Debt (Tables)

9 Months Ended

Sep. 30, 2021

Debt Disclosure [Abstract]

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

	September 30, 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	$	167,755	$	125,000	$	174,858
Notes, 3.875%, due 2022	250,000		252,208		250,000		258,825
Notes, 4.875%, due 2043	250,000		307,385		250,000		317,190
Notes, 3.8%, due 2046	300,000		326,058		300,000		347,046
Notes, 3.7%, due 2028	300,000		331,536		300,000		344,553
Notes, 4.15%, due 2049	300,000		343,950		300,000		370,278
Notes, 2.2%, due 2030	450,000		447,287		450,000		474,552
Notes, 3.18%, due 2051	300,000		291,351		—		—
8% Series, due 2026	75,000		94,752		75,000		99,723
Medium-term notes, 7.78% series, due 2022	25,000		25,513		25,000		26,663
Medium-term notes, 7.92% series, due 2027	25,000		31,936		25,000		33,802
Medium-term notes, 6.76% series, due 2027	7,500		9,116		7,500		9,613
Unamortized discount and debt issuance costs	(20,727)				(17,822)
	2,386,773				2,089,678
Revolving credit facility and commercial paper	—		—		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	(1,916)				(1,472)
	198,084				198,528
Less: current maturities	(275,000)				—
Long-term debt, less current maturities - Southwest Gas Corporation	$	2,309,857			$	2,438,206
Centuri:
Centuri term loan facility	$	1,145,000	$	1,146,431	$	226,648	$	230,824
Unamortized debt issuance costs	(25,385)				(820)
	1,119,615				225,828
Centuri secured revolving credit facility	112,236		112,348		26,626		26,645
Centuri other debt obligations	54,346		52,682		81,973		84,246
Less: current maturities	(22,271)				(40,433)
Long-term debt, less current maturities - Centuri	$	1,263,926			$	293,994
Consolidated Southwest Gas Holdings, Inc.:
Southwest Gas Corporation long-term debt	$	2,584,857			$	2,438,206
Centuri long-term debt	1,286,197				334,427
Less: current maturities	(297,271)				(40,433)
Long-term debt, less current maturities - Southwest Gas Holdings, Inc.	$	3,573,783			$	2,732,200