Divestitures - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
	Dec. 31, 2017	Jun. 30, 2019	Jun. 30, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds		$ 31	$ 384
Net losses		$ (1)	(28)
Certain Onshore Domestic Assets Alaska [Member] | Exploration & Production [Member] | Asset Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net proceeds			383
Net losses	$ 154		37
Certain Nonoperated Gulf Of Mexico Assets Ram Powell [Member] | Exploration & Production [Member] | Asset Disposed of by Sale
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Net losses			$ (67)