Debt (Tables)

3 Months Ended

Mar. 31, 2024

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.

	March 31, 2024				December 31, 2023
	Carrying Amount		Fair Value		Carrying Amount		Fair Value
(Thousands of dollars)
Southwest Gas Corporation:
Debentures:
8% Series, due 2026	$	75,000	$	78,087	$	75,000	$	79,502
Medium-term notes, 7.92% series, due 2027	25,000		26,470		25,000		26,883
Medium-term notes, 6.76% series, due 2027	7,500		7,703		7,500		7,800
Notes, 5.8%, due 2027	300,000		306,630		300,000		309,180
Notes, 3.7%, due 2028	300,000		285,690		300,000		285,300
Notes, 5.45%, due 2028	300,000		304,920		300,000		307,170
Notes, 2.2%, due 2030	450,000		381,555		450,000		382,635
Notes, 4.05%, due 2032	600,000		549,840		600,000		563,940
Notes, 6.1%, due 2041	125,000		129,113		125,000		126,238
Notes, 4.875%, due 2043	250,000		215,200		250,000		214,050
Notes, 3.8%, due 2046	300,000		224,970		300,000		225,240
Notes, 4.15%, due 2049	300,000		232,860		300,000		236,370
Notes, 3.18%, due 2051	300,000		196,110		300,000		197,760
Unamortized discount and debt issuance costs	(28,828)				(29,594)
	3,303,672				3,302,906
Revolving credit facility and commercial paper	—		—		—		—
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	(1,261)				(1,363)
	198,739				198,637
Less: current maturities	—				—
Southwest Gas Corporation total long-term debt, less current maturities	3,502,411				3,501,543
Southwest Gas Holdings, Inc.:
Centuri secured term loan facility	991,375		991,375		994,238		996,723
Centuri secured revolving credit facility	125,229		125,324		77,121		77,205
Other debt obligations	88,905		85,024		96,599		92,209
Unamortized discount and debt issuance costs	(16,192)				(17,111)
Less: current maturities	(42,770)				(42,552)
Southwest Gas Holdings, Inc. total long-term debt, less current maturities	$	4,648,958			$	4,609,838