Quarterly Financial Information (Unaudited) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended																12 Months Ended
	Dec. 31, 2011		Sep. 30, 2011		Jun. 30, 2011		Mar. 31, 2011		Dec. 31, 2010		Sep. 30, 2010		Jun. 30, 2010		Mar. 31, 2010		Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
Revenues	$ 853.3	[1]	$ 879.9	[1]	$ 808.1	[1]	$ 617.9	[1]	$ 587.9	[1]	$ 578.3	[1]	$ 542.3	[1]	$ 592.1	[1]	$ 3,159.2	[1]	$ 2,300.6	[1]	$ 2,011.2
Operating income	16.5		183.4		168.9		137.1		125.5		149.3		127.6		142.9		505.9		545.3		585.5
Income from continuing operations	0.7		102.4		93.5		73.8		65.8		71.9		69.5		78.7		270.4		285.9		215.4
Discontinued operations, net of income tax									0		0		22.0		21.2		0		43.2		80.7
Net income (loss) attributable to QEP	(0.3)		101.5		92.8		73.2		65.0		71.1		90.8		99.3		267.2		326.2		293.5
Per share information attributable to QEP
Basic EPS from continuing operations									$ 0.37		$ 0.40		$ 0.39		$ 0.45		$ 1.51		$ 1.61		$ 1.23
Basic EPS attributable to QEP	$ (0.01)		$ 0.58		$ 0.52		$ 0.42		$ 0.37		$ 0.40		$ 0.52		$ 0.57		$ 1.51		$ 1.86		$ 1.69
Diluted EPS from continuing operations									$ 0.37		$ 0.40		$ 0.39		$ 0.44		$ 1.50		$ 1.60		$ 1.21
Diluted EPS attributable to QEP	$ 0		$ 0.57		$ 0.52		$ 0.41		$ 0.37		$ 0.40		$ 0.51		$ 0.56		$ 1.50		$ 1.84		$ 1.67
Prior periods presentation of revenues
Revenues			$ 852.4		$ 784.1		$ 596.2		$ 572.0		$ 564.6		$ 529.6		$ 580.2				$ 2,246.4

[1] During the year ended December 31, 2011, QEP revised its reporting of transportation and handling costs which have been recast on the Consolidated Income Statement from revenues to "Natural gas, oil and NGL transportation and other handling costs" for all periods presented. See Note 1, "Summary of Significant Accounting Policies" for additional information. The following table presents prior periods presentation of revenues as previously disclosed: First Quarter Second Quarter Third Quarter Fourth Quarter Year 2011 $ 596.2 $ 784.1 $ 852.4 n/a n/a 2010 580.2 529.6 564.6 572.0 2,246.4