Debt (Details) (USD $) In Millions, unless otherwise specified	0 Months Ended	3 Months Ended
	Aug. 14, 2013	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Debt Instrument [Line Items]
Total principal amount of debt		$ 3,923.3		$ 3,001.8
Long-term debt issuance costs paid		(1.1)	0
Revolving credit facility origination fees	(3.0)
Less unamortized discount		(4.1)		(4.3)
Total long-term debt outstanding		3,919.2		2,997.5
Debt Maturity Period		5 years 0 months 0 days
Proceeds from Issuance of Long-term Debt		300.0	0
Principal amount of senior notes outstanding		2,221.8
Debt Instrument, Maturity Date Range, Start		Sep. 01, 2016
Debt Instrument, Maturity Date Range, End		May 01, 2023
Senior Notes, stated interest rate, minimum (in hundredths)		5.25%
Senior Notes, stated interest rate, maximim (in hundredths)		6.875%
Revolving Credit Facility due 2016 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		1,101.5		480.0
Maturity date of long-term debt		Aug. 25, 2016
Borrowing capacity		1,500.0
Potential increased borrowing capacity		2,000.0
Number of maturity date extentions		2
Additional period with in which maturity to be extended		1 year
Weighted-average interest rate (in hundredths)		2.19%	2.35%
Amount outstanding		1,101.5
Letters of credit outstanding		3.8
QEP Midstream's Credit Facility [Member]
Debt Instrument [Line Items]
Total principal amount of debt		0		0
Maturity date of long-term debt		Aug. 14, 2018
Borrowing capacity		500.0
Potential increased borrowing capacity		750.0
Term Loan due 2017 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		600.0		300.0
Maturity date of long-term debt		Apr. 18, 2017
Derivative Liability, Notional Amount		600.0
Additional period with in which maturity to be extended		1 year
Weighted-average interest rate (in hundredths)		1.59%	2.26%
6.05% Senior Notes due 2016 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		176.8		176.8
Long-term debt, interest rate (in hundredths)		6.05%
Maturity date of long-term debt		Sep. 01, 2016
6.80% Senior Notes due 2018 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		134.0		134.0
Long-term debt, interest rate (in hundredths)		6.80%
Maturity date of long-term debt		Apr. 01, 2018
6.80% Senior Notes due 2020 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		136.0		136.0
6.875% Senior Notes due 2021 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		625.0		625.0
5.375% Senior Notes due 2022 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		500.0		500.0
5.25% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Total principal amount of debt		$ 650.0		$ 650.0