CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2011		Dec. 31, 2010		Dec. 31, 2009
CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME [Abstract]
Net income	$ 270.4		$ 329.1		$ 296.1
Gains (losses) on changes in unrealized fair value of derivatives designated as cash flow hedges	24.8	[1]	136.7	[1]	(254.5)	[1]
Net unamortized gain (loss) incurred	(14.7)	[2]	2.6	[2]	0	[2]
Prior service cost incurred	0	[3]	(33.8)	[3]	0	[3]
Recognized prior service cost	3.5	[4]	1.7	[4]	0	[4]
Total pension and other postretirement plans adjustments	(11.2)		(29.5)		0
Other comprehensive income	13.6		107.2		(254.5)
Comprehensive income	284.0		436.3		41.6
Comprehensive income attributable to noncontrolling interests	(3.2)		(2.9)		(2.6)
Comprehensive income attributable to QEP	$ 280.8		$ 433.4		$ 39.0

[1] Presented net of income tax expense of $14.7 million, and $81.0 million for the years ended December 31, 2011 and 2010 and net of income tax benefit of $150.6 million for the year ended December 31, 2009, respectively.

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

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

[4] Presented net of income tax expense of $2.1 million and $1.0 million for the years ended December 31, 2011 and 2010, respectively.