Basis of Presentation of Interim Consolidated Financial Statements (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
REVENUES
Natural gas sales	$ 161.2	$ 312.6
Oil sales	110.8	63.0
NGL sales	97.4	47.9
Gathering, processing and other	49.8	46.6
OPERATING EXPENSES
Natural gas, oil and NGL transportation and other handling costs	33.9	21.7
Prior periods presentation of revenues
REVENUES
Natural gas sales		271.0	[1]
Oil sales		62.3	[1]
NGL sales		45.8	[1]
Gathering, processing and other		69.3	[1]
OPERATING EXPENSES
Natural gas, oil and NGL transportation and other handling costs		0	[1]
Restatement Adjustment [Member]
REVENUES
Natural gas sales		41.6
Oil sales		0.7
NGL sales		2.1
Gathering, processing and other		(22.7)
OPERATING EXPENSES
Natural gas, oil and NGL transportation and other handling costs		$ 21.7

[1] In addition to the revision described above, QEP Field Services NGL sales of $28.6 million in the first quarter of 2011 have been reclassified from "Gathering, processing and other" into "NGL sales" in the as reported column to be consistent with current period presentation. QEP reported NGL sales of $17.2 million and Gathering, processing and other of $97.9 million in its first quarter 2011 Form 10-Q. The reclassification is all within Revenues and has no effect on income from continuing operations, net income or earnings per share.