Divestitures and Other Transactions - Summary of Revenues and Costs from Discontinued Operations (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Jun. 30, 2020	Sep. 30, 2020	Sep. 30, 2019
Costs and other deductions
Net income of Algeria operations, after taxes	$ 80	$ (15)		$ (1,335)	$ (15)
Algeria Africa Assets \| Discontinued Operations, Disposed of by Sale
Revenues and other income
Net sales		172	$ 319		172
Costs and other deductions
Oil and gas lease operating expense		12	44		12
Transportation expense		4	14		4
Taxes other than on income		46	48		46
Depreciation, depletion and amortization		61	110		61
Impairment upon reclassification to held for use		0	931		0
Other		2	10		2
Total costs and other deductions		125	1,157		125
Income (losses) before income taxes		47	(838)		47
Income tax expense		(47)	(95)		(47)
Net income of Algeria operations, after taxes		$ 0	$ (933)		$ 0

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