CONDENSED CONSOLIDATED STATEMENTS OF CASH FLOWS - USD ($) $ in Thousands	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Mar. 31, 2020	Mar. 31, 2019
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	$ 73,005	$ 95,384	$ 194,268	$ 198,742
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	87,653	77,539	313,351	264,273
Deferred income taxes	25,309	24,923	54,548	52,736
Changes in current assets and liabilities:
Accounts receivable, net of allowances	45,837	(15,562)	7,154	(40,282)
Accrued utility revenue	31,000	30,200	(1,100)	300
Deferred purchased gas costs	10,155	(67,863)	19,527	25,339
Accounts payable	(60,723)	(12,643)	(49,945)	47,632
Accrued taxes	30,377	25,400	10,220	(5,331)
Other current assets and liabilities	76,453	47,848	102,742	(5,582)
Gains on sale of equipment	(28)	(233)	(5,268)	(1,706)
Changes in undistributed stock compensation	2,816	3,188	6,524	7,438
Equity AFUDC	(1,061)	(960)	(4,262)	(4,358)
Changes in deferred charges and other assets	6,495	(16,328)	1,772	(20,221)
Changes in other liabilities and deferred credits	(55,722)	(2,782)	(65,704)	17,420
Net cash provided by operating activities	271,566	188,111	583,827	536,400
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(210,655)	(210,662)	(938,141)	(822,034)
Acquisition of businesses, net of cash acquired	0	0	(47,638)	(247,164)
Changes in customer advances	5,434	3,078	21,357	13,503
Other	4,430	262	19,321	3,200
Net cash used in investing activities	(200,791)	(207,322)	(945,101)	(1,052,495)
CASH FLOW FROM FINANCING ACTIVITIES:
Issuance of common stock, net	3,148	25,879	135,215	369,061
Dividends paid	(30,006)	(27,602)	(118,531)	(104,003)
Issuance of long-term debt, net	99,978	29,666	601,908	259,456
Retirement of long-term debt	(75,168)	(31,160)	(257,797)	(247,816)
Change in credit facility and commercial paper	0	0	0	111,000
Change in short-term debt	(54,000)	36,000	(31,000)	165,500
Principal payments on finance lease obligations	(51)	(70)	(193)	(553)
Withholding remittance - share-based compensation	(2,736)	(1,838)	(2,756)	(2,096)
Other	(199)	(53)	(1,422)	(2,460)
Net cash provided by (used in) financing activities	(59,034)	30,822	325,424	548,089
Effects of currency translation on cash and cash equivalents	(315)	65	(222)	(72)
Change in cash and cash equivalents	11,426	11,676	(36,072)	31,922
Cash and cash equivalents at beginning of period	49,539	85,361	97,037	65,115
Cash and cash equivalents at end of period	60,965	97,037	60,965	97,037
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	13,073	15,850	99,481	89,118
Income taxes paid (received), net	(20,064)	454	(17,766)	(2,743)
Southwest Gas Corporation
CASH FLOW FROM OPERATING ACTIVITIES:
Net income	83,599	103,389	143,381	151,882
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	64,725	57,612	222,733	199,467
Deferred income taxes	7,707	26,270	15,118	50,593
Changes in current assets and liabilities:
Accounts receivable, net of allowances	1,975	(30,414)	21,652	(22,522)
Accrued utility revenue	31,000	30,200	(1,100)	300
Deferred purchased gas costs	10,155	(67,863)	19,527	25,339
Accounts payable	(41,899)	(39,574)	(29,798)	18,398
Accrued taxes	53,335	28,704	33,526	(17,504)
Other current assets and liabilities	99,257	81,625	106,803	(12,982)
Changes in undistributed stock compensation	2,496	2,597	5,045	5,834
Equity AFUDC	(1,061)	(960)	(4,262)	(4,358)
Changes in deferred charges and other assets	3,658	(18,238)	(9,871)	(23,289)
Changes in other liabilities and deferred credits	(55,910)	(2,977)	(66,294)	16,805
Net cash provided by operating activities	259,037	170,371	456,460	387,963
CASH FLOW FROM INVESTING ACTIVITIES:
Construction expenditures and property additions	(173,353)	(163,636)	(788,465)	(714,762)
Changes in customer advances	5,433	3,078	21,356	13,503
Other	(31)	(78)	(48)	(357)
Net cash used in investing activities	(167,951)	(160,636)	(767,157)	(701,616)
CASH FLOW FROM FINANCING ACTIVITIES:
Contributions from parent	50,000	22,842	187,094	136,391
Dividends paid	(25,200)	(23,500)	(97,600)	(89,500)
Issuance of long-term debt, net	0	0	297,222	0
Change in credit facility and commercial paper	0	0	0	111,000
Change in short-term debt	(97,000)	36,000	(91,000)	188,000
Withholding remittance - share-based compensation	(2,736)	(1,838)	(2,756)	(2,096)
Other	(115)	(53)	(887)	(783)
Net cash provided by (used in) financing activities	(75,051)	33,451	292,073	343,012
Change in cash and cash equivalents	16,035	43,186	(18,624)	29,359
Cash and cash equivalents at beginning of period	40,489	31,962	75,148	45,789
Cash and cash equivalents at end of period	56,524	75,148	56,524	75,148
SUPPLEMENTAL INFORMATION:
Interest paid, net of amounts capitalized	10,204	11,585	87,277	75,094
Income taxes paid (received), net	$ (22,962)	$ (22)	$ 700	$ (5,878)