Condensed Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Utility plant:
Gas plant	$ 5,158,793	$ 5,019,500
Less: accumulated depreciation	(1,840,092)	(1,750,795)
Acquisition adjustments, net	776	911
Construction work in progress	108,913	74,178
Net utility plant	3,428,390	3,343,794
Other property and investments	257,338	242,096
Current assets:
Cash and cash equivalents	13,853	25,530
Accounts receivable, net of allowances	155,603	196,913
Accrued utility revenue	31,300	72,000
Income taxes receivable, net	4,700	2,945
Deferred income taxes	48,365	47,088
Deferred purchased gas costs	2,698	6,031
Prepaids and other current assets	91,676	107,910
Total current assets	348,195	458,417
Deferred charges and other assets	431,132	443,750
Total assets	4,465,055	4,488,057
Capitalization:
Common stock, $1 par (authorized - 60,000,000 shares; issued and outstanding - 46,340,002 and 46,147,788 shares)	47,970	47,778
Additional paid-in capital	835,975	828,777
Accumulated other comprehensive income (loss), net	(47,238)	(50,745)
Retained earnings	525,971	484,369
Total Southwest Gas Corporation equity	1,362,678	1,310,179
Noncontrolling interest	(2,014)	(1,681)
Total equity	1,360,664	1,308,498
Long-term debt, less current maturities	1,280,392	1,268,373
Total capitalization	2,641,056	2,576,871
Current liabilities:
Current maturities of long-term debt	11,052	50,137
Short-term debt	33,000	0
Accounts payable	101,135	155,667
Customer deposits	73,729	77,858
Accrued general taxes	38,359	37,644
Accrued interest	17,067	16,080
Deferred purchased gas costs	16,915	98,957
Other current liabilities	115,136	98,786
Total current liabilities	406,393	535,129
Deferred income taxes and other credits:
Deferred income taxes and investment tax credits	663,315	616,184
Taxes payable	351	551
Accumulated removal costs	272,000	256,000
Other deferred credits	481,940	503,322
Total deferred income taxes and other credits	1,417,606	1,376,057
Total capitalization and liabilities	$ 4,465,055	$ 4,488,057