Derivative Contracts (Details) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Derivatives, Fair Value [Line Items]
Forecasted production from proved reserves (in hundredths)	100.00%
Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, Net of Tax	$ (77.6)	[1]	$ (171.1)	[1]	$ 24.8	[1]
Unrealized gains on derivative contracts					395.9
Unrealized gains on derivative contracts, net of tax					248.6
Asset Retirement Obligation
Total principal amount of debt	3,001.8		3,211.8
Index	NYMEX
Derivative Contracts - Volumes and Prices
Notional amount of interest rate derivatives	300.0
Fair Value of Derivative Contracts, Gross [Abstract]
Derivative Asset, Fair Value, Gross	6.5		193.9
Derivative Liability, Fair Value, Gross	32.0		7.3
Derivative instruments - long-term
Derivative instruments - short-term
Derivative instruments - long-term	0		3.6
Commodity Contract [Member] | Oil Sales (Bbls) [Member] | Year 2015 [Member] [Domain] | NYMEX WTI [Member]
Derivatives, Fair Value [Line Items]
Year	2015
Index	NYMEX WTI
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	700,000
Average Swap price per unit ($ per unit)	88.60
Swap [Member] | Natural Gas Sales (MMbtu) [Member] | Year 2015 [Member] [Domain] | NYMEX [Member]
Derivatives, Fair Value [Line Items]
Year	2015
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	3,700,000
Average Swap price per unit ($ per unit)	4.16
Swap [Member] | Natural Gas Sales (MMbtu) [Member] | 2014 [Member] | NYMEX [Member]
Derivatives, Fair Value [Line Items]
Year	2014
Index	NYMEX
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	25,600,000
Average Swap price per unit ($ per unit)	4.19
Swap [Member] | Natural Gas Sales (MMbtu) [Member] | 2014 [Member] | IFNPCR [Member]
Derivatives, Fair Value [Line Items]
Year	2014
Index	IFNPCR
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	58,400,000
Average Swap price per unit ($ per unit)	3.98
Swap [Member] | Oil Sales (Bbls) [Member] | NYMEX WTI [Member]
Derivatives, Fair Value [Line Items]
Year	2014
Index	ICE Brent
Derivative Contracts - Volumes and Prices
Average Swap price per unit ($ per unit)	13.78
Swap [Member] | Oil Sales (Bbls) [Member] | NYMEX WTI [Member]
Derivatives, Fair Value [Line Items]
Year	2014
Index	NYMEX WTI
Derivative Contracts - Volumes and Prices
Average Swap price per unit ($ per unit)	93.68
Swap [Member] | Oil Sales (Bbls) [Member] | 2014 [Member] | NYMEX WTI [Member]
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	2,000
Swap [Member] | Oil Sales (Bbls) [Member] | 2014 [Member] | NYMEX WTI [Member]
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	12,100,000
Swap [Member] | QEP Marketing [Member] | Year 2013 [Member] | IFNPCR [Member]
Derivatives, Fair Value [Line Items]
Year	2014
Index	IFNPCR
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	4,700,000
Average Swap price per unit ($ per unit)	3.77
Swap [Member] | QEP Resources [Member]
Derivative Contracts - Volumes and Prices
Notional amount of interest rate derivatives	300.0
Maturity	Mar. 31, 2017
Fixed Rate Paid (in hundredths)	1.07%
Variable Rate Received	One month LIBOR
Swap [Member] | Purchased Gas and Oil Expense [Member] | Year 2013 [Member] | IFNPCR [Member]
Derivatives, Fair Value [Line Items]
Year	2014
Index	IFNPCR
Derivative Contracts - Volumes and Prices
Total Volume (in Bcf, Mbbl, millions of gallons, millions of MMBtu)	1,000,000
Average Swap price per unit ($ per unit)	3.78
Term Loan due 2017 [Member]
Derivatives, Fair Value [Line Items]
Total principal amount of debt	300.0		300.0
Short term [Member] | Interest Rate Swap [Member]
Fair Value of Derivative Contracts, Gross [Abstract]
Derivative Asset, Fair Value, Gross	0		0
Derivative Liability, Fair Value, Gross	2.6		2.6
Short term [Member] | Commodity Contract [Member]
Fair Value of Derivative Contracts, Gross [Abstract]
Derivative Asset, Fair Value, Gross	5.5		189.7
Derivative Liability, Fair Value, Gross	29.4		1.0
Long term [Member] | Interest Rate Swap [Member]
Fair Value of Derivative Contracts, Gross [Abstract]
Derivative Asset, Fair Value, Gross	0.6		0
Derivative Liability, Fair Value, Gross	0		3.6
Long term [Member] | Commodity Contract [Member]
Fair Value of Derivative Contracts, Gross [Abstract]
Derivative Asset, Fair Value, Gross	0.4		4.2
Derivative Liability, Fair Value, Gross	$ 0		$ 0.1

[1] Presented net of income tax benefit of $45.9 million and $101.3 million during the years ended December 31, 2013 and 2012, respectively, and net of income tax expense of $14.7 million during the year ended December 31, 2011.