Dispositions - Schedule of Pre-tax Income (Loss) Associated with Interests Excluding Financial Statement Impacts Resulting from Asset Sales (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Disposition Of Businesses [Line Items]
Income (Loss) from Continuing Operations Before Income Taxes Excluding Gain / Loss and Impairment	$ 220	$ (5,778)	$ (3,854)
Disposal Group, Disposed of by Sale, Not Discontinued Operations
Disposition Of Businesses [Line Items]
Income (Loss) from Continuing Operations Before Income Taxes Excluding Gain / Loss and Impairment	0	14	(290)
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Equatorial Guinea
Disposition Of Businesses [Line Items]
Income (Loss) from Continuing Operations Before Income Taxes Excluding Gain / Loss and Impairment	0	69	(95)
Disposal Group, Disposed of by Sale, Not Discontinued Operations \| Norway
Disposition Of Businesses [Line Items]
Income (Loss) from Continuing Operations Before Income Taxes Excluding Gain / Loss and Impairment	$ 0	$ (55)	$ (195)

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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