Acquisitions & Divestitures Supplemental Proforma Results of Operations (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Business Acquisition [Line Items]
Total Revenues	$ 910.0	$ 719.5	$ 2,614.7	$ 2,064.8
Net income attributable to QEP	171.1	37.3	118.5	211.4
Earnings Per Share, Basic	$ 0.95	$ 0.21	$ 0.66	$ 1.18
Earnings Per Share, Diluted	$ 0.94	$ 0.21	$ 0.66	$ 1.18
Business Acquisition, Pro Forma Revenue		776.5	2,640.8	2,195.4
Business Acquisition, Pro Forma Net Income (Loss)		$ 54.2	$ 125.5	$ 240.4
Business Acquisition, Pro Forma Earnings Per Share, Basic		$ 0.30	$ 0.70	$ 1.34
Business Acquisition, Pro Forma Earnings Per Share, Diluted		$ 0.30	$ 0.70	$ 1.34