Acquisitions & Divestitures Supplemental Proforma Results of Operations (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Business Acquisition [Line Items]
Total Revenues	$ 936.7	$ 751.0	$ 1,820.6	$ 1,447.5
Net Income (Loss) Attributable to QEP	(92.3)	178.4	(52.6)	174.1
Earnings Per Share, Basic	$ (0.51)	$ 0.99	$ (0.29)	$ 0.97
Earnings Per Share, Diluted	$ (0.51)	$ 0.99	$ (0.29)	$ 0.97
Business Acquisition, Pro Forma Revenue		790.1	1,846.7	1,521.1
Business Acquisition, Pro Forma Net Income (Loss)		$ 182.6	$ (45.6)	$ 186.2
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 1.02	$ (0.25)	$ 1.04
Business Acquisition, Pro Forma Earnings Per Share, Diluted	$ 1.02		$ (0.25)	$ 1.04