Discontinued Operations - Income Statement Impact of Discontinued Operations (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended				9 Months Ended
	Sep. 30, 2014		Sep. 30, 2013		Sep. 30, 2014		Sep. 30, 2013
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NGL sales	$ 51.1		$ 47.7		$ 179.3		$ 144.4
Other revenue	3.4		2.8		5.1		8.7
Purchased gas, oil and NGL sales	290.4		220.4		780.1		644.9
Total Revenues	910.0		719.5		2,614.7		2,064.8
Purchased gas, oil and NGL expense	288.4		219.5		775.5		650.3
Lease operating expense	61.1		43.5		177.0		130.2
Natural gas, oil and NGL transportation and other handling costs	71.1		58.6		198.5		158.5
Gathering, processing and other	1.4		2.1		4.8		6.4
General and administrative	49.4		40.7		147.0		116.8
Production and property taxes	59.4		40.6		160.8		113.7
Depreciation, depletion and amortization	251.4		238.4		712.5		719.3
Total operating expenses	783.1		649.0		2,184.4		1,908.7
Net loss from asset sales	(11.8)		12.8		(210.3)		113.4
OPERATING INCOME	115.1		83.3		220.0		269.5
Interest income and other loss	4.2		6.1		7.8		22.7
Income from unconsolidated affiliates					4.6		3.7
Interest expense	(41.5)		(41.4)		(128.4)		(124.7)
Net income attributable to noncontrolling interest					(17.6)		(5.8)
DISCONTINUED OPERATIONS, NET OF INCOME TAX	17.4		25.2		58.2		74.8
Income from discontinued operations before income taxes attributable to QEP from QEP Midstream	7.9		7.9		20.4		26.2
Ownership percentage	57.80%				57.80%
Midstream Business Held For Sale [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
NGL sales	28.8		23.6		94.6		70.6
Other revenue	43.1		44.2		119.9		126.4
Purchased gas, oil and NGL sales	(11.9)	[1]	(14.4)	[1]	(38.5)	[1]	(41.5)	[1]
Total Revenues	60.0		53.4		176.0		155.5
Purchased gas, oil and NGL expense	(12.4)	[1]	(14.4)	[1]	(39.5)	[1]	(41.4)	[1]
Lease operating expense	(1.7)	[1]	(0.8)	[1]	(4.8)	[1]	(2.6)	[1]
Natural gas, oil and NGL transportation and other handling costs	(10.6)	[1]	(21.7)	[1]	(40.1)	[1]	(53.0)	[1]
Gathering, processing and other	22.7		20.3		69.8		60.1
General and administrative	11.1		8.6		34.3		19.4
Production and property taxes	2.1		1.8		6.1		4.0
Depreciation, depletion and amortization	14.3		14.7		43.1		37.8
Total operating expenses	25.5		8.5		68.9		24.3
Net loss from asset sales	0		(0.1)		(0.1)		(0.5)
OPERATING INCOME	34.5		44.8		107.0		130.7
Interest income and other loss	0		(2.1)		0		(13.7)
Income from unconsolidated affiliates	1.1		0.8		4.4		3.7
Interest expense	(1.5)		(0.3)		(2.8)		2.3
INCOME FROM DISCONTINUED OPERATIONS BEFORE INCOME TAXES	34.1	[2]	43.2	[2]	108.6	[2]	123.0	[2]
Income taxes	(9.9)		(14.2)		(32.8)		(42.4)
NET INCOME FROM DISCONTINUED OPERATIONS	24.2		29.0		75.8		80.6
Net income attributable to noncontrolling interest	$ (6.8)		$ (3.8)		$ (17.6)		$ (5.8)

[1] Includes discontinued intercompany eliminations

[2] Includes income from discontinued operations before income taxes attributable to QEP from QEP Midstream (of which QEP owns 57.8%) of $7.9 million and $20.4 million for the three and nine months ended September 30, 2014, respectively, and $7.9 million and $26.2 million for the three and nine months ended September 30, 2013, respectively