CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2013		Sep. 30, 2012		Sep. 30, 2013		Sep. 30, 2012
Statement of Other Comprehensive Income [Abstract]
Net (loss) income	$ 41.1		$ (2.1)		$ 217.2		$ 154.1
Other comprehensive (loss) income, net of tax:
Reclassification of previously deferred derivative gains(1)	(19.7)	[1]	(42.1)	[1]	(60.4)	[1]	(133.8)	[1]
Pension and other postretirement plans adjustments:
Amortization of net actuarial loss	0.4	[2]	0.5	[2]	1.1	[2]	0.7	[2]
Amortization of prior service cost	0.8	[3]	0.9	[3]	2.5	[3]	2.6	[3]
Total pension and other postretirement plans adjustments	1.2		1.4		3.6		3.3
Other comprehensive loss	(18.5)		(40.7)		(56.8)		(130.5)
Comprehensive (loss) income	22.6		(42.8)		160.4		23.6
Comprehensive income attributable to noncontrolling interests	(3.8)		(1.0)		(5.8)		(2.7)
Comprehensive (loss) income attributable to QEP	$ 18.8		$ (43.8)		$ 154.6		$ 20.9

[1] Presented net of income tax benefit of $11.7 million and $35.8 million during the three and nine months ended September 30, 2013 and $24.9 million and $79.2 million during the three and nine months ended September 30, 2012, respectively.

[2] Presented net of income tax expense of $0.2 million and $0.7 million during the three and nine months ended September 30, 2013 and $0.2 million and $0.4 million during the three and nine months ended September 30, 2012, respectively.

[3] Presented net of income tax expense of $0.5 million and $1.5 million and during the three and nine months ended September 30, 2013 and $0.5 million and $1.6 million during the three and nine months ended September 30, 2012, respectively.