Oil and Natural Gas Property Transactions - Narrative (Details) MMcf in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($) well MMcf	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) a well MMcf	Jun. 30, 2016 USD ($)
Business Acquisition [Line Items]
Proceeds from divestitures of proved and unproved properties			$ 951,000,000	$ 964,000,000
Corporate VPP [Member]
Business Acquisition [Line Items]
Payments to Acquire Oil and Gas Property				259,000,000
Gain (Loss) on Disposition of Other Assets			0
Haynesville Shale [Member]
Business Acquisition [Line Items]
Proceeds from divestitures of proved and unproved properties			$ 915,000,000
Number Of Net Acres | a			119,500
Productive Gas Wells, Number of Wells, Net | well	576		576
Haynesville Shale [Member] | Natural Gas [Member]
Business Acquisition [Line Items]
Proved Developed Reserves (Volume) | MMcf	80		80
Other Properties [Member]
Business Acquisition [Line Items]
Proceeds from divestitures of proved and unproved properties	$ 63,000,000	$ 833,000,000	$ 83,000,000	$ 964,000,000