Quarterly Financial Information (Tables)

12 Months Ended

Dec. 31, 2011

Selected Quarterly Financial Information [Abstract]

Summary of unaudited quarterly financial information

Following is a summary of unaudited quarterly financial information:

	First Quarter		Second Quarter		Third Quarter		Fourth Quarter		Year
	(in millions, except per-share amounts)
2011
Revenues	$	470.0	$	222.9	$	146.7	$	354.8	$	1,194.4
Operating income	122.8		73.7		63.8		106.6		366.9
Income from continuing operations	69.9		40.3		36.1		61.6		207.9
Net income attributable to Questar	69.9		40.3		36.1		61.6		207.9
Per-share information attributable to Questar
Basic EPS from continuing operations	$	0.40	$	0.22	$	0.21	$	0.34	$	1.17
Basic EPS attributable to Questar	0.40		0.22		0.21		0.34		1.17
Diluted EPS from continuing operations	0.39		0.22		0.20		0.34		1.16
Diluted EPS attributable to Questar	0.39		0.22		0.20		0.34		1.16
2010
Revenues	$	414.6	$	201.1	$	145.2	$	362.7	$	1,123.6
Operating income	124.8		56.3		54.4		107.8		343.3
Income from continuing operations	72.2		28.7		27.7		63.7		192.3
Discontinued operations, net of income taxes	78.1		68.8		—		—		146.9
Net income attributable to Questar	150.3		97.5		27.7		63.7		339.2
Per-share information attributable to Questar
Basic EPS from continuing operations	$	0.41	$	0.17	$	0.15	$	0.36	$	1.09
Basic EPS attributable to Questar	0.86		0.56		0.15		0.36		1.93
Diluted EPS from continuing operations	0.41		0.16		0.15		0.36		1.08
Diluted EPS attributable to Questar	0.85		0.55		0.15		0.36		1.91