Dispositions - International E&P Segment (Details) - USD ($) $ in Millions	1 Months Ended	3 Months Ended			12 Months Ended
	Jul. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Surety Bond Exposure, Liability		$ 6			$ 6
Document Period End Date					Dec. 31, 2019
Income (loss) from continuing operations before income taxes					$ 392	$ 1,427	$ (454)
International | U.K. Business [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Disposal of assets, net of cash transferred to the buyer	$ 95
Disposal Group, Including Discontinued Operation, Cash and Cash Equivalents						345
Income (loss) from continuing operations before income taxes					$ 33	261
International | Atrush Block in Kurdistan [Member] | Disposal Group, Held-for-sale, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Assets						58
Liabilities						$ 17
International | Atrush Block in Kurdistan [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage interest in property		15.00%
Disposal of assets, net of cash transferred to the buyer			$ 63
International | Marathon Oil Libya Limited [Member] | Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Percentage interest in property				16.33%
Disposal of assets, net of cash transferred to the buyer				$ 450
Gain (loss) on disposal				$ 255