Operations by Line of Business (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013	Dec. 31, 2013
Segment Reporting Information [Line Items]
Noncontrolling Interest, Ownership Percentage by Parent	57.80%		57.80%
Revenues
Total Revenues	$ 936.7	$ 751.0	$ 1,820.6	$ 1,447.5
Operating expenses
Purchased gas, oil and NGL expense	235.7	207.0	460.0	403.8
Lease operating expense	57.5	43.5	112.8	82.4
Natural gas, oil and NGL transportation and other handling costs	54.3	37.3	97.7	71.3
Gathering, processing and other	24.8	23.5	50.6	44.1
General and administrative	64.2	40.9	120.8	86.9
Production and property taxes	56.1	39.3	105.4	75.2
Depreciation, depletion and amortization	249.7	249.8	489.9	504.0
Other operating expenses	3.2	2.8	7.4	7.9
Total Operating Expenses	745.5	644.1	1,444.6	1,275.6
Net (loss) gain from asset sales	(201.0)	100.4	(198.6)	100.2
Operating (loss) income	(9.8)	207.3	177.4	272.1
Realized and unrealized gains (losses) on derivative contracts	(88.0)	114.0	(168.9)	79.4
Interest and other income	0.8	3.1	3.7	5.1
Income from unconsolidated affiliates	1.2	1.6	3.4	2.9
Interest expense	(45.7)	(41.4)	(88.2)	(80.8)
Income (loss) before income taxes	(141.5)	284.6	(72.6)	278.7
Income taxes	54.2	(104.8)	30.8	(102.6)
Net income (loss)	(87.3)	179.8	(41.8)	176.1
Net income attributable to noncontrolling interest	(5.0)	(1.4)	(10.8)	(2.0)
Net income (loss) attributable to QEP	(92.3)	178.4	(52.6)	174.1
Assets	10,562.8	9,447.1	10,562.8	9,447.1	9,376.8
Unaffiliated customers [Member]
Revenues
Total Revenues	936.7	751.0	1,820.6	1,447.5
Affiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
QEP Energy [Member]
Revenues
Total Revenues	687.2	528.5	1,300.4	1,036.7
Operating expenses
Purchased gas, oil and NGL expense	50.1	54.9	88.1	120.6
Lease operating expense	59.5	45.7	115.9	86.7
Natural gas, oil and NGL transportation and other handling costs	72.1	59.5	136.6	115.7
Gathering, processing and other	0	0	0	0
General and administrative	45.9	30.0	87.7	66.7
Production and property taxes	53.1	37.6	100.5	72.3
Depreciation, depletion and amortization	232.3	238.0	455.7	476.1
Other operating expenses	3.2	2.8	7.4	7.9
Total Operating Expenses	516.2	468.5	991.9	946.0
Net (loss) gain from asset sales	(200.8)	100.5	(198.4)	100.6
Operating (loss) income	(29.8)	160.5	110.1	191.3
Realized and unrealized gains (losses) on derivative contracts	(85.3)	109.4	(163.8)	75.2
Interest and other income	0.6	3.2	3.5	4.9
Income from unconsolidated affiliates	0.1	0	0.1	0
Interest expense	(56.6)	(48.9)	(105.5)	(94.2)
Income (loss) before income taxes	(171.0)	224.2	(155.6)	177.2
Income taxes	64.0	(82.1)	58.1	(64.9)
Net income (loss)	(107.0)	142.1	(97.5)	112.3
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	(107.0)	142.1	(97.5)	112.3
Assets	9,481.7	7,984.2	9,481.7	7,984.2
QEP Energy [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	687.2	528.5	1,300.4	1,036.7
QEP Energy [Member] | Affiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
QEP Field Services [Member]
Revenues
Total Revenues	93.4	102.9	199.6	194.9
Operating expenses
Purchased gas, oil and NGL expense	1.9	3.5	1.9	8.6
Lease operating expense	0	0	0	0
Natural gas, oil and NGL transportation and other handling costs	8.8	5.4	12.4	8.2
Gathering, processing and other	24.0	23.0	49.7	43.3
General and administrative	18.7	10.9	33.1	20.4
Production and property taxes	2.9	1.7	4.7	2.8
Depreciation, depletion and amortization	16.8	11.7	33.3	27.5
Other operating expenses	0	0	0	0
Total Operating Expenses	73.1	56.2	135.1	110.8
Net (loss) gain from asset sales	(0.2)	(0.1)	(0.2)	(0.4)
Operating (loss) income	20.1	46.6	64.3	83.7
Realized and unrealized gains (losses) on derivative contracts	0	0	0	0
Interest and other income	0	0	0	0.3
Income from unconsolidated affiliates	1.1	1.6	3.3	2.9
Interest expense	(0.7)	(5.3)	(1.3)	(9.3)
Income (loss) before income taxes	20.5	42.9	66.3	77.6
Income taxes	(7.1)	(15.1)	(21.7)	(27.6)
Net income (loss)	13.4	27.8	44.6	50.0
Net income attributable to noncontrolling interest	(5.0)	(1.4)	(10.8)	(2.0)
Net income (loss) attributable to QEP	8.4	26.4	33.8	48.0
Assets	1,529.2	1,704.4	1,529.2	1,704.4
QEP Field Services [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	63.1	72.3	142.9	136.7
QEP Field Services [Member] | Affiliated customers [Member]
Revenues
Total Revenues	30.3	30.6	56.7	58.2
QEP Marketing and Other [Member]
Revenues
Total Revenues	607.0	371.9	1,110.0	713.0
Operating expenses
Purchased gas, oil and NGL expense	605.4	369.9	1,103.3	712.4
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	0.5	0.9	0.8
General and administrative	0.5	1.2	1.7	2.2
Production and property taxes	0.1	0	0.2	0.1
Depreciation, depletion and amortization	0.6	0.1	0.9	0.4
Other operating expenses	0	0	0	0
Total Operating Expenses	607.1	371.7	1,107.0	715.9
Net (loss) gain from asset sales	0	0	0	0
Operating (loss) income	(0.1)	0.2	3.0	(2.9)
Realized and unrealized gains (losses) on derivative contracts	(2.7)	4.6	(5.1)	4.2
Interest and other income	56.6	54.7	105.4	105.9
Income from unconsolidated affiliates	0	0	0	0
Interest expense	(44.8)	(42.0)	(86.6)	(83.3)
Income (loss) before income taxes	9.0	17.5	16.7	23.9
Income taxes	(2.7)	(7.6)	(5.6)	(10.1)
Net income (loss)	6.3	9.9	11.1	13.8
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	6.3	9.9	11.1	13.8
Assets	564.1	253.3	564.1	253.3
QEP Marketing and Other [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	186.4	150.2	377.3	274.1
QEP Marketing and Other [Member] | Affiliated customers [Member]
Revenues
Total Revenues	420.6	221.7	732.7	438.9
Elimination [Member]
Revenues
Total Revenues	(450.9)	(252.3)	(789.4)	(497.1)
Operating expenses
Purchased gas, oil and NGL expense	(421.7)	(221.3)	(733.3)	(437.8)
Lease operating expense	(2.0)	(2.2)	(3.1)	(4.3)
Natural gas, oil and NGL transportation and other handling costs	(26.6)	(27.6)	(51.3)	(52.6)
Gathering, processing and other	0.3	0	0	0
General and administrative	(0.9)	(1.2)	(1.7)	(2.4)
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	(450.9)	(252.3)	(789.4)	(497.1)
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	(56.4)	(54.8)	(105.2)	(106.0)
Income from unconsolidated affiliates	0	0		0
Interest expense	56.4	54.8	105.2	106.0
Income (loss) before income taxes	0	0	0	0
Income taxes	0	0	0	0
Net income (loss)	0	0	0	0
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	0	0	0	0
Assets	(1,012.2)	(494.8)	(1,012.2)	(494.8)
Elimination [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
Elimination [Member] | Affiliated customers [Member]
Revenues
Total Revenues	$ (450.9)	$ (252.3)	$ (789.4)	$ (497.1)