Operations by Line of Business (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues
Total Revenues	$ 696.5	$ 603.2
Operating expenses
Purchased gas, oil and NGL expense	196.8	188.4
Lease operating expense	38.9	40.1
Natural gas, oil and NGL transportation and other handling costs	34.0	34.5
Gathering, processing and other	20.6	23.7
General and administrative	46.0	36.0
Production and property taxes	35.9	24.7
Depreciation, depletion and amortization	254.2	199.3
Other operating expenses	5.1	8.5
Total Operating Expenses	631.5	555.2
Net (loss) gain from asset sales	(0.2)	1.5
Operating (loss) income	64.8	49.5
Realized and unrealized gains (losses) on derivative contracts	(34.6)	216.3
Interest and other income	2.0	1.7
Income from unconsolidated affiliates	1.3	1.9
Interest expense	(39.4)	(24.7)
Income (loss) before income taxes	(5.9)	244.7
Income taxes	2.2	(88.7)
Net (loss) income	(3.7)	156.0
Net income attributable to noncontrolling interest	(0.6)	(0.8)
Net income (loss) attributable to QEP	(4.3)	155.2
Unaffiliated customers [Member]
Revenues
Total Revenues	696.5	603.2
Affiliated customers [Member]
Revenues
Total Revenues	0	0
QEP Energy [Member]
Revenues
Total Revenues	508.2	396.8
Operating expenses
Purchased gas, oil and NGL expense	65.7	72.5
Lease operating expense	41.0	40.8
Natural gas, oil and NGL transportation and other handling costs	56.2	50.4
Gathering, processing and other	0	0
General and administrative	36.7	32.4
Production and property taxes	34.7	22.9
Depreciation, depletion and amortization	238.1	183.7
Other operating expenses	5.1	8.5
Total Operating Expenses	477.5	411.2
Net (loss) gain from asset sales	0.1	1.5
Operating (loss) income	30.8	(12.9)
Realized and unrealized gains (losses) on derivative contracts	(34.2)	207.2
Interest and other income	1.7	1.7
Income from unconsolidated affiliates	0	0
Interest expense	(45.3)	(23.6)
Income (loss) before income taxes	(47.0)	172.4
Income taxes	17.2	(64.3)
Net (loss) income	(29.8)	108.1
Net income attributable to noncontrolling interest	0	0
Net income (loss) attributable to QEP	(29.8)	108.1
QEP Energy [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	508.2	396.8
QEP Energy [Member] | Affiliated customers [Member]
Revenues
Total Revenues	0	0
QEP Field Services [Member]
Revenues
Total Revenues	92.0	119.7
Operating expenses
Purchased gas, oil and NGL expense	5.1	0
Lease operating expense	0	0
Natural gas, oil and NGL transportation and other handling costs	2.8	8.8
Gathering, processing and other	20.3	23.4
General and administrative	9.5	4.4
Production and property taxes	1.1	1.7
Depreciation, depletion and amortization	15.8	15.4
Other operating expenses	0	0
Total Operating Expenses	54.6	53.7
Net (loss) gain from asset sales	(0.3)	0
Operating (loss) income	37.1	66.0
Realized and unrealized gains (losses) on derivative contracts	0	4.1
Interest and other income	0.3	0
Income from unconsolidated affiliates	1.3	1.9
Interest expense	(4.0)	(2.3)
Income (loss) before income taxes	34.7	69.7
Income taxes	(12.5)	(23.5)
Net (loss) income	22.2	46.2
Net income attributable to noncontrolling interest	(0.6)	(0.8)
Net income (loss) attributable to QEP	21.6	45.4
QEP Field Services [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	64.4	93.6
QEP Field Services [Member] | Affiliated customers [Member]
Revenues
Total Revenues	27.6	26.1
QEP Marketing and Other [Member]
Revenues
Total Revenues	341.1	245.1
Operating expenses
Purchased gas, oil and NGL expense	342.5	247.6
Lease operating expense	0	0
Natural gas, oil and NGL transportation and other handling costs	0	0
Gathering, processing and other	0.3	0.2
General and administrative	1.0	0.6
Production and property taxes	0.1	0.1
Depreciation, depletion and amortization	0.3	0.2
Other operating expenses	0	0
Total Operating Expenses	344.2	248.7
Net (loss) gain from asset sales	0	0
Operating (loss) income	(3.1)	(3.6)
Realized and unrealized gains (losses) on derivative contracts	(0.4)	5.0
Interest and other income	51.2	25.9
Income from unconsolidated affiliates	0	0
Interest expense	(41.3)	(24.7)
Income (loss) before income taxes	6.4	2.6
Income taxes	(2.5)	(0.9)
Net (loss) income	3.9	1.7
Net income attributable to noncontrolling interest	0	0
Net income (loss) attributable to QEP	3.9	1.7
QEP Marketing and Other [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	123.9	112.8
QEP Marketing and Other [Member] | Affiliated customers [Member]
Revenues
Total Revenues	217.2	132.3
Elimination [Member]
Revenues
Total Revenues	(244.8)	(158.4)
Operating expenses
Purchased gas, oil and NGL expense	(216.5)	(131.7)
Lease operating expense	(2.1)	(0.7)
Natural gas, oil and NGL transportation and other handling costs	(25.0)	(24.7)
Gathering, processing and other	0	0.1
General and administrative	(1.2)	(1.4)
Production and property taxes	0	0
Depreciation, depletion and amortization	0	0
Other operating expenses	0	0
Total Operating Expenses	(244.8)	(158.4)
Net (loss) gain from asset sales	0	0
Operating (loss) income	0	0
Realized and unrealized gains (losses) on derivative contracts	0	0
Interest and other income	(51.2)	(25.9)
Income from unconsolidated affiliates	0	0
Interest expense	51.2	25.9
Income (loss) before income taxes	0	0
Income taxes	0	0
Net (loss) income	0	0
Net income attributable to noncontrolling interest	0	0
Net income (loss) attributable to QEP	0	0
Elimination [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	0	0
Elimination [Member] | Affiliated customers [Member]
Revenues
Total Revenues	$ (244.8)	$ (158.4)