Debt (Tables)

12 Months Ended

Dec. 31, 2022

Debt Disclosure [Abstract]

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

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

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

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

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

Summary of Effective Interest Rates on Variable-Rate IDRBs

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

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

Estimated Maturities of Long-Term Debt

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

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