Operations by Line of Business (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues
Total Revenues	$ 772.8	$ 542.4	$ 2,220.3	$ 1,644.9
Operating expenses
Purchased gas, oil and NGL expense	205.0	142.6	608.8	455.9
Lease operating expense	45.0	42.2	127.4	122.8
Natural gas, oil and NGL transportation and other handling costs	34.5	36.3	105.8	111.5
Gathering, processing and other	22.4	22.1	66.5	66.4
General and administrative	49.3	41.7	136.2	114.5
Production and property taxes	42.5	24.3	117.7	68.4
Depreciation, depletion and amortization	253.1	234.6	757.1	648.3
Other operating expenses	5.6	11.2	13.5	77.2
Total Operating Expenses	657.4	555.0	1,933.0	1,665.0
Net (loss) gain from asset sales	12.8	0	113.0	1.5
Operating (loss) income	128.2	(12.6)	400.3	(18.6)
Realized and unrealized gains (losses) on derivative contracts	(27.8)	36.1	51.6	334.7
Interest and other income	4.0	(0.2)	9.1	2.4
Income from unconsolidated affiliates	0.8	2.3	3.7	5.6
Loss from early extinguishment of debt	0	0	0	(0.6)
Interest expense	(41.7)	(30.0)	(122.5)	(82.9)
Income (loss) before income taxes	63.5	(4.4)	342.2	240.6
Income taxes	(22.4)	2.3	(125.0)	(86.5)
Net (loss) income	41.1	(2.1)	217.2	154.1
Net income attributable to noncontrolling interest	(3.8)	(1.0)	(5.8)	(2.7)
Net income (loss) attributable to QEP	37.3	(3.1)	211.4	151.4
Unaffiliated customers [Member]
Revenues
Total Revenues	772.8	542.4	2,220.3	1,644.9
Affiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
QEP Energy [Member]
Revenues
Total Revenues	538.5	374.0	1,575.2	1,106.3
Operating expenses
Purchased gas, oil and NGL expense	39.2	45.9	159.8	159.0
Lease operating expense	43.5	43.1	130.2	125.3
Natural gas, oil and NGL transportation and other handling costs	65.1	59.8	180.8	167.4
Gathering, processing and other	0	0	0	0
General and administrative	33.5	31.6	100.2	92.7
Production and property taxes	40.4	22.5	112.7	63.6
Depreciation, depletion and amortization	236.0	218.5	712.1	600.2
Other operating expenses	5.6	11.2	13.5	77.2
Total Operating Expenses	463.3	432.6	1,409.3	1,285.4
Net (loss) gain from asset sales	12.8		113.4	1.5
Operating (loss) income	88.0	(58.6)	279.3	(177.6)
Realized and unrealized gains (losses) on derivative contracts	(25.6)	41.4	49.6	330.4
Interest and other income	2.6	(0.2)	7.5	2.2
Income from unconsolidated affiliates	0	0	0	0.1
Loss from early extinguishment of debt		0		0
Interest expense	(49.2)	(24.1)	(143.4)	(71.1)
Income (loss) before income taxes	15.8	(41.5)	193.0	84.0
Income taxes	(6.2)	15.3	(71.1)	(32.4)
Net (loss) income	9.6	(26.2)	121.9	51.6
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	9.6	(26.2)	121.9	51.6
QEP Energy [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	538.5	374.0	1,575.2	1,106.3
QEP Energy [Member] | Affiliated customers [Member]
Revenues
Total Revenues	0	0	0	0
QEP Field Services [Member]
Revenues
Total Revenues	100.1	109.7	295.0	343.0
Operating expenses
Purchased gas, oil and NGL expense	0	4.9	8.6	9.0
Lease operating expense	0	0	0	0
Natural gas, oil and NGL transportation and other handling costs	3.4	6.9	11.6	27.7
Gathering, processing and other	22.0	21.8	65.3	65.6
General and administrative	15.8	10.5	36.2	23.7
Production and property taxes	2.0	1.7	4.8	4.6
Depreciation, depletion and amortization	16.8	15.9	44.3	47.6
Other operating expenses	0	0	0	0
Total Operating Expenses	60.0	61.7	170.8	178.2
Net (loss) gain from asset sales	0		(0.4)	0
Operating (loss) income	40.1	48.0	123.8	164.8
Realized and unrealized gains (losses) on derivative contracts	0	(0.6)	0	8.3
Interest and other income	0.8	0	1.1	0.1
Income from unconsolidated affiliates	0.8	2.3	3.7	5.5
Loss from early extinguishment of debt		0		0
Interest expense	(3.2)	(3.5)	(12.5)	(9.4)
Income (loss) before income taxes	38.5	46.2	116.1	169.3
Income taxes	(12.7)	(16.5)	(40.3)	(59.2)
Net (loss) income	25.8	29.7	75.8	110.1
Net income attributable to noncontrolling interest	(3.8)	(1.0)	(5.8)	(2.7)
Net income (loss) attributable to QEP	22.0	28.7	70.0	107.4
QEP Field Services [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	66.9	77.9	203.6	254.9
QEP Field Services [Member] | Affiliated customers [Member]
Revenues
Total Revenues	33.2	31.8	91.4	88.1
QEP Marketing and Other [Member]
Revenues
Total Revenues	440.2	236.3	1,153.2	680.0
Operating expenses
Purchased gas, oil and NGL expense	438.2	236.7	1,150.6	681.7
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	0.4	0.1	1.2	0.8
General and administrative	1.1	1.2	3.3	2.6
Production and property taxes	0.1	0.1	0.2	0.2
Depreciation, depletion and amortization	0.3	0.2	0.7	0.5
Other operating expenses	0	0	0	0
Total Operating Expenses	440.1	238.3	1,156.0	685.8
Net (loss) gain from asset sales	0		0	0
Operating (loss) income	0.1	(2.0)	(2.8)	(5.8)
Realized and unrealized gains (losses) on derivative contracts	(2.2)	(4.7)	2.0	(4.0)
Interest and other income	52.3	28.4	158.2	81.1
Income from unconsolidated affiliates	0	0	0	0
Loss from early extinguishment of debt		0		(0.6)
Interest expense	(41.0)	(30.8)	(124.3)	(83.4)
Income (loss) before income taxes	9.2	(9.1)	33.1	(12.7)
Income taxes	(3.5)	3.5	(13.6)	5.1
Net (loss) income	5.7	(5.6)	19.5	(7.6)
Net income attributable to noncontrolling interest	0	0	0	0
Net income (loss) attributable to QEP	5.7	(5.6)	19.5	(7.6)
QEP Marketing and Other [Member] | Unaffiliated customers [Member]
Revenues
Total Revenues	167.4	90.5	441.5	283.7
QEP Marketing and Other [Member] | Affiliated customers [Member]
Revenues
Total Revenues	272.8	145.8	711.7	396.3
Elimination [Member]
Revenues
Total Revenues	(306.0)	(177.6)	(803.1)	(484.4)
Operating expenses
Purchased gas, oil and NGL expense	(272.4)	(144.9)	(710.2)	(393.8)
Lease operating expense	1.5	(0.9)	(2.8)	(2.5)
Natural gas, oil and NGL transportation and other handling costs	(34.0)	(30.4)	(86.6)	(83.6)
Gathering, processing and other	0	0.2	0	0
General and administrative	(1.1)	(1.6)	(3.5)	(4.5)
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	(306.0)	(177.6)	(803.1)	(484.4)
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	(51.7)	(28.4)	(157.7)	(81.0)
Income from unconsolidated affiliates	0	0	0	0
Loss from early extinguishment of debt		0		0
Interest expense	51.7	28.4	157.7	81.0
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	$ (306.0)	$ (177.6)	$ (803.1)	$ (484.4)