Oil and Natural Gas Property Transactions - VPP Volume Remaining to Be Delivered Table (Details) MMBbls in Millions, Bcf in Millions, Bcfe in Billions	12 Months Ended
	Dec. 31, 2018 Bcfe VPP MMBbls Bcf	Dec. 31, 2016 VPP
VPP Volumes Remaining to be Delivered [Line Items]
VPP | VPP	9	4
VPP 9 Mid-Continent [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Proved developed reserves (energy) | Bcfe	177.0
VPP 9 Mid-Continent [Member] | Oil [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Proved developed reserves (volume)	1.7
VPP 9 Mid-Continent [Member] | Natural gas [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Proved developed reserves (volume) | Bcf	138,000.0
VPP 9 Mid-Continent [Member] | NGL [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Proved developed reserves (volume)	4.8
VPP 9 Mid-Continent [Member] | Reserve volume remaining [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Term Remaining (in Months)	26 months
Proved developed reserves (energy) | Bcfe	28.1
VPP 9 Mid-Continent [Member] | Reserve volume remaining [Member] | Oil [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Proved developed reserves (volume)	0.2
VPP 9 Mid-Continent [Member] | Reserve volume remaining [Member] | Natural gas [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Proved developed reserves (volume) | Bcf	23.1
VPP 9 Mid-Continent [Member] | Reserve volume remaining [Member] | NGL [Member]
VPP Volumes Remaining to be Delivered [Line Items]
Proved developed reserves (volume)	0.6