Acquisitions and Divestitures - Additional Information - 2015 Activity - Other (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015		Dec. 31, 2014
Business Combinations [Abstract]
Leasehold and property acquisition	$ 181	$ 367	[1]	$ 1,475	[1]
Proceeds from Divestiture of Businesses	134	268		96
Gain (loss) on divestiture of other oil and gas properties	$ 21	$ 135		$ (216)

[1] Financial information for 2015 and 2014 has been recast to reflect retrospective application of the successful efforts method of accounting. See Note 1.