Operations by Line of Business (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Revenues
Total Revenues	$ 751.0	$ 499.3	$ 1,447.5	$ 1,102.5
Operating expenses
Purchased gas, oil and NGL expense	207.0	124.9	403.8	313.3
Lease operating expense	43.5	40.5	82.4	80.6
Natural gas, oil and NGL transportation and other handling costs	37.3	40.7	71.3	75.2
Gathering, processing and other	23.5	20.6	44.1	44.3
General and administrative	40.9	36.8	86.9	72.8
Production and property taxes	39.3	19.4	75.2	44.1
Depreciation, depletion and amortization	249.8	214.4	504.0	413.7
Other operating expenses	2.8	57.5	7.9	66.0
Total Operating Expenses	644.1	554.8	1,275.6	1,110.0
Net (loss) gain from asset sales	100.4	0	100.2	1.5
Operating (loss) income	207.3	(55.5)	272.1	(6.0)
Realized and unrealized gains (losses) on derivative contracts	114.0	82.3	79.4	298.6
Interest and other income	3.1	0.9	5.1	2.6
Income from unconsolidated affiliates	1.6	1.4	2.9	3.3
Loss from early extinguishment of debt	0	(0.6)	0	(0.6)
Interest expense	(41.4)	(28.2)	(80.8)	(52.9)
Income (loss) before income taxes	284.6	0.3	278.7	245.0
Income taxes	(104.8)	(0.1)	(102.6)	(88.8)
Net (loss) income	179.8	0.2	176.1	156.2
Net income attributable to noncontrolling interest	(1.4)	(0.9)	(2.0)	(1.7)
Net income (loss) attributable to QEP	178.4	(0.7)	174.1	154.5
Unaffiliated customers [Member]
Revenues
Total Revenues	751.0	499.3	1,447.5	1,102.5
Affiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
QEP Energy [Member]
Revenues
Total Revenues	528.5	335.5	1,036.7	732.3
Operating expenses
Purchased gas, oil and NGL expense	54.9	40.6	120.6	113.1
Lease operating expense	45.7	41.4	86.7	82.2
Natural gas, oil and NGL transportation and other handling costs	59.5	57.2	115.7	107.6
Gathering, processing and other	0	0	0	0
General and administrative	30.0	28.7	66.7	61.1
Production and property taxes	37.6	18.2	72.3	41.1
Depreciation, depletion and amortization	238.0	198.0	476.1	381.7
Other operating expenses	2.8	57.5	7.9	66.0
Total Operating Expenses	468.5	441.6	946.0	852.8
Net (loss) gain from asset sales	100.5		100.6	1.5
Operating (loss) income	160.5	(106.1)	191.3	(119.0)
Realized and unrealized gains (losses) on derivative contracts	109.4	81.8	75.2	289.0
Interest and other income	3.2	0.7	4.9	2.4
Income from unconsolidated affiliates	0	0.1	0	0.1
Loss from early extinguishment of debt		0		0
Interest expense	(48.9)	(23.4)	(94.2)	(47.0)
Income (loss) before income taxes	224.2	(46.9)	177.2	125.5
Income taxes	(82.1)	16.6	(64.9)	(47.7)
Net (loss) income	142.1	(30.3)	112.3	77.8
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	142.1	(30.3)	112.3	77.8
QEP Energy [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	528.5	335.5	1,036.7	732.3
QEP Energy [Member] | Affiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
QEP Field Services [Member]
Revenues
Total Revenues	102.9	113.6	194.9	233.3
Operating expenses
Purchased gas, oil and NGL expense	3.5	4.1	8.6	4.1
Lease operating expense	0	0	0	0
Natural gas, oil and NGL transportation and other handling costs	5.4	12.0	8.2	20.8
Gathering, processing and other	23.0	20.4	43.3	43.8
General and administrative	10.9	8.8	20.4	13.2
Production and property taxes	1.7	1.2	2.8	2.9
Depreciation, depletion and amortization	11.7	16.3	27.5	31.7
Other operating expenses	0	0	0	0
Total Operating Expenses	56.2	62.8	110.8	116.5
Net (loss) gain from asset sales	(0.1)		(0.4)	0
Operating (loss) income	46.6	50.8	83.7	116.8
Realized and unrealized gains (losses) on derivative contracts	0	4.8	0	8.9
Interest and other income	0	0.1	0.3	0.1
Income from unconsolidated affiliates	1.6	1.3	2.9	3.2
Loss from early extinguishment of debt		0		0
Interest expense	(5.3)	(3.6)	(9.3)	(5.9)
Income (loss) before income taxes	42.9	53.4	77.6	123.1
Income taxes	(15.1)	(19.2)	(27.6)	(42.7)
Net (loss) income	27.8	34.2	50.0	80.4
Net income attributable to noncontrolling interest	(1.4)	(0.9)	(2.0)	(1.7)
Net income (loss) attributable to QEP	26.4	33.3	48.0	78.7
QEP Field Services [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	72.3	83.4	136.7	177.0
QEP Field Services [Member] | Affiliated customers [Member]
Revenues
Total Revenues	30.6	30.2	58.2	56.3
QEP Marketing and Other [Member]
Revenues
Total Revenues	371.9	198.6	713.0	443.7
Operating expenses
Purchased gas, oil and NGL expense	369.9	197.4	712.4	445.0
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	0.5	0.8	0.7
General and administrative	1.2	0.8	2.2	1.4
Production and property taxes	0	0	0.1	0.1
Depreciation, depletion and amortization	0.1	0.1	0.4	0.3
Other operating expenses	0	0	0	0
Total Operating Expenses	371.7	198.8	715.9	447.5
Net (loss) gain from asset sales	0		0	0
Operating (loss) income	0.2	(0.2)	(2.9)	(3.8)
Realized and unrealized gains (losses) on derivative contracts	4.6	(4.3)	4.2	0.7
Interest and other income	54.7	26.8	105.9	52.7
Income from unconsolidated affiliates	0	0	0	0
Loss from early extinguishment of debt		(0.6)		(0.6)
Interest expense	(42.0)	(27.9)	(83.3)	(52.6)
Income (loss) before income taxes	17.5	(6.2)	23.9	(3.6)
Income taxes	(7.6)	2.5	(10.1)	1.6
Net (loss) income	9.9	(3.7)	13.8	(2.0)
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	9.9	(3.7)	13.8	(2.0)
QEP Marketing and Other [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	150.2	80.4	274.1	193.2
QEP Marketing and Other [Member] | Affiliated customers [Member]
Revenues
Total Revenues	221.7	118.2	438.9	250.5
Elimination [Member]
Revenues
Total Revenues	(252.3)	(148.4)	(497.1)	(306.8)
Operating expenses
Purchased gas, oil and NGL expense	(221.3)	(117.2)	(437.8)	(248.9)
Lease operating expense	(2.2)	(0.9)	(4.3)	(1.6)
Natural gas, oil and NGL transportation and other handling costs	(27.6)	(28.5)	(52.6)	(53.2)
Gathering, processing and other	0	(0.3)	0	(0.2)
General and administrative	(1.2)	(1.5)	(2.4)	(2.9)
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	(252.3)	(148.4)	(497.1)	(306.8)
Net (loss) gain from asset sales	0		0	0
Operating (loss) income	0	0	0	0
Realized and unrealized gains (losses) on derivative contracts	0	0	0	0
Interest and other income	(54.8)	(26.7)	(106.0)	(52.6)
Income from unconsolidated affiliates	0	0	0	0
Loss from early extinguishment of debt		0		0
Interest expense	54.8	26.7	106.0	52.6
Income (loss) before income taxes	0	0	0	0
Income taxes	0	0	0	0
Net (loss) income	0	0	0	0
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	0	0	0	0
Elimination [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
Elimination [Member] | Affiliated customers [Member]
Revenues
Total Revenues	$ (252.3)	$ (148.4)	$ (497.1)	$ (306.8)