Quarterly Financial Data (Tables)

12 Months Ended

Dec. 31, 2013

Quarterly Financial Information Disclosure [Abstract]

Schedule of Quarterly Financial Information

	Quarter Ended
	March 31		June 30			September 30			December 31
(Thousands of dollars, except per share amounts)
2013
Operating revenues	$	613,505	$	411,574		$	387,346		$	538,357
Operating income		138,394		28,908			6,141			100,772
Net income (loss)		80,674		10,067			(3,057	)		57,189
Net income (loss) attributable to Southwest Gas Corporation		80,773		10,108			(2,864	)		57,303
Basic earnings (loss) per common share*		1.75		0.22			(0.06	)		1.24
Diluted earnings (loss) per common share*		1.73		0.22			(0.06	)		1.22
2012
Operating revenues	$	657,645	$	409,768		$	371,799		$	488,566
Operating income		134,623		15,380			6,310			115,211
Net income (loss)		78,835		(3,888	)		(4,414	)		62,106
Net income (loss) attributable to Southwest Gas Corporation		78,919		(3,676	)		(4,305	)		62,393
Basic earnings (loss) per common share*		1.71		(0.08	)		(0.09	)		1.35
Diluted earnings (loss) per common share*		1.70		(0.08	)		(0.09	)		1.34
2011
Operating revenues	$	628,440	$	388,505		$	352,592		$	517,651
Operating income		126,335		20,568			1,253			101,924
Net income (loss)		68,354		4,013			(15,747	)		55,143
Net income (loss) attributable to Southwest Gas Corporation		68,549		4,055			(15,641	)		55,324
Basic earnings (loss) per common share*		1.50		0.09			(0.34	)		1.20
Diluted earnings (loss) per common share*		1.48		0.09			(0.34	)		1.19

* The sum of quarterly earnings (loss) per average common share may not equal the annual earnings (loss) per share due to the ongoing change in the weighted-average number of common shares outstanding.