CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013		Mar. 31, 2012
Statement of Other Comprehensive Income [Abstract]
Net (loss) income	$ (3.7)		$ 156.0
Other comprehensive (loss) income, net of tax:
Reclassification of previously deferred derivative gains(1)	(20.1)	[1]	(47.0)	[1]
Pension and other postretirement plans adjustments:
Amortization of net actuarial loss	0.4	[2]	0.1	[2]
Amortization of prior service cost	0.8	[3]	0.9	[3]
Total pension and other postretirement plans adjustments	1.2		1.0
Other comprehensive loss	(18.9)		(46.0)
Comprehensive (loss) income	(22.6)		110.0
Comprehensive income attributable to noncontrolling interests	(0.6)		(0.8)
Comprehensive (loss) income attributable to QEP	$ (23.2)		$ 109.2

[1] Presented net of income tax benefit of $11.9 million and $27.8 million during the three months ended March 31, 2013 and 2012, respectively.

[2] Presented net of income tax expense of $0.2 million and $0.1 million during the three months ended March 31, 2013 and 2012, respectively.

[3] Presented net of income tax expense of $0.5 million and $0.5 million during the three months ended March 31, 2013 and 2012, respectively.