Operations by Line of Business (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended			6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011		Jun. 30, 2012		Jun. 30, 2011
Revenues
Total Revenues	$ 499.3	$ 808.1	[1]	$ 1,102.5	[2]	$ 1,426.0	[3]
Operating expenses
Purchased gas, oil and NGL expense	124.9	303.9		313.3		450.6
Lease operating expense	40.5	34.3		80.6		67.1
Natural gas, oil and NGL transportation and other handling costs	40.7	24.0		75.2		45.7
Gathering, processing and other	20.6	27.2		44.3		52.4
General and administrative	36.8	28.7		72.8		60.4
Production and property taxes	19.4	27.1		44.1		50.8
Depreciation, depletion and amortization	214.1	186.6		413.3		377.4
Other operating expenses	57.8	7.6		66.4		15.8
Total Operating Expenses	554.8	639.4		1,110.0		1,120.2
Net loss from asset sales	0	0.2		1.5		0.2
Operating (loss) income	(55.5)	168.9	[4]	(6.0)	[5]	306.0	[6]
Realized and unrealized gains (losses) on derivative contracts	82.3	0		298.6		0
Interest and other income	0.9	(0.4)		2.6		0.2
Income from unconsolidated affiliates	1.4	1.3		3.3		2.2
Loss from early extinguishment of debt	(0.6)	0		(0.6)		0
Interest expense	(28.2)	(22.1)		(52.9)		(44.2)
Income (loss) before income taxes	0.3	147.7		245.0		264.2
Income taxes	(0.1)	(54.2)		(88.8)		(96.9)
Net income	0.2	93.5		156.2		167.3
Net income attributable to noncontrolling interest	(0.9)	(0.7)		(1.7)		(1.3)
Net income (loss) attributable to QEP	(0.7)	92.8	[7]	154.5	[8]	166.0	[9]
Unaffiliated customers [Member]
Revenues
Total Revenues	499.3	808.1	[1]	1,102.5	[2]	1,426.0	[3]
Affiliated customers [Member]
Revenues
Total Revenues	0	0	[1]	0	[2]	0	[3]
QEP Energy [Member]
Revenues
Total Revenues	335.5	555.5	[1]	732.3	[2]	951.7	[3]
Operating expenses
Purchased gas, oil and NGL expense	40.6	154.7		113.1		154.7
Lease operating expense	41.4	35.0		82.2		68.4
Natural gas, oil and NGL transportation and other handling costs	57.2	42.3		107.6		85.8
Gathering, processing and other	0	0		0		0
General and administrative	29.2	22.9		62.1		46.8
Production and property taxes	18.2	25.4		41.1		47.6
Depreciation, depletion and amortization	197.2	172.5		380.3		349.6
Other operating expenses	57.8	7.6		66.4		15.8
Total Operating Expenses	441.6	460.4		852.8		768.7
Net loss from asset sales		0.2		1.5		0.2
Operating (loss) income	(106.1)	95.3	[4]	(119.0)	[5]	183.2	[6]
Realized and unrealized gains (losses) on derivative contracts	81.8			289.0
Interest and other income	0.7	(0.5)		2.4		0.2
Income from unconsolidated affiliates	0.1	0.1		0.1		0.1
Loss from early extinguishment of debt	0			0
Interest expense	(23.4)	(20.4)		(47.0)		(40.3)
Income (loss) before income taxes	(46.9)	74.5		125.5		143.2
Income taxes	16.6	(27.7)		(47.7)		(53.3)
Net income	(30.3)	46.8		77.8		89.9
Net income attributable to noncontrolling interest	0	0		0		0
Net income (loss) attributable to QEP	(30.3)	46.8	[7]	77.8	[8]	89.9	[9]
QEP Energy [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	335.5	555.5	[1]	732.3	[2]	951.7	[3]
QEP Energy [Member] | Affiliated customers [Member]
Revenues
Total Revenues	0	0	[1]	0	[2]	0	[3]
QEP Field Services [Member]
Revenues
Total Revenues	113.6	122.2	[1]	233.3	[2]	218.8	[3]
Operating expenses
Purchased gas, oil and NGL expense	4.1	0		4.1		0
Lease operating expense	0	0		0		0
Natural gas, oil and NGL transportation and other handling costs	12.0	1.2		20.8		2.1
Gathering, processing and other	20.4	26.9		43.8		51.7
General and administrative	9.0	6.8		13.5		15.8
Production and property taxes	1.2	1.6		2.9		3.0
Depreciation, depletion and amortization	16.1	13.5		31.4		26.7
Other operating expenses	0	0		0		0
Total Operating Expenses	62.8	50.0		116.5		99.3
Net loss from asset sales		0.1		0		0.1
Operating (loss) income	50.8	72.3	[4]	116.8	[5]	119.6	[6]
Realized and unrealized gains (losses) on derivative contracts	4.8			8.9
Interest and other income	0.1	0		0.1		0
Income from unconsolidated affiliates	1.3	1.2		3.2		2.1
Loss from early extinguishment of debt	0			0
Interest expense	(3.6)	(3.1)		(5.9)		(6.6)
Income (loss) before income taxes	53.4	70.4		123.1		115.1
Income taxes	(19.2)	(25.5)		(42.7)		(41.6)
Net income	34.2	44.9		80.4		73.5
Net income attributable to noncontrolling interest	(0.9)	(0.7)		(1.7)		(1.3)
Net income (loss) attributable to QEP	33.3	44.2	[7]	78.7	[8]	72.2	[9]
QEP Field Services [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	83.4	102.0	[1]	177.0	[2]	175.3	[3]
QEP Field Services [Member] | Affiliated customers [Member]
Revenues
Total Revenues	30.2	20.2	[1]	56.3	[2]	43.5	[3]
QEP Marketing and Other [Member]
Revenues
Total Revenues	198.6	295.8	[1]	443.7	[2]	577.3	[3]
Operating expenses
Purchased gas, oil and NGL expense	197.4	292.5		445.0		570.4
Lease operating expense	0	0		0		0
Natural gas, oil and NGL transportation and other handling costs	0	0		0		0
Gathering, processing and other	0.5	0.4		0.7		0.7
General and administrative	0.1	0.8		0.1		1.6
Production and property taxes	0	0.1		0.1		0.2
Depreciation, depletion and amortization	0.8	0.6		1.6		1.1
Other operating expenses	0	0		0		0
Total Operating Expenses	198.8	294.4		447.5		574.0
Net loss from asset sales		(0.1)		0		(0.1)
Operating (loss) income	(0.2)	1.3	[4]	(3.8)	[5]	3.2	[6]
Realized and unrealized gains (losses) on derivative contracts	(4.3)			0.7
Interest and other income	26.8	24.8		52.7		49.2
Income from unconsolidated affiliates	0	0		0		0
Loss from early extinguishment of debt	(0.6)			(0.6)
Interest expense	(27.9)	(23.3)		(52.6)		(46.5)
Income (loss) before income taxes	(6.2)	2.8		(3.6)		5.9
Income taxes	2.5	(1.0)		1.6		(2.0)
Net income	(3.7)	1.8		(2.0)		3.9
Net income attributable to noncontrolling interest	0	0		0		0
Net income (loss) attributable to QEP	(3.7)	1.8	[7]	(2.0)	[8]	3.9	[9]
QEP Marketing and Other [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	80.4	150.6	[1]	193.2	[2]	299.0	[3]
QEP Marketing and Other [Member] | Affiliated customers [Member]
Revenues
Total Revenues	118.2	145.2	[1]	250.5	[2]	278.3	[3]
Elimination [Member]
Revenues
Total Revenues	(148.4)	(165.4)	[1]	(306.8)	[2]	(321.8)	[3]
Operating expenses
Purchased gas, oil and NGL expense	(117.2)	(143.3)		(248.9)		(274.5)
Lease operating expense	(0.9)	(0.7)		(1.6)		(1.3)
Natural gas, oil and NGL transportation and other handling costs	(28.5)	(19.5)		(53.2)		(42.2)
Gathering, processing and other	(0.3)	(0.1)		(0.2)		0
General and administrative	(1.5)	(1.8)		(2.9)		(3.8)
Production and property taxes	0	0		0		0
Depreciation, depletion and amortization	0	0		0		0
Other operating expenses	0	0		0		0
Total Operating Expenses	(148.4)	(165.4)		(306.8)		(321.8)
Net loss from asset sales		0		0		0
Operating (loss) income	0	0	[4]	0	[5]	0	[6]
Realized and unrealized gains (losses) on derivative contracts	0			0
Interest and other income	(26.7)	(24.7)		(52.6)		(49.2)
Income from unconsolidated affiliates	0	0		0		0
Loss from early extinguishment of debt	0			0
Interest expense	26.7	24.7		52.6		49.2
Income (loss) before income taxes	0	0		0		0
Income taxes	0	0		0		0
Net income	0	0		0		0
Net income attributable to noncontrolling interest	0	0		0		0
Net income (loss) attributable to QEP	0	0	[7]	0	[8]	0	[9]
Elimination [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	0	0	[1]	0	[2]	0	[3]
Elimination [Member] | Affiliated customers [Member]
Revenues
Total Revenues	$ (148.4)	$ (165.4)	[1]	$ (306.8)	[2]	$ (321.8)	[3]

[1] Revenues for the three months ended June 30, 2011, have been recast to reflect QEP’s revised reporting of its transportation and handling costs. See Note 2 - Basis of Presentation of Interim Consolidated Financial Statements for additional information. In addition, revenues for the three months ended June 30, 2011, reflect the impact of QEP’s settled derivative contracts. See Note 6 - Derivative Contracts for detailed information on derivative contract settlements in the three months ended June 30, 2011.

[2] The impact of QEP’s settled derivative contracts, for the six months ended June 30, 2012, are reflected below operating (loss) income.

[3] Revenues for the six months ended June 30, 2011, have been recast to reflect QEP’s revised reporting of its transportation and handling costs. See Note 2 - Basis of Presentation of Interim Consolidated Financial Statements for additional information. In addition, revenues for the six months ended June 30, 2011, reflect the impact of QEP’s settled derivative contracts. See Note 6 - Derivative Contracts for detailed information on derivative contract settlements in the six months ended June 30, 2011.

[4] Under hedge accounting, gains and losses from realized commodity derivative contract settlements were included in revenues and operating income during the three months ended June 30, 2011.

[5] Operating (loss) income for the six months ended June 30, 2012, excludes the impact of realized commodity derivative contract settlements. During the six months ended June 30, 2012, gains and losses from realized commodity derivative contract settlements were included below operating (loss) income.

[6] Under hedge accounting, realized gains and losses from realized commodity derivative contract settlements were included in revenues and operating income during the three and six months ended June 30, 2011.

[7] Under hedge accounting, unrealized gains and losses from changes in the fair value were deferred in accumulated other comprehensive income during the three months ended June 30, 2011.

[8] Net (loss) income attributable to QEP for the six months ended June 30, 2012, includes the impact of unrealized gains and losses from changes in the fair value of the commodity derivative contracts.

[9] Under hedge accounting, unrealized gains and losses from changes in the fair value were deferred in accumulated other comprehensive income during the three and six months ended June 30, 2011.