Operations by Line of Business (Details) - Operating Activities [Domain] - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Operating expenses
Net income (loss)	$ (76.3)	$ (92.3)	$ (131.9)	$ (52.6)
Income from unconsolidated affiliates			0.0	3.4
Unaffiliated customers [Member]
Revenues
Total Revenues	608.6	887.2	1,100.2	1,704.7
Affiliated customers [Member]
Revenues
Total Revenues	0.0	0.0	0.0	0.0
QEP Energy [Member]
Revenues
Total Revenues	407.9	687.2	761.2	1,300.4
Operating expenses
Purchased gas and oil expense	16.8	50.1	48.0	88.1
Lease operating expense	57.1	59.5	118.9	115.9
Natural gas, oil and NGL transportation and other handling costs	75.5	72.1	142.9	136.6
Gathering, processing and other	0.0	0.0	0.0	0.0
General and administrative	50.0	52.5	96.2	97.5
Production and property taxes	31.2	53.1	58.7	100.5
Depreciation, depletion and amortization	213.2	232.3	405.9	455.7
Other operating expenses	1.3	3.2	22.4	7.4
Total operating expenses	445.1	522.8	893.0	1,001.7
Net gain (loss) from asset sales	26.5	(200.8)	(1.3)	(198.4)
Operating income (loss)	(10.7)	(36.4)	(133.1)	100.3
Realized and unrealized gains (losses) on derivative contracts	(65.6)	(85.3)	14.6	(163.8)
Interest and other income (expense)	3.1	0.6	(0.4)	3.5
Interest expense	(52.6)	56.6	(99.8)	(105.5)
Income (loss) before income taxes	(125.8)	(177.6)	(218.7)	(165.4)
Income taxes	(42.4)	67.2	76.0	60.1
Income from continuing operations		(110.4)		(105.3)
Net income (loss)	(83.4)	(110.4)	(142.7)	(105.3)
Income from unconsolidated affiliates		0.1		0.1
QEP Energy [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	407.9	687.2	761.2	1,300.4
QEP Energy [Member] | Affiliated customers [Member]
Revenues
Total Revenues	0.0	0.0	0.0	0.0
QEP Marketing and Other [Member]
Revenues
Total Revenues	448.8	611.6	794.6	1,119.4
Operating expenses
Purchased gas and oil expense	445.4	605.4	788.2	1,103.3
Lease operating expense	0.0	0.0	0.0	0.0
Natural gas, oil and NGL transportation and other handling costs	0.0	0.0	0.0	0.0
Gathering, processing and other	1.4	1.8	3.1	3.4
General and administrative	1.9	0.5	3.7	1.7
Production and property taxes	1.5	0.4	1.8	0.9
Depreciation, depletion and amortization	2.6	2.9	5.3	5.4
Other operating expenses	0.0	0.0	0.0	0.0
Total operating expenses	452.8	611.0	802.1	1,114.7
Net gain (loss) from asset sales	(2.0)	(0.1)	(4.7)	(0.1)
Operating income (loss)	(6.0)	0.5	(12.2)	4.6
Realized and unrealized gains (losses) on derivative contracts	(0.4)	(2.7)	0.3	(5.1)
Interest and other income (expense)	53.1	56.7	101.1	105.5
Interest expense	(36.0)	(44.9)	(72.7)	(86.7)
Income (loss) before income taxes	10.7	9.6	16.5	18.3
Income taxes	3.6	5.3	(5.7)	(6.4)
Income from continuing operations		4.3		11.9
Net income (loss)	7.1	4.3	10.8	11.9
Income from unconsolidated affiliates		0.0		0.0
QEP Marketing and Other [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	200.7	200.0	339.0	404.3
QEP Marketing and Other [Member] | Affiliated customers [Member]
Revenues
Total Revenues	248.1	411.6	455.6	715.1
Elimination [Member]
Revenues
Total Revenues	(248.1)	(411.6)	(455.6)	(715.1)
Operating expenses
Purchased gas and oil expense	(245.0)	(406.3)	(449.6)	(704.3)
Lease operating expense	0.0	0.0	0.0	0.0
Natural gas, oil and NGL transportation and other handling costs	(2.5)	(4.6)	(4.8)	(9.2)
Gathering, processing and other	0.0	0.0	0.0	0.0
General and administrative	(0.6)	(0.7)	(1.2)	(1.6)
Production and property taxes	0.0	0.0	0.0	0.0
Depreciation, depletion and amortization	0.0	0.0	0.0	0.0
Other operating expenses	0.0	0.0	0.0	0.0
Total operating expenses	(248.1)	(411.6)	(455.6)	(715.1)
Net gain (loss) from asset sales	0.0	0.0	0.0	0.0
Operating income (loss)	0.0	0.0	0.0	0.0
Realized and unrealized gains (losses) on derivative contracts	0.0	0.0	0.0	0.0
Interest and other income (expense)	(52.4)	(56.5)	(99.5)	(105.3)
Interest expense	52.4	(56.5)	99.5	105.3
Income (loss) before income taxes	0.0	0.0	0.0	0.0
Income taxes	0.0	0.0	0.0	0.0
Income from continuing operations		0.0		0.0
Net income (loss)	0.0	0.0	0.0	0.0
Income from unconsolidated affiliates		0.0		0.0
Elimination [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	0.0	0.0	0.0	0.0
Elimination [Member] | Affiliated customers [Member]
Revenues
Total Revenues	(248.1)	(411.6)	(455.6)	(715.1)
Discontinued Operations [Member]
Revenues
Total Revenues		0.0		0.0
Operating expenses
Purchased gas and oil expense		0.0		0.0
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		0.0		0.0
General and administrative		0.0		0.0
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		0.0		0.0
Net gain (loss) from asset sales		0.0		0.0
Operating income (loss)		0.0		0.0
Realized and unrealized gains (losses) on derivative contracts		0.0		0.0
Interest and other income (expense)		0.0		0.0
Interest expense		0.0		0.0
Income (loss) before income taxes		0.0		0.0
Income taxes		0.0		0.0
Income from continuing operations		0.0		0.0
NET INCOME (LOSS)		13.8		40.8
Net income (loss)		13.8		40.8
Income from unconsolidated affiliates		0.0		0.0
Discontinued Operations [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues		0.0		0.0
Discontinued Operations [Member] | Affiliated customers [Member]
Revenues
Total Revenues		0.0		0.0
Continuing Operations [Member]
Revenues
Total Revenues	608.6	887.2	1,100.2	1,704.7
Operating expenses
Purchased gas and oil expense	217.2	249.2	386.6	487.1
Lease operating expense	57.1	59.5	118.9	115.9
Natural gas, oil and NGL transportation and other handling costs	73.0	67.5	138.1	127.4
Gathering, processing and other	1.4	1.8	3.1	3.4
General and administrative	51.3	52.3	98.7	97.6
Production and property taxes	32.7	53.5	60.5	101.4
Depreciation, depletion and amortization	215.8	235.2	411.2	461.1
Other operating expenses	1.3	3.2	22.4	7.4
Total operating expenses	649.8	722.2	1,239.5	1,401.3
Net gain (loss) from asset sales	24.5	(200.9)	(6.0)	(198.5)
Operating income (loss)	(16.7)	(35.9)	(145.3)	104.9
Realized and unrealized gains (losses) on derivative contracts	(66.0)	(88.0)	14.9	(168.9)
Interest and other income (expense)	3.8	0.8	1.2	3.7
Interest expense	(36.2)	(45.0)	(73.0)	(86.9)
Income (loss) before income taxes	(115.1)	(168.0)	(202.2)	(147.1)
Income taxes	38.8	61.9	70.3	53.7
Income from continuing operations	(76.3)	(106.1)	(131.9)	(93.4)
NET INCOME (LOSS)	0.0	13.8	0.0	40.8
Net income (loss)	(76.3)	(92.3)	(131.9)	(52.6)
Income from unconsolidated affiliates	$ 0.0	$ 0.1	$ 0.0	$ 0.1