CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
Statement of Other Comprehensive Income [Abstract]
NET INCOME	$ 132.0		$ 270.4		$ 329.1
Other comprehensive (loss) income, net of tax:
Effect of derivative financial instruments	(171.1)	[1]	24.8	[1]	136.7	[1]
Pension and other postretirement plans adjustments:
Current year net actuarial gain (loss)	(10.0)	[2]	(14.7)	[2]	2.6	[2]
Amortization of net actuarial loss	1.1	[3]	0	[3]	0	[3]
Net prior service cost inccured	0	[4]	0	[4]	(33.8)	[4]
Amortization of net prior service cost	3.5	[5]	3.5	[5]	1.7	[5]
Net curtailment cost incurred	1.4	[6]	0	[6]	0	[6]
Total pension and other postretirement plans adjustments	(4.0)		(11.2)		(29.5)
Other comprehensive (loss) income	(175.1)		13.6		107.2
Comprehensive (loss) income	(43.1)		284.0		436.3
Comprehensive income attributable to noncontrolling interests	(3.7)		(3.2)		(2.9)
Comprehensive (loss) income attributable to QEP	$ (46.8)		$ 280.8		$ 433.4

[1] Presented net of income tax benefit of $101.3 million during the year ended December 31, 2012, and net of income tax expense of $14.7 million and $81.0 million during the years ended December 31, 2011 and 2010, respectively.

[2] Presented net of income tax benefit of $6.3 million and $9.2 million during the years ended December 31, 2012 and 2011, respectively, and net of income tax expense of $1.6 million for the year ended December 31, 2010.

[3] Presented net of income tax expense of $0.9 million during the year ended December 31, 2012.

[4] Presented net of income tax benefit of $20.9 million during the year ended December 31, 2010.

[5] Presented net of income tax expense of $2.2 million, $2.1 million and $1.0 million during the years ended December 31, 2012, 2011 and 2010, respectively.

[6] Presented net of income tax expense of $0.8 million during the year ended December 31, 2012.