	2020
Weighted average basic shares	57,600	55,310	56,564	54,726
Effect of dilutive securities:
Management Incentive Plan shares	—	—	—	9
Restricted stock units (1)	79	53	85	57
Weighted average diluted shares	57,679	55,363	56,649	54,792

(1) The number of securities included 75,000 and 50,000 performance shares during the three months ending March 31, 2021 and 2020, and 76,000 and 48,000 performance shares during the twelve months ending March 31, 2021 and 2020, respectively, the total of which was derived by assuming that target performance will be achieved during the relevant performance period.

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Components of Net Periodic Benefit Cost (Tables)

3 Months Ended

Mar. 31, 2021

Retirement Benefits [Abstract]

Schedule of Net Periodic Benefit Costs

The service cost component of net periodic benefit costs included in the table below is a component of an overhead loading process associated with the cost of labor. The overhead process ultimately results in allocation of service cost 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 utility plant, and deferred charges and other assets for both the Company and Southwest. The other components of net periodic benefit cost are reflected in Other income (deductions) on the Condensed Consolidated Statements of Income of each entity.

	Qualified Retirement Plan
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	10,290	$	8,574	$	36,015	$	27,972
Interest cost	10,108		11,388		44,275		48,142
Expected return on plan assets	(18,088)		(16,324)		(67,060)		(61,507)
Amortization of net actuarial loss	10,489		9,007		37,507		25,774
Net periodic benefit cost	$	12,799	$	12,645	$	50,737	$	40,381
	SERP
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	131	$	98	$	422	$	298
Interest cost	358		401		1,561		1,721
Amortization of net actuarial loss	660		451		2,014		1,216
Net periodic benefit cost	$	1,149	$	950	$	3,997	$	3,235
	PBOP
	March 31,
	Three Months				Twelve Months
	2021		2020		2021		2020
(Thousands of dollars)
Service cost	$	423	$	396	$	1,608	$	1,353
Interest cost	548		645		2,485		2,929
Expected return on plan assets	(810)		(852)		(3,366)		(3,219)
Amortization of prior service costs	240		289		1,106		1,243
Net periodic benefit cost	$	401	$	478	$	1,833	$	2,306

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Revenue (Tables)

3 Months Ended

Mar. 31, 2021

Revenue from Contract with Customer [Abstract]

Summary of Revenue Disaggregated by Service Type and Contract Type

Gas operating revenues on the Condensed Consolidated Statements of Income of both the Company and Southwest include revenue from contracts with customers, which is shown below, disaggregated by customer type, and various categories of revenue:

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Residential	$	403,143	$	378,555	$	983,108	$	934,115
Small commercial	81,398		82,463		220,476		241,970
Large commercial	12,673		12,667		44,639		47,640
Industrial/other	13,770		6,702		33,310		22,298
Transportation	24,536		24,406		88,345		91,884
Revenue from contracts with customers	535,520		504,793		1,369,878		1,337,907
Alternative revenue program revenues (deferrals)	(16,373)		(3,765)		(468)		5,668
Other revenues (1)	2,785		1,799		280		7,514
Total Gas operating revenues	$	521,932	$	502,827	$	1,369,690	$	1,351,089

(1) 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 customer rates expected to be returned to customers in future periods. Late fees and certain other fees were reduced, for the three- and twelve-month periods ended March 31, 2021, due to a moratorium on late fees and disconnection for nonpayment during the COVID-19 pandemic.

The following tables display Centuri’s revenue, reflected as Utility infrastructure services revenues on the Condensed Consolidated Statements of Income of the Company, representing revenue from contracts with customers disaggregated by service and contract types:

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Service Types:
Gas infrastructure services	$	221,837	$	217,709	$	1,265,288	$	1,258,790
Electric power infrastructure services	93,961		72,320		433,467		267,736
Other	48,177		43,464		280,015		245,083
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609

	Three Months Ended March 31,				Twelve Months Ended March 31,
(Thousands of dollars)	2021		2020		2021		2020
Contract Types:
Master services agreement	$	293,680	$	263,545	$	1,520,144	$	1,411,267
Bid contract	70,295		69,948		458,626		360,342
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609
Unit price contracts	$	234,449	$	243,136	$	1,347,953	$	1,387,706
Fixed price contracts	34,594		27,545		164,750		101,931
Time and materials contracts	94,932		62,812		466,067		281,972
Total Utility infrastructure services revenues	$	363,975	$	333,493	$	1,978,770	$	1,771,609

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

The following table provides information about contracts receivable and revenue earned on contracts in progress in excess of billings (contract asset), which are both included within Accounts receivable, net of allowances, as well as amounts billed in excess of revenue earned on contracts (contract liability), which are included in Other current liabilities as of March 31, 2021 and December 31, 2020 on the Company’s Condensed Consolidated Balance Sheets:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Contracts receivable, net	$	197,357	$	278,316
Revenue earned on contracts in progress in excess of billings	107,336		96,996
Amounts billed in excess of revenue earned on contracts	5,985		4,507

Schedule of Utility Infrastructure Services Contracts Receivable

Utility infrastructure services contracts receivable consists of the following:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Billed on completed contracts and contracts in progress	$	193,042	$	273,778
Other receivables	5,789		6,692
Contracts receivable, gross	198,831		280,470
Allowance for doubtful accounts	(1,474)		(2,154)
Contracts receivable, net	$	197,357	$	278,316

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Common Stock (Tables)

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

Schedule of Common Stock Activity

The following table provides the activity under the Equity Shelf Program for the three-month and life-to-date periods ended March 31, 2021:

	Three Months Ended		Life-To-Date Ended
	March 31, 2021
Gross proceeds	$	46,448,484	$	299,999,974
Less: agent commissions	(464,485)		(3,000,000)
Net proceeds	$	45,983,999	$	296,999,974
Number of shares sold	705,957		4,102,414
Weighted average price per share	$	65.80	$	73.13

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Debt (Tables)

3 Months Ended

Mar. 31, 2021

Debt Disclosure [Abstract]

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

	March 31, 2021				December 31, 2020
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
(Thousands of dollars)
Southwest Gas Corporation:
Debentures:
Notes, 6.1%, due 2041	$	125,000	$	160,651	$	125,000	$	174,858
Notes, 3.875%, due 2022	250,000		256,693		250,000		258,825
Notes, 4.875%, due 2043	250,000		288,500		250,000		317,190
Notes, 3.8%, due 2046	300,000		306,261		300,000		347,046
Notes, 3.7%, due 2028	300,000		324,069		300,000		344,553
Notes, 4.15%, due 2049	300,000		324,183		300,000		370,278
Notes, 2.2%, due 2030	450,000		438,912		450,000		474,552
8% Series, due 2026	75,000		95,894		75,000		99,723
Medium-term notes, 7.78% series, due 2022	25,000		26,201		25,000		26,663
Medium-term notes, 7.92% series, due 2027	25,000		32,138		25,000		33,802
Medium-term notes, 6.76% series, due 2027	7,500		9,127		7,500		9,613
Unamortized discount and debt issuance costs	(17,501)				(17,822)
	2,089,999				2,089,678
Revolving credit facility and commercial paper	150,000		150,000		150,000		150,000
Industrial development revenue bonds:
Variable-rate 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	(1,411)				(1,472)
	198,589				198,528
Less: current maturities	(25,000)				—
Long-term debt, less current maturities - Southwest Gas Corporation	$	2,413,588			$	2,438,206
Centuri:
Centuri term loan facility	$	222,668	$	225,269	$	226,648	$	230,824
Unamortized debt issuance costs	(750)				(820)
	221,918				225,828
Centuri secured revolving credit facility	26,163		26,180		26,626		26,645
Centuri other debt obligations	77,235		78,378		81,973		84,246
Less: current maturities	(42,334)				(40,433)
Long-term debt, less current maturities - Centuri	$	282,982			$	293,994
Consolidated Southwest Gas Holdings, Inc.:
Southwest Gas Corporation long-term debt	$	2,438,588			$	2,438,206
Centuri long-term debt	325,316				334,427
Less: current maturities	(67,334)				(40,433)
Long-term debt, less current maturities - Southwest Gas Holdings, Inc.	$	2,696,570			$	2,732,200

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Other Comprehensive Income and Accumulated Other Comprehensive Income (Tables)

3 Months Ended

Mar. 31, 2021

Equity [Abstract]

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

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

	Three Months Ended March 31, 2021						Three Months Ended March 31, 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
Defined benefit pension plans:
Amortization of prior service cost	$	240	$	(58)	$	182	$	289	$	(69)	$	220
Amortization of net actuarial (gain)/loss	11,149		(2,675)		8,474		9,458		(2,270)		7,188
Regulatory adjustment	(9,575)		2,298		(7,277)		(8,395)		2,015		(6,380)
Pension plans other comprehensive income (loss)	1,814		(435)		1,379		1,352		(324)		1,028
FSIRS (designated hedging activities):
Amounts reclassified into net income	544		(131)		413		837		(201)		636
FSIRS other comprehensive income (loss)	544		(131)		413		837		(201)		636
Total other comprehensive income (loss) - Southwest Gas Corporation	2,358		(566)		1,792		2,189		(525)		1,664
Foreign currency translation adjustments:
Translation adjustments	823		—		823		(4,005)		—		(4,005)
Foreign currency other comprehensive income (loss)	823		—		823		(4,005)		—		(4,005)
Total other comprehensive income (loss) - Southwest Gas Holdings, Inc.	$	3,181	$	(566)	$	2,615	$	(1,816)	$	(525)	$	(2,341)

	Twelve Months Ended March 31, 2021						Twelve Months Ended March 31, 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
Defined benefit pension plans:
Net actuarial gain/(loss)	$	(57,539)	$	13,809	$	(43,730)	$	(71,087)	$	17,061	$	(54,026)
Amortization of prior service cost	1,106		(266)		840		1,243		(298)		945
Amortization of net actuarial (gain)/loss	39,521		(9,484)		30,037		26,990		(6,477)		20,513
Prior service cost	—		—		—		(1,878)		452		(1,426)
Regulatory adjustment	6,255		(1,502)		4,753		33,896		(8,136)		25,760
Pension plans other comprehensive income (loss)	(10,657)		2,557		(8,100)		(10,836)		2,602		(8,234)
FSIRS (designated hedging activities):
Amounts reclassified into net income	2,954		(710)		2,244		3,345		(803)		2,542
FSIRS other comprehensive income (loss)	2,954		(710)		2,244		3,345		(803)		2,542
Total other comprehensive income (loss) - Southwest Gas Corporation	(7,703)		1,847		(5,856)		(7,491)		1,799		(5,692)
Foreign currency translation adjustments:
Translation adjustments	6,541		—		6,541		(2,758)		—		(2,758)
Foreign currency other comprehensive income (loss)	6,541		—		6,541		(2,758)		—		(2,758)
Total other comprehensive income (loss) - Southwest Gas Holdings, Inc.	$	(1,162)	$	1,847	$	685	$	(10,249)	$	1,799	$	(8,450)

(1)Tax amounts are calculated using a 24% rate. The Company has elected to indefinitely reinvest the earnings of Centuri’s Canadian subsidiaries in Canada, thus precluding 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 reported in Other comprehensive income (loss).

Rollforward of Accumulated Other Comprehensive Income

The following table represents a rollforward of AOCI, presented on the Company’s Condensed Consolidated Balance Sheets and its Condensed 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, 2020	$	(77,720)	$	18,653	$	(59,067)	$	(2,719)	$	651	$	(2,068)	$	132	$	—	$	132	$	(61,003)
Translation adjustments	—		—		—		—		—		—		823		—		823		823
Other comprehensive income (loss) before reclassifications	—		—		—		—		—		—		823		—		823		823
FSIRS amount reclassified from AOCI (1)	—		—		—		544		(131)		413		—		—		—		413
Amortization of prior service cost (2)	240		(58)		182		—		—		—		—		—		—		182
Amortization of net actuarial loss (2)	11,149		(2,675)		8,474		—		—		—		—		—		—		8,474
Regulatory adjustment (3)	(9,575)		2,298		(7,277)		—		—		—		—		—		—		(7,277)
Net current period other comprehensive income (loss) attributable to Southwest Gas Holdings, Inc.	1,814		(435)		1,379		544		(131)		413		823		—		823		2,615
Ending Balance AOCI March 31, 2021	$	(75,906)	$	18,218	$	(57,688)	$	(2,175)	$	520	$	(1,655)	$	955	$	—	$	955	$	(58,388)

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

(2)These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost 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 Condensed Consolidated Balance Sheets).

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

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

	Defined Benefit Plans						FSIRS
(Thousands of dollars)	Before-Tax		Tax (Expense) Benefit (8)		After-Tax		Before-Tax		Tax (Expense) Benefit (8)		After-Tax		AOCI
Beginning Balance AOCI December 31, 2020	$	(77,720)	$	18,653	$	(59,067)	$	(2,719)	$	651	$	(2,068)	$	(61,135)
FSIRS amount reclassified from AOCI (5)	—		—		—		544		(131)		413		413
Amortization of prior service cost (6)	240		(58)		182		—		—		—		182
Amortization of net actuarial loss (6)	11,149		(2,675)		8,474		—		—		—		8,474
Regulatory adjustment (7)	(9,575)		2,298		(7,277)		—		—		—		(7,277)
Net current period other comprehensive income attributable to Southwest Gas Corporation	1,814		(435)		1,379		544		(131)		413		1,792
Ending Balance AOCI March 31, 2021	$	(75,906)	$	18,218	$	(57,688)	$	(2,175)	$	520	$	(1,655)	$	(59,343)

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

(6)These AOCI components are included in the computation of net periodic benefit cost (see Note 2 – Components of Net Periodic Benefit Cost for additional details).

(7)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 Southwest’s Condensed Consolidated Balance Sheets).

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

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:

(Thousands of dollars)	March 31, 2021		December 31, 2020
Net actuarial loss	$	(491,634)	$	(502,783)
Prior service cost	(2,247)		(2,487)
Less: amount recognized in regulatory assets	417,975		427,550
Recognized in AOCI	$	(75,906)	$	(77,720)

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Segment Information (Tables)

3 Months Ended

Mar. 31, 2021

Segment Reporting [Abstract]

Accounts Receivable for Services

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

(Thousands of dollars)	March 31, 2021		December 31, 2020
Centuri accounts receivable for services provided to Southwest	$	11,344	$	13,956

Schedule of Segment Reporting Information

The financial information pertaining to the natural gas operations and utility infrastructure services segments is as follows:

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Other		Total
Three Months Ended March 31, 2021
Revenues from external customers	$	521,932	$	339,772	$	—	$	861,704
Intersegment revenues	—		24,203		—		24,203
Total	$	521,932	$	363,975	$	—	$	885,907
Segment net income (loss)	$	118,715	$	(859)	$	(563)	$	117,293
Three Months Ended March 31, 2020
Revenues from external customers	$	502,827	$	300,291	$	—	$	803,118
Intersegment revenues	—		33,202		—		33,202
Total	$	502,827	$	333,493	$	—	$	836,320
Segment net income (loss)	$	83,599	$	(10,204)	$	(853)	$	72,542

(Thousands of dollars)	Natural Gas Operations		Utility Infrastructure Services		Other		Total
Twelve Months Ended March 31, 2021
Revenues from external customers	$	1,369,690	$	1,852,910	$	—	$	3,222,600
Intersegment revenues	—		125,860		—		125,860
Total	$	1,369,690	$	1,978,770	$	—	$	3,348,460
Segment net income (loss)	$	194,234	$	84,207	$	(1,366)	$	277,075
Twelve Months Ended March 31, 2020
Revenues from external customers	$	1,351,089	$	1,618,354	$	—	$	2,969,443
Intersegment revenues	—		153,255		—		153,255
Total	$	1,351,089	$	1,771,609	$	—	$	3,122,698
Segment net income (loss)	$	143,381	$	50,231	$	(1,943)	$	191,669

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Background, Organization, and Summary of Significant Accounting Policies - Narratives (Details)	1 Months Ended		2 Months Ended	3 Months Ended
	Mar. 31, 2021 USD ($) state	Feb. 28, 2021 USD ($)	Mar. 31, 2021 USD ($) state	Mar. 31, 2021 USD ($) state	Dec. 31, 2020 USD ($)	Nov. 30, 2018
Significant Accounting Policies [Line Items]
Number of states in which entity operates | state	3		3	3
Accounts receivable, extending period				1 month
Deferred purchased gas costs, recovered or refunded period				1 year
Deferred purchased gas costs, estimated incremental costs			$ 250,000,000
Deferred purchased gas costs, pipeline imbalance charges		$ 65,000,000
Goodwill impairment				$ 0
Dividends declared but not yet paid	$ 34,500,000		34,500,000	34,500,000	$ 32,600,000
Accrued property taxes	37,000,000		37,000,000	37,000,000	25,200,000
Redemption value adjustments				38,018,000
Linetec
Significant Accounting Policies [Line Items]
Ownership percentage by noncontrolling owners						20.00%
Gas Pipe Materials and Supplies | Prepaid and other current assets
Significant Accounting Policies [Line Items]
Gas pipe materials and operating supplies	47,000,000		47,000,000	47,000,000	50,000,000
Pooled Funds and Mutual Funds
Significant Accounting Policies [Line Items]
Money market fund investments	$ 40,000		40,000	40,000	40,000
Southwest Gas Corporation | $250 Million Term Loan
Significant Accounting Policies [Line Items]
Debt instrument, term	364 days
Debt instrument, face amount	$ 250,000,000		250,000,000	250,000,000
Southwest Gas Corporation | Pooled Funds and Mutual Funds
Significant Accounting Policies [Line Items]
Money market fund investments	$ 40,000		$ 40,000	$ 40,000	$ 40,000

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Background, Organization, and Summary of Significant Accounting Policies - Schedule of Other Property and Investments (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Property, Plant and Equipment [Line Items]
Other property and investments	$ 28,605	$ 23,961
Total	842,672	834,245
Southwest Gas Corporation
Property, Plant and Equipment [Line Items]
Net cash surrender value of COLI policies	143,618	140,874
Other property and investments	2,720	2,737
Total	146,338	143,611
Centuri
Property, Plant and Equipment [Line Items]
Centuri property, equipment, and intangibles	1,106,855	1,089,414
Centuri accumulated provision for depreciation and amortization	$ (439,126)	$ (422,741)

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Background, Organization, and Summary of Significant Accounting Policies - Schedule of Goodwill (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Goodwill [Roll Forward]
Goodwill, beginning balance	$ 345,184
Foreign currency translation adjustment	1,369
Goodwill, ending balance	346,553
Natural Gas Operations
Goodwill [Roll Forward]
Goodwill, beginning balance	10,095
Foreign currency translation adjustment	0
Goodwill, ending balance	10,095
Utility Infrastructure Services
Goodwill [Roll Forward]
Goodwill, beginning balance	335,089
Foreign currency translation adjustment	1,369
Goodwill, ending balance	$ 336,458

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Background, Organization, and Summary of Significant Accounting Policies - Other Income (Deductions) (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Other income (deductions)
Total other income (deductions)	$ 448	$ (20,770)	$ 14,429	$ (17,524)
Southwest Gas Corporation
Other income (deductions)
Total other income (deductions)	550	(20,536)	14,496	(16,965)
Revenues from external customers | Natural Gas Operations | Southwest Gas Corporation
Other income (deductions)
Change in COLI policies	2,700	(15,500)	27,400	(5,700)
Interest income	716	1,388	3,343	6,147
Equity AFUDC	981	1,061	4,644	4,262
Other components of net periodic benefit cost	(3,505)	(5,005)	(18,522)	(16,299)
Miscellaneous income and (expense)	(342)	(2,480)	(2,369)	(5,375)
Total other income (deductions)	550	(20,536)	14,496	(16,965)
Revenues from external customers | Utility Infrastructure Services Segment | Centuri
Other income (deductions)
Miscellaneous income and (expense)	(99)	(232)	(58)	(656)
Foreign transaction gain (loss)	(3)	(10)	(9)	5
Total other income (deductions)	(102)	(242)	(67)	(651)
Corporate and administrative
Other income (deductions)
Total other income (deductions)	$ 0	$ 8	$ 0	$ 92

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Background, Organization, and Summary of Significant Accounting Policies - Summary of Redeemable Noncontrolling Interest (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2021 USD ($)
Movement In Redeemable Noncontrolling Interest [Roll Forward]
Redeemable noncontrolling interest, beginning balance	$ 165,716
Net income attributable to redeemable noncontrolling interest	1,552
Redemption value adjustment	38,018
Redeemable noncontrolling interest, ending balance	$ 205,286

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Background, Organization, and Summary of Significant Accounting Policies - Schedule of Earnings Per Share (Details) - shares shares in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Weighted average basic shares (in shares)	57,600	55,310	56,564	54,726
Effect of dilutive securities:
Management Incentive Plan shares (in shares)	0	0	0	9
Restricted stock units (in shares)	79	53	85	57
Weighted average diluted shares (in shares)	57,679	55,363	56,649	54,792
Number of performance share units granted (in shares)	75	50	76	48

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Components of Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Qualified Retirement Plan
Defined Benefit Plan Disclosure [Line Items]
Service cost	$ 10,290	$ 8,574	$ 36,015	$ 27,972
Interest cost	10,108	11,388	44,275	48,142
Expected return on plan assets	(18,088)	(16,324)	(67,060)	(61,507)
Amortization of net actuarial loss	10,489	9,007	37,507	25,774
Net periodic benefit cost	12,799	12,645	50,737	40,381
SERP
Defined Benefit Plan Disclosure [Line Items]
Service cost	131	98	422	298
Interest cost	358	401	1,561	1,721
Amortization of net actuarial loss	660	451	2,014	1,216
Net periodic benefit cost	1,149	950	3,997	3,235
PBOP
Defined Benefit Plan Disclosure [Line Items]
Service cost	423	396	1,608	1,353
Interest cost	548	645	2,485	2,929
Expected return on plan assets	(810)	(852)	(3,366)	(3,219)
Amortization of prior service costs	240	289	1,106	1,243
Net periodic benefit cost	$ 401	$ 478	$ 1,833	$ 2,306

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Revenue - Schedule of Gas Operating Revenue (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 535,520	$ 504,793	$ 1,369,878	$ 1,337,907
Alternative revenue program revenues (deferrals)	(16,373)	(3,765)	(468)	5,668
Other revenues (1)	2,785	1,799	280	7,514
Total Gas operating revenues	521,932	502,827	1,369,690	1,351,089
Residential
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	403,143	378,555	983,108	934,115
Small commercial
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	81,398	82,463	220,476	241,970
Large commercial
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	12,673	12,667	44,639	47,640
Industrial/other
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	13,770	6,702	33,310	22,298
Transportation
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 24,536	$ 24,406	$ 88,345	$ 91,884

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Revenue - Summary of Revenue Disaggregated by Service Type, and Contract Type (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 535,520	$ 504,793	$ 1,369,878	$ 1,337,907
Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	363,975	333,493	1,978,770	1,771,609
Master services agreement | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	293,680	263,545	1,520,144	1,411,267
Bid contract | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	70,295	69,948	458,626	360,342
Unit price contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	234,449	243,136	1,347,953	1,387,706
Fixed price contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	34,594	27,545	164,750	101,931
Time and materials contracts | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	94,932	62,812	466,067	281,972
Gas infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	221,837	217,709	1,265,288	1,258,790
Electric power infrastructure services | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	93,961	72,320	433,467	267,736
Other | Centuri
Disaggregation of Revenue [Line Items]
Revenue from contracts with customers	$ 48,177	$ 43,464	$ 280,015	$ 245,083

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Revenue - Summary of Information about Receivables (Details) - USD ($) $ in Thousands	3 Months Ended	12 Months Ended
	Mar. 31, 2021	Dec. 31, 2020
Revenue from Contract with Customer [Abstract]
Contracts receivable, net	$ 197,357	$ 278,316
Revenue earned on contracts in progress in excess of billings	107,336	96,996
Amounts billed in excess of revenue earned on contracts	$ 5,985	$ 4,507

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Revenue - Narratives (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($) Contract
Segment Reporting Information [Line Items]
Change in contract liability, revenue recognized | $	$ 4.5
Centuri
Segment Reporting Information [Line Items]
Number of contracts with original duration more than one year | Contract	18

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Revenue - Revenue Performance Obligation (Details) - Centuri - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2021-04-01 $ in Millions	Mar. 31, 2021 USD ($)
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Transaction price allocated to unsatisfied performance obligations of contracts	$ 48.7
Transaction price allocated to unsatisfied performance obligations of contracts, period	2 years

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Revenue - Schedule of Utility Infrastructure Services Contracts Receivable (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	$ 198,831	$ 280,470
Allowance for doubtful accounts	(1,474)	(2,154)
Contracts receivable, net	197,357	278,316
Billed On Completed Contracts And Contracts In Progress
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	193,042	273,778
Other Receivables
Disaggregation of Revenue [Line Items]
Contracts receivable, gross	$ 5,789	$ 6,692

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Common Stock (Details) - USD ($)	3 Months Ended		12 Months Ended		23 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Apr. 08, 2021	May 08, 2019
Class of Stock [Line Items]
Net proceeds	$ 48,990,000	$ 3,148,000	$ 185,087,000	$ 135,215,000
Restricted Stock/Unit Plan, and Management Incentive Plan
Class of Stock [Line Items]
Common stock issued (in shares)	47,000
Dividend Reinvestment and Stock Purchase Plan
Class of Stock [Line Items]
Common stock issued (in shares)	49,500
Common stock issued, amount	$ 3,100,000
Equity Shelf Program
Class of Stock [Line Items]
Sale of stock, amount of common stock offered for sale (up to)							$ 300,000,000
Gross proceeds	46,448,484				$ 299,999,974
Less: agent commissions	(464,485)				(3,000,000)
Net proceeds	$ 45,983,999				$ 296,999,974
Number of shares sold (in shares)	705,957				4,102,414
Weighted average price per share	$ 65.80				$ 73.13
Equity Shelf Program | Subsequent Event
Class of Stock [Line Items]
Sale of stock, amount of common stock offered for sale (up to)						$ 500,000,000

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Debt - Schedule of Carrying Amounts and Estimated Fair Values of Long-Term Debt (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Less: current maturities	$ (67,334)	$ (40,433)
Long-term debt, less current maturities	2,696,570	2,732,200
Long-term Debt, Current and Noncurrent Abstract
Less: current maturities	(67,334)	(40,433)
Long-term debt, less current maturities	2,696,570	2,732,200
Southwest Gas Corporation
Debt Instrument [Line Items]
Less: current maturities	(25,000)	0
Long-term debt, less current maturities	2,413,588	2,438,206
Long-term Debt, Current and Noncurrent Abstract
Less: current maturities	(25,000)	0
Long-term debt, less current maturities	$ 2,413,588	2,438,206
Debentures | Notes, 6.1%, due 2041 | Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	6.10%
Debentures | Notes, 3.875%, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Debt instrument interest rate	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 | 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%
Carrying Amount
Debt Instrument [Line Items]
Less: current maturities	$ (67,334)	(40,433)
Long-term debt, less current maturities	2,696,570	2,732,200
Long-term Debt, Current and Noncurrent Abstract
Less: current maturities	(67,334)	(40,433)
Long-term debt, less current maturities	2,696,570	2,732,200
Carrying Amount | Southwest Gas Corporation
Debt Instrument [Line Items]
Less: current maturities	(25,000)	0
Long-term debt, less current maturities	2,413,588	2,438,206
Long-term Debt, Current and Noncurrent Abstract
Less: current maturities	(25,000)	0
Long-term debt, less current maturities	2,413,588	2,438,206
Long-term debt	2,438,588	2,438,206
Carrying Amount | Centuri
Debt Instrument [Line Items]
Less: current maturities	(42,334)	(40,433)
Long-term debt, less current maturities	282,982	293,994
Unamortized debt issuance costs	(750)	(820)
Long-term Debt, Current and Noncurrent Abstract
Less: current maturities	(42,334)	(40,433)
Long-term debt, less current maturities	282,982	293,994
Long-term debt	325,316	334,427
Centuri secured revolving credit facility	221,918	225,828
Carrying Amount | Centuri secured revolving credit facility | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	26,163	26,626
Carrying Amount | Centuri term loan facility | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	222,668	226,648
Carrying Amount | Centuri other debt obligations | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri other debt obligations	77,235	81,973
Carrying Amount | Debentures | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	2,089,999	2,089,678
Unamortized discount and debt issuance costs	(17,501)	(17,822)
Carrying Amount | Debentures | Notes, 6.1%, due 2041 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	125,000	125,000
Carrying Amount | Debentures | Notes, 3.875%, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	250,000	250,000
Carrying Amount | Debentures | Notes, 4.875%, due 2043 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	250,000	250,000
Carrying Amount | Debentures | Notes, 3.8%, due 2046 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	300,000	300,000
Carrying Amount | Debentures | Notes, 3.7%, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	300,000	300,000
Carrying Amount | Debentures | Notes, 4.15%, due 2049 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	300,000	300,000
Carrying Amount | Debentures | Notes, 2.2%, due 2030 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	450,000	450,000
Carrying Amount | Debentures | 8% Series, due 2026 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	75,000	75,000
Carrying Amount | Debentures | Medium-term notes, 7.78% series, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	25,000	25,000
Carrying Amount | Debentures | Medium-term notes, 7.92% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	25,000	25,000
Carrying Amount | Debentures | Medium-term notes, 6.76% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable	7,500	7,500
Carrying Amount | Debentures | Revolving credit facility and commercial paper | Southwest Gas Corporation
Debt Instrument [Line Items]
Line of credit facility	150,000	150,000
Carrying Amount | Industrial development revenue bonds | Southwest Gas Corporation
Debt Instrument [Line Items]
Unamortized discount and debt issuance costs	(1,411)	(1,472)
Unsecured debt	198,589	198,528
Carrying Amount | Industrial development revenue bonds | Tax-exempt Series A, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Carrying Amount | Industrial development revenue bonds | 2003 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Carrying Amount | Industrial development revenue bonds | 2008 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Carrying Amount | Industrial development revenue bonds | 2009 Series A, due 2039 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Fair Value | Centuri secured revolving credit facility | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	26,180	26,645
Fair Value | Centuri term loan facility | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri secured revolving credit facility	225,269	230,824
Fair Value | Centuri other debt obligations | Centuri
Long-term Debt, Current and Noncurrent Abstract
Centuri other debt obligations	78,378	84,246
Fair Value | Debentures | Notes, 6.1%, due 2041 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	160,651	174,858
Fair Value | Debentures | Notes, 3.875%, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	256,693	258,825
Fair Value | Debentures | Notes, 4.875%, due 2043 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	288,500	317,190
Fair Value | Debentures | Notes, 3.8%, due 2046 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	306,261	347,046
Fair Value | Debentures | Notes, 3.7%, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	324,069	344,553
Fair Value | Debentures | Notes, 4.15%, due 2049 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	324,183	370,278
Fair Value | Debentures | Notes, 2.2%, due 2030 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	438,912	474,552
Fair Value | Debentures | 8% Series, due 2026 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	95,894	99,723
Fair Value | Debentures | Medium-term notes, 7.78% series, due 2022 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	26,201	26,663
Fair Value | Debentures | Medium-term notes, 7.92% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	32,138	33,802
Fair Value | Debentures | Medium-term notes, 6.76% series, due 2027 | Southwest Gas Corporation
Debt Instrument [Line Items]
Notes payable, fair value disclosure	9,127	9,613
Fair Value | Debentures | Revolving credit facility and commercial paper | Southwest Gas Corporation
Debt Instrument [Line Items]
Line of credit facility, fair value	150,000	150,000
Fair Value | Industrial development revenue bonds | Tax-exempt Series A, due 2028 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Fair Value | Industrial development revenue bonds | 2003 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt	50,000	50,000
Fair Value | Industrial development revenue bonds | 2008 Series A, due 2038 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt, fair value	50,000	50,000
Fair Value | Industrial development revenue bonds | 2009 Series A, due 2039 | Southwest Gas Corporation
Debt Instrument [Line Items]
Unsecured debt, fair value	$ 50,000	$ 50,000

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Debt - Narratives (Details) - USD ($)	1 Months Ended	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Debt Instrument [Line Items]
Current maturities of long-term debt	$ 67,334,000	$ 67,334,000	$ 40,433,000
Short term borrowings outstanding	310,000,000	310,000,000	107,000,000
Southwest Gas Corporation
Debt Instrument [Line Items]
Current maturities of long-term debt	25,000,000	25,000,000	0
Short term borrowings outstanding	267,000,000	267,000,000	$ 57,000,000
Southwest Gas Corporation | $250 Million Term Loan
Debt Instrument [Line Items]
Debt instrument, face amount	$ 250,000,000	$ 250,000,000
Effective interest rate (in percent)	0.77%	0.77%
Debt covenant, ratio of funded debt to total capitalization	0.70	0.70
Southwest Gas Corporation | Southwest Gas Credit Facility
Debt Instrument [Line Items]
Line of credit designated as long term debt	$ 150,000,000	$ 150,000,000
Line of credit designated for working capital purposes	250,000,000	250,000,000
Long-term debt	150,000,000	150,000,000
Current maturities of long-term debt	17,000,000	17,000,000
Southwest Gas Corporation | Commercial Paper Program
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	50,000,000	50,000,000
Borrowings outstanding under facility	$ 50,000,000	$ 50,000,000
Southwest Gas Corporation | LIBOR | Minimum | $250 Million Term Loan
Debt Instrument [Line Items]
Applicable margin	0.55%
Southwest Gas Corporation | LIBOR | Maximum | $250 Million Term Loan
Debt Instrument [Line Items]
Applicable margin	1.00%
Southwest Gas Corporation | LIBOR | Southwest Gas Credit Facility
Debt Instrument [Line Items]
Applicable margin		1.00%
Southwest Gas Corporation | Alternative base rate | $250 Million Term Loan
Debt Instrument [Line Items]
Applicable margin		0.00%
Southwest Gas Corporation | Alternative base rate | Southwest Gas Credit Facility
Debt Instrument [Line Items]
Applicable margin		0.00%
Centuri | Secured Revolving Credit Facility and Term Loan
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	$ 590,000,000	$ 590,000,000
Borrowings outstanding under facility	249,000,000	249,000,000
Debt secured by assets	1,300,000,000	1,300,000,000
Centuri | Line of Credit
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	325,000,000	325,000,000
Centuri | Centuri term loan facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	265,000,000	265,000,000
$400 Million Credit Facility | Southwest Gas Corporation
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	400,000,000	400,000,000
$100 Million Credit Facility
Debt Instrument [Line Items]
Credit facility maximum borrowing capacity	100,000,000	100,000,000
Borrowings outstanding under facility	$ 43,000,000	$ 43,000,000

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Other Comprehensive Income and Accumulated Other Comprehensive Income - Related Tax Effects Allocated to OCI (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, net of tax	$ 823
Other comprehensive income (loss), before tax	3,181	$ (1,816)	$ (1,162)	$ (10,249)
Other comprehensive income (loss), tax	(566)	(525)	1,847	1,799
Total other comprehensive income (loss), net of tax	$ 2,615	(2,341)	$ 685	(8,450)
Effective income tax rate	24.00%		24.00%
Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	$ 2,358	2,189	$ (7,703)	(7,491)
Other comprehensive income (loss), tax	(566)	(525)	1,847	1,799
Total other comprehensive income (loss), net of tax	1,792	1,664	(5,856)	(5,692)
Amortization of prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	240	289	1,106	1,243
Reclassification from AOCI, tax	(58)	(69)	(266)	(298)
Reclassification from AOCI, net of tax	182	220	840	945
Other comprehensive income (loss), before tax	240
Other comprehensive income (loss), tax	(58)
Total other comprehensive income (loss), net of tax	182
Amortization of prior service cost | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	240
Other comprehensive income (loss), tax	(58)
Total other comprehensive income (loss), net of tax	182
Amortization of net actuarial (gain)/loss
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax			(57,539)	(71,087)
Other comprehensive income (loss) before reclassifications, tax			13,809	17,061
Other comprehensive income (loss) before reclassifications, net of tax			(43,730)	(54,026)
Reclassification from AOCI, before Tax	11,149	9,458	39,521	26,990
Reclassification from AOCI, tax	(2,675)	(2,270)	(9,484)	(6,477)
Reclassification from AOCI, net of tax	8,474	7,188	30,037	20,513
Other comprehensive income (loss), before tax	11,149
Other comprehensive income (loss), tax	(2,675)
Total other comprehensive income (loss), net of tax	8,474
Amortization of net actuarial (gain)/loss | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	11,149
Other comprehensive income (loss), tax	(2,675)
Total other comprehensive income (loss), net of tax	8,474
Regulatory adjustment
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	(9,575)	(8,395)	6,255	33,896
Reclassification from AOCI, tax	2,298	2,015	(1,502)	(8,136)
Reclassification from AOCI, net of tax	(7,277)	(6,380)	4,753	25,760
Other comprehensive income (loss), before tax	(9,575)
Other comprehensive income (loss), tax	2,298
Total other comprehensive income (loss), net of tax	(7,277)
Regulatory adjustment | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	(9,575)
Other comprehensive income (loss), tax	2,298
Total other comprehensive income (loss), net of tax	(7,277)
Prior service cost
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax			0	(1,878)
Other comprehensive income (loss) before reclassifications, tax			0	452
Other comprehensive income (loss) before reclassifications, net of tax			0	(1,426)
Defined Benefit Plans
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	1,814	1,352	(10,657)	(10,836)
Other comprehensive income (loss), tax	(435)	(324)	2,557	2,602
Total other comprehensive income (loss), net of tax	1,379	1,028	(8,100)	(8,234)
Defined Benefit Plans | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss), before tax	1,814
Other comprehensive income (loss), tax	(435)
Total other comprehensive income (loss), net of tax	1,379
FSIRS
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	544	837	2,954	3,345
Reclassification from AOCI, tax	(131)	(201)	(710)	(803)
Reclassification from AOCI, net of tax	413	636	2,244	2,542
Other comprehensive income (loss), before tax	544	837	2,954	3,345
Other comprehensive income (loss), tax	(131)	(201)	(710)	(803)
Total other comprehensive income (loss), net of tax	413	636	2,244	2,542
FSIRS | Southwest Gas Corporation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from AOCI, before Tax	544
Reclassification from AOCI, tax	(131)
Reclassification from AOCI, net of tax	413
Other comprehensive income (loss), before tax	544
Other comprehensive income (loss), tax	(131)
Total other comprehensive income (loss), net of tax	413
Foreign Currency Items
Accumulated Other Comprehensive Income (Loss) [Line Items]
Other comprehensive income (loss) before reclassifications, before tax	823	(4,005)	6,541	(2,758)
Other comprehensive income (loss) before reclassifications, tax	0	0	0	0
Other comprehensive income (loss) before reclassifications, net of tax	$ 823	$ (4,005)	$ 6,541	$ (2,758)

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Other Comprehensive Income and Accumulated Other Comprehensive Income - Additional Information (Details) $ in Millions	Mar. 31, 2021 USD ($)
Equity [Abstract]
Amount of FSIRS existing AOCI losses expected to reclassified income in next twelve months	$ 1.7

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Other Comprehensive Income and Accumulated Other Comprehensive Income - AOCI Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent	$ 2,674,953
Other comprehensive income (loss) before reclassifications, net of tax	823
Other comprehensive income (loss), before tax	3,181	$ (1,816)	$ (1,162)	$ (10,249)
Other comprehensive income (loss), tax	(566)	(525)	1,847	1,799
Total other comprehensive income (loss), net of tax	2,615	(2,341)	685	(8,450)
Ending balance, attributable to parent	$ 2,773,722		$ 2,773,722
Effective income tax rate	24.00%		24.00%
Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	$ (77,720)
Beginning balance, tax	18,653
Beginning balance	(59,067)
Other comprehensive income (loss), before tax	1,814	1,352	$ (10,657)	(10,836)
Other comprehensive income (loss), tax	(435)	(324)	2,557	2,602
Total other comprehensive income (loss), net of tax	1,379	1,028	(8,100)	(8,234)
Ending balance, before tax	(75,906)		(75,906)
Ending balance, tax	18,218		18,218
Ending balance	(57,688)		(57,688)
Amortization of prior service cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	240	289	1,106	1,243
Reclassification from AOCI, tax	(58)	(69)	(266)	(298)
Reclassification from AOCI, net of tax	182	220	840	945
Other comprehensive income (loss), before tax	240
Other comprehensive income (loss), tax	(58)
Total other comprehensive income (loss), net of tax	182
Amortization of net actuarial loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss) before reclassifications, before tax			(57,539)	(71,087)
Other comprehensive income (loss) before reclassifications, net of tax			(43,730)	(54,026)
Reclassification from AOCI, before Tax	11,149	9,458	39,521	26,990
Reclassification from AOCI, tax	(2,675)	(2,270)	(9,484)	(6,477)
Reclassification from AOCI, net of tax	8,474	7,188	30,037	20,513
Other comprehensive income (loss), before tax	11,149
Other comprehensive income (loss), tax	(2,675)
Total other comprehensive income (loss), net of tax	8,474
Regulatory adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Reclassification from AOCI, before Tax	(9,575)	(8,395)	6,255	33,896
Reclassification from AOCI, tax	2,298	2,015	(1,502)	(8,136)
Reclassification from AOCI, net of tax	(7,277)	(6,380)	4,753	25,760
Other comprehensive income (loss), before tax	(9,575)
Other comprehensive income (loss), tax	2,298
Total other comprehensive income (loss), net of tax	(7,277)
FSIRS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	(2,719)
Beginning balance, tax	651
Beginning balance	(2,068)
Reclassification from AOCI, before Tax	544	837	2,954	3,345
Reclassification from AOCI, tax	(131)	(201)	(710)	(803)
Reclassification from AOCI, net of tax	413	636	2,244	2,542
Other comprehensive income (loss), before tax	544	837	2,954	3,345
Other comprehensive income (loss), tax	(131)	(201)	(710)	(803)
Total other comprehensive income (loss), net of tax	413	636	2,244	2,542
Ending balance, before tax	(2,175)		(2,175)
Ending balance, tax	520		520
Ending balance	(1,655)		(1,655)
Foreign Currency Items
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, before tax	132
Beginning balance	132
Other comprehensive income (loss) before reclassifications, before tax	823
Other comprehensive income (loss) before reclassifications, net of tax	823
Ending balance, before tax	955		955
Ending balance	955		955
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	2,615
AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(61,003)	(56,732)	(59,073)
Ending balance	(58,388)	(59,073)	(58,388)	(59,073)
Southwest Gas Corporation
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance			2,114,276
Beginning balance, attributable to parent	2,233,468
Other comprehensive income (loss), before tax	2,358	2,189	(7,703)	(7,491)
Other comprehensive income (loss), tax	(566)	(525)	1,847	1,799
Total other comprehensive income (loss), net of tax	1,792	1,664	(5,856)	(5,692)
Ending balance, attributable to parent	2,374,124		2,374,124
Ending balance	2,374,124	2,114,276	2,374,124	2,114,276
Southwest Gas Corporation | Defined Benefit Plans
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent, before tax	(77,720)
Beginning balance, attributable to parent, tax	18,653
Beginning balance, attributable to parent	(59,067)
Other comprehensive income (loss), before tax	1,814
Other comprehensive income (loss), tax	(435)
Total other comprehensive income (loss), net of tax	1,379
Ending balance, attributable to parent, before tax	(75,906)		(75,906)
Ending balance, attributable to parent, tax	18,218		18,218
Ending balance, attributable to parent	(57,688)		(57,688)
Southwest Gas Corporation | Amortization of prior service cost
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	240
Other comprehensive income (loss), tax	(58)
Total other comprehensive income (loss), net of tax	182
Southwest Gas Corporation | Amortization of net actuarial loss
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	11,149
Other comprehensive income (loss), tax	(2,675)
Total other comprehensive income (loss), net of tax	8,474
Southwest Gas Corporation | Regulatory adjustment
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Other comprehensive income (loss), before tax	(9,575)
Other comprehensive income (loss), tax	2,298
Total other comprehensive income (loss), net of tax	(7,277)
Southwest Gas Corporation | FSIRS
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance, attributable to parent, before tax	(2,719)
Beginning balance, attributable to parent, tax	651
Beginning balance, attributable to parent	(2,068)
Reclassification from AOCI, before Tax	544
Reclassification from AOCI, tax	(131)
Reclassification from AOCI, net of tax	413
Other comprehensive income (loss), before tax	544
Other comprehensive income (loss), tax	(131)
Total other comprehensive income (loss), net of tax	413
Ending balance, attributable to parent, before tax	(2,175)		(2,175)
Ending balance, attributable to parent, tax	520		520
Ending balance, attributable to parent	(1,655)		(1,655)
Southwest Gas Corporation | AOCI Attributable to Parent
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning balance	(61,135)	(55,151)	(53,487)
Beginning balance, attributable to parent	(61,135)
Ending balance, attributable to parent	(59,343)		(59,343)
Ending balance	$ (59,343)	$ (53,487)	$ (59,343)	$ (53,487)

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Other Comprehensive Income and Accumulated Other Comprehensive Income - Amounts Recognized Before Tax, Defined Benefit Plans (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Equity [Abstract]
Net actuarial loss	$ (491,634)	$ (502,783)
Prior service cost	(2,247)	(2,487)
Less: amount recognized in regulatory assets	417,975	427,550
Recognized in AOCI	$ (75,906)	$ (77,720)

XML

Segment Information - Accounts Receivable for Services (Details) - USD ($) $ in Thousands	Mar. 31, 2021	Dec. 31, 2020
Centuri
Segment Reporting Information [Line Items]
Centuri accounts receivable for services provided to Southwest	$ 11,344	$ 13,956

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Segment Information - Narratives (Details)	3 Months Ended
	Mar. 31, 2021 Segment
Segment Reporting [Abstract]
Number of reportable segments	2

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Segment Information - Schedule of Reporting Information (Details) - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Revenues	$ 885,907	$ 836,320	$ 3,348,460	$ 3,122,698
Segment net income (loss)	117,293	72,542	277,075	191,669
Revenues from external customers
Segment Reporting Information [Line Items]
Revenues	861,704	803,118	3,222,600	2,969,443
Intersegment revenues
Segment Reporting Information [Line Items]
Revenues	24,203	33,202	125,860	153,255
Segment net income (loss)	(563)	(853)	(1,366)	(1,943)
Natural Gas Operations
Segment Reporting Information [Line Items]
Revenues	521,932	502,827	1,369,690	1,351,089
Segment net income (loss)	118,715	83,599	194,234	143,381
Natural Gas Operations | Revenues from external customers
Segment Reporting Information [Line Items]
Revenues	521,932	502,827	1,369,690	1,351,089
Natural Gas Operations | Intersegment revenues
Segment Reporting Information [Line Items]
Revenues	0	0	0	0
Utility Infrastructure Services
Segment Reporting Information [Line Items]
Revenues	363,975	333,493	1,978,770	1,771,609
Segment net income (loss)	(859)	(10,204)	84,207	50,231
Utility Infrastructure Services | Revenues from external customers
Segment Reporting Information [Line Items]
Revenues	339,772	300,291	1,852,910	1,618,354
Utility Infrastructure Services | Intersegment revenues
Segment Reporting Information [Line Items]
Revenues	$ 24,203	$ 33,202	$ 125,860	$ 153,255