Debt Schedule of Debt Instruments (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 3,914.8	$ 3,001.8
Less unamortized discount	(4.0)	(4.3)
Long-term Debt	3,910.8	2,997.5
Line of Credit [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	1,093.0	480.0
QEP Midstream's Credit Facility [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	0	0
Term Loan due 2017 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	600.0	300.0
Senior Notes Due 2016 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	176.8	176.8
Senior Notes Due 2018 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	134.0	134.0
Senior Notes Due 2020 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	136.0	136.0
Senior Notes Due 2021 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	625.0	625.0
Senior Notes Due 2022 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	500.0	500.0
5.25% Senior Notes Due 2023 [Member]
Debt Instrument [Line Items]
Long-term Debt, Gross	$ 650.0	$ 650.0