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Acquisitions and Divestitures Schedule of Pro Forma Results Of Operations (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended								12 Months Ended
	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Business Acquisition [Line Items]
Revenues	$ 799.6us-gaap_OilAndGasRevenue	$ 910.0us-gaap_OilAndGasRevenue	$ 887.2us-gaap_OilAndGasRevenue	$ 817.5us-gaap_OilAndGasRevenue	$ 620.3us-gaap_OilAndGasRevenue	$ 719.5us-gaap_OilAndGasRevenue	$ 694.0us-gaap_OilAndGasRevenue	$ 651.3us-gaap_OilAndGasRevenue	$ 3,414.3us-gaap_OilAndGasRevenue	$ 2,685.1us-gaap_OilAndGasRevenue	$ 2,071.7us-gaap_OilAndGasRevenue
Net income attributable to QEP	665.9us-gaap_NetIncomeLoss	171.1us-gaap_NetIncomeLoss	(92.3)us-gaap_NetIncomeLoss	39.7us-gaap_NetIncomeLoss	(52.0)us-gaap_NetIncomeLoss	37.3us-gaap_NetIncomeLoss	178.4us-gaap_NetIncomeLoss	(4.3)us-gaap_NetIncomeLoss	784.4us-gaap_NetIncomeLoss	159.4us-gaap_NetIncomeLoss	128.3us-gaap_NetIncomeLoss
Earnings Per Share, Basic									$ 4.36us-gaap_EarningsPerShareBasic	$ 0.89us-gaap_EarningsPerShareBasic	$ 0.72us-gaap_EarningsPerShareBasic
Diluted total									$ 4.36us-gaap_EarningsPerShareDiluted	$ 0.89us-gaap_EarningsPerShareDiluted	$ 0.72us-gaap_EarningsPerShareDiluted
Williston Basin Acquisition [Member]
Business Acquisition [Line Items]
Revenues											2,071.7
Net income attributable to QEP											128.3
Earnings Per Share, Basic											$ 0.72
Diluted total											$ 0.72
Business Acquisition, Pro Forma Revenue											2,207.2
Business Acquisition, Pro Forma Net Income (Loss)											143.0
Business Acquisition, Pro Forma Earnings Per Share, Basic											$ 0.80
Business Acquisition, Pro Forma Earnings Per Share, Diluted											$ 0.80
Permian Basin Acquisition [Member]
Business Acquisition [Line Items]
Revenues									3,414.3	2,685.1
Net income attributable to QEP									784.4	159.4
Earnings Per Share, Basic									$ 4.36	$ 0.89
Diluted total									$ 4.36	$ 0.89
Business Acquisition, Pro Forma Revenue									3,440.4	2,858.8
Business Acquisition, Pro Forma Net Income (Loss)									$ 791.4	$ 195.3
Business Acquisition, Pro Forma Earnings Per Share, Basic									$ 4.40	$ 1.09
Business Acquisition, Pro Forma Earnings Per Share, Diluted									$ 4.40	$ 1.09