Condensed Consolidated Balance Sheets - USD ($) $ in Thousands	Mar. 31, 2018	Dec. 31, 2017
Utility plant:
Gas plant	$ 6,709,858	$ 6,629,644
Less: accumulated depreciation	(2,248,307)	(2,231,242)
Construction work in progress	142,840	125,248
Net utility plant	4,604,391	4,523,650
Other property and investments	442,771	428,180
Current assets:
Cash and cash equivalents	65,115	43,622
Accounts receivable, net of allowances	335,982	347,375
Accrued utility revenue	47,300	78,200
Income taxes receivable, net	15,549	7,960
Deferred purchased gas costs	18,739	14,581
Prepaids and other current assets	181,248	165,294
Total current assets	663,933	657,032
Noncurrent assets:
Goodwill	176,485	179,314
Deferred income taxes	1,371	1,480
Deferred charges and other assets	438,682	447,410
Total noncurrent assets	616,538	628,204
Total assets	6,327,633	6,237,066
Capitalization:
Common stock	49,967	49,720
Additional paid-in capital	965,480	955,332
Accumulated other comprehensive income (loss), net	(56,363)	(47,682)
Retained earnings	920,454	857,398
Total Southwest Gas Holdings, Inc./Total Southwest Gas Corporation equity	1,879,538	1,814,768
Noncontrolling interest	(3,162)	(2,365)
Total equity	1,876,376	1,812,403
Long-term debt, less current maturities	1,998,127	1,798,576
Total capitalization	3,874,503	3,610,979
Current liabilities:
Current maturities of long-term debt	24,867	25,346
Short-term debt	22,500	214,500
Accounts payable	175,905	228,315
Customer deposits	69,610	69,781
Income taxes payable	12,906	5,946
Accrued general taxes	63,307	43,879
Accrued interest	24,906	17,870
Deferred purchased gas costs	371	6,841
Other current liabilities	208,479	203,403
Total current liabilities	602,851	815,881
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits	500,289	476,960
Accumulated removal costs	317,000	315,000
Other deferred credits and other long-term liabilities	1,032,990	1,018,246
Total deferred income taxes and other credits	1,850,279	1,810,206
Total capitalization and liabilities	6,327,633	6,237,066
Southwest Gas Corporation [Member]
Utility plant:
Gas plant	6,709,858	6,629,644
Less: accumulated depreciation	(2,248,307)	(2,231,242)
Construction work in progress	142,840	125,248
Net utility plant	4,604,391	4,523,650
Other property and investments	118,449	119,114
Current assets:
Cash and cash equivalents	45,789	37,946
Accounts receivable, net of allowances	147,949	119,748
Accrued utility revenue	47,300	78,200
Deferred purchased gas costs	18,739	14,581
Receivable from parent	216
Prepaids and other current assets	170,595	153,771
Total current assets	430,588	404,246
Noncurrent assets:
Goodwill	10,095	10,095
Deferred charges and other assets	418,833	425,564
Total noncurrent assets	428,928	435,659
Total assets	5,582,356	5,482,669
Capitalization:
Common stock	49,112	49,112
Additional paid-in capital	948,199	948,767
Accumulated other comprehensive income (loss), net	(54,843)	(47,073)
Retained earnings	736,676	659,193
Total Southwest Gas Holdings, Inc./Total Southwest Gas Corporation equity	1,679,144	1,609,999
Long-term debt, less current maturities	1,706,994	1,521,031
Total capitalization	3,386,138	3,131,030
Current liabilities:
Short-term debt		191,000
Accounts payable	117,910	158,474
Customer deposits	69,610	69,781
Income taxes payable	13,019	4,971
Accrued general taxes	63,307	43,879
Accrued interest	24,823	17,171
Deferred purchased gas costs	371	6,841
Payable to parent		194
Other current liabilities	122,647	108,785
Total current liabilities	411,687	601,096
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits	464,403	445,243
Accumulated removal costs	317,000	315,000
Other deferred credits and other long-term liabilities	1,003,128	990,300
Total deferred income taxes and other credits	1,784,531	1,750,543
Total capitalization and liabilities	$ 5,582,356	$ 5,482,669