Supplemental Gas and Oil Information (Unaudited) Estimated Quantities of Proved Gas and Oil Reserves (Details) MMBoe in Millions, MMBbls in Millions, Bcf in Billions		12 Months Ended
		Dec. 31, 2018 MMBoe Bcf MMBbls		Dec. 31, 2017 MMBoe Bcf MMBbls		Dec. 31, 2016 MMBoe Bcf MMBbls
Oil [Member]
Reserve Quantities [Line Items]
Proved reserves balance, beginning balance		320.5		238.6		193.1
Revisions of previous estimates		2.1	[1]	3.7	[2]	(9.7)	[3]
Extensions and discoveries		57.1	[4]	59.1	[5]	13.0	[6]
Purchase of reserves in place		8.2	[7]	46.6	[8]	62.7	[9]
Sale of reserves in place		(24.9)	[10]	(7.9)	[11]	(0.2)	[12]
Production		(23.9)		(19.6)		(20.3)
Proved reserves balance, ending balance		339.1		320.5		238.6
Proved undeveloped reserves, beginning balance		204.5		135.4		83.4
Proved undeveloped reserve, ending balance		205.5		204.5		135.4
Proved developed reserves, beginning balance		116.0		103.2		109.7
Proved developed reserves, ending balance		133.6		116.0		103.2
Gas [Member]
Reserve Quantities [Line Items]
Proved reserves balance, beginning balance | Bcf		1,793.6		2,553.8		2,108.9
Revisions of previous estimates | Bcf		314.0	[1]	12.5	[2]	412.8	[3]
Extensions and discoveries | Bcf		56.5	[4]	101.9	[5]	158.1	[6]
Purchase of reserves in place | Bcf		7.9	[7]	125.5	[8]	54.6	[9]
Sale of reserves in place | Bcf		(544.8)	[10]	(831.2)	[11]	(3.6)	[12]
Production | Bcf		(139.6)		(168.9)		(177.0)
Proved reserves balance, ending balance | Bcf		1,487.6		1,793.6		2,553.8
Proved undeveloped reserves, beginning balance | Bcf		1,138.1		1,244.0		863.6
Proved undeveloped reserve, ending balance | Bcf		1,105.3		1,138.1		1,244.0
Proved developed reserves, beginning balance | Bcf		655.5		1,309.8		1,245.3
Proved developed reserves, ending balance | Bcf		382.3		655.5		1,309.8
Natural Gas Liquids [Member]
Reserve Quantities [Line Items]
Proved reserves balance, beginning balance		65.2		67.2		58.8
Revisions of previous estimates		6.7	[1]	(3.1)	[2]	(0.3)	[3]
Extensions and discoveries		9.8	[4]	10.4	[5]	3.3	[6]
Purchase of reserves in place		1.3	[7]	8.7	[8]	11.5	[9]
Sale of reserves in place		(7.1)	[10]	(12.6)	[11]	(0.1)	[12]
Production		(4.7)		(5.4)		(6.0)
Proved reserves balance, ending balance		71.2		65.2		67.2
Proved undeveloped reserves, beginning balance		37.3		31.5		24.4
Proved undeveloped reserve, ending balance		39.7		37.3		31.5
Proved developed reserves, beginning balance		27.9		35.7		34.4
Proved developed reserves, ending balance		31.5		27.9		35.7
Barrels of oil equivalent production [Member]
Reserve Quantities [Line Items]
Proved developed and undeveloped reserves, beginning balance | MMBoe	[13]	684.7		731.4		603.4
Revisions of previous estimates | MMBoe	[13]	61.0	[1]	2.7	[2]	58.8	[3]
Extensions and discoveries | MMBoe	[13]	76.3	[4]	86.4	[5]	42.6	[6]
Purchase of reserves in place | MMBoe	[13]	10.9	[7]	76.3	[8]	83.3	[9]
Sale of reserves in place | MMBoe	[13]	(122.8)	[10]	(159.0)	[11]	(0.9)	[12]
Production | MMBoe	[13]	(51.9)		(53.1)		(55.8)
Proved developed and undeveloped reserves, ending balance | MMBoe	[13]	658.2		684.7		731.4
Proved undeveloped reserves, beginning balance | MMBoe		431.6		374.2		251.8
Proved undeveloped reserves, ending balance | MMBoe		429.3		431.6		374.2
Proved developed reserves, beginning balance | MMBoe		253.1		357.2		351.6
Proved developed reserves, ending balance | MMBoe		228.9		253.1		357.2
Pricing Revisions [Member]
Reserve Quantities [Line Items]
Revisions of previous estimates | MMBoe		17.3		32.0		(18.5)
Performance Revisions [Member]
Reserve Quantities [Line Items]
Revisions of previous estimates | MMBoe		8.7		2.2		5.5
Positive revisions [Member]
Reserve Quantities [Line Items]
Revisions of previous estimates | MMBoe		61.0		2.7		77.3
Operating Cost Revisions [Member]
Reserve Quantities [Line Items]
Revisions of previous estimates | MMBoe		11.7		11.0
Development plan change [Member]
Reserve Quantities [Line Items]
Revisions of previous estimates | MMBoe		23.4		20.5

[1] Revisions of previous estimates in 2018 totaling 61.0 MMboe of positive revisions include 23.4 MMboe of other revisions, primarily related to changing our development plans in the Haynesville/Cotton Valley; 17.3 MMboe of positive revisions related to pricing, primarily driven by higher oil prices; 11.7 MMboe of positive revisions related to lower operating costs; and 8.7 MMboe of positive performance revisions.

[2] Revisions of previous estimates in 2017 include 2.7 MMboe of positive revisions, primarily related to 32.0 MMboe of positive revisions related to pricing, driven by higher oil, gas and NGL prices and 2.2 MMboe of positive performance revisions. These positive revisions were partially offset by 11.0 MMboe of negative revisions related to higher operating costs and 20.5 MMboe of other revisions primarily from changing to a horizontal development plan from a vertical well development plan in the Uinta Basin and increased longer laterals in Haynesville/Cotton Valley. These negative other revisions are partially offset by positive other revisions from successful infill drilling in Haynesville/Cotton Valley and the Williston Basin.

[3] Revisions of previous estimates in 2016 include 77.3 MMboe of positive revisions, primarily related to successful workovers in Haynesville/Cotton Valley; reserves associated with increased density wells in areas that have been previously developed on lower density spacing; and 5.5 MMboe of positive performance revisions. These positive revisions were partially offset by 18.5 MMboe of negative revisions related to pricing, driven by lower oil, gas and NGL prices.

[4] Extensions and discoveries in 2018 primarily related to new well completions and associated new PUD locations in the Permian Basin.

[5] Extensions and discoveries in 2017 primarily related to new well completions and associated new PUD locations in the Permian Basin.

[6] Extensions and discoveries in 2016 were primarily in the Permian and Uinta basins and related to new well completions and associated new PUD locations.

[7] Purchase of reserves in place in 2018 primarily relates to the additional acquisitions in the Permian Basin as discussed in Note 3 – Acquisitions and Divestitures.

[8] Purchase of reserves in place in 2017 was primarily related to QEP's 2017 Permian Basin Acquisition and various other acquired oil and gas properties as discussed in Note 3 – Acquisitions and Divestitures.

[9] Purchase of reserves in place in 2016 primarily relates to QEP's 2016 Permian Basin Acquisition as discussed in Note 3 – Acquisitions and Divestitures.

[10] Sale of reserves in place in 2018 was primarily related to QEP's Uinta Basin Divestiture as discussed in Note 3 – Acquisitions and Divestitures.

[11] Sale of reserves in place in 2018 was primarily related to QEP's Pinedale Divestiture as discussed in Note 3 – Acquisitions and Divestitures.

[12] Sale of reserves in place in 2016 relates to the divestiture of QEP's interest in certain non-core properties as discussed in Note 3 – Acquisitions and Divestitures.

[13] Generally, gas consumed in operations was excluded from reserves, however, in some cases, produced gas consumed in operations was included in reserves when the volumes replaced fuel purchases.