Taxes - Effective Income Tax Reconciliation (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Income (loss) before income taxes
United States	$ (5,700)	$ (5,483)	$ 4,730
International	(1,753)	11,019	15,845
Income (Loss) Before Income Tax Expense	(7,453)	5,536	20,575
Effective Income Tax Rate Reconciliation, Amount [Abstract]
Theoretical tax (at U.S. statutory rate of 21% )	(1,565)	1,163	4,321
Effect of U.S. tax reform	0	3	(26)
Equity affiliate accounting effect	211	(687)	(1,526)
Effect of income taxes from international operations*	(39)	2,196	3,132
State and local taxes on income, net of U.S. federal income tax benefit	(65)	(18)	162
Prior year tax adjustments, claims and settlements	(236)	192	(51)
Tax credits	(33)	(18)	(163)
Other U.S.*	(165)	(140)	(134)
Total income tax expense (benefit)	$ (1,892)	$ 2,691	$ 5,715
Effective income tax rate	25.40%	48.60%	27.80%