CONDENSED CONSOLIDATED STATEMENTS OF INCOME - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Operating revenues:
Regulated operations revenues	$ 367,122	$ 255,848	$ 1,550,684	$ 1,070,576	$ 2,001,898	$ 1,445,066
Utility infrastructure services revenues	758,466	632,848	1,988,433	1,525,448	2,621,646	2,065,038
Total operating revenues	1,125,588	888,696	3,539,117	2,596,024	4,623,544	3,510,104
Operating expenses:
Net cost of gas sold	100,991	63,710	547,769	296,227	682,449	374,449
Operations and maintenance	154,236	122,927	479,330	334,450	618,026	437,602
Depreciation and amortization	116,933	91,380	347,589	267,670	450,960	354,688
Taxes other than income taxes	23,356	20,109	70,778	60,134	90,987	76,087
Utility infrastructure services expenses	680,135	567,270	1,829,560	1,381,524	2,403,503	1,858,464
Total operating expenses	1,075,651	865,396	3,275,026	2,340,005	4,245,925	3,101,290
Operating income (loss)	49,937	23,300	264,091	256,019	377,619	408,814
Other income and (expenses):
Net interest deductions	(64,373)	(31,298)	(165,942)	(81,201)	(203,939)	(109,537)
Other income (deductions)	1,593	(3,112)	2	(3,975)	478	282
Total other income and (expenses)	(62,780)	(34,410)	(165,940)	(85,176)	(203,461)	(109,255)
Income (loss) before income taxes	(12,843)	(11,110)	98,151	170,843	174,158	299,559
Income tax expense (benefit)	(1,525)	(1,816)	18,300	34,818	23,130	58,498
Net income (loss)	(11,318)	(9,294)	79,851	136,025	151,028	241,061
Net income attributable to noncontrolling interests	991	2,282	2,557	5,189	3,791	6,681
Net income (loss) attributable to Southwest Gas Holdings, Inc.	$ (12,309)	$ (11,576)	$ 77,294	$ 130,836	$ 147,237	$ 234,380
Earnings (loss) per share:
Basic (in USD per share)	$ (0.18)	$ (0.19)	$ 1.19	$ 2.23	$ 2.30	$ 4.03
Diluted (in USD per share)	$ (0.18)	$ (0.19)	$ 1.19	$ 2.23	$ 2.30	$ 4.02
Weighted average shares:
Basic (in shares)	67,157	59,688	65,004	58,639	63,905	58,209
Diluted (in shares)	67,325	59,816	65,148	58,742	64,051	58,312