Income Taxes (Components of Income Tax Expense (Benefit)) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Current tax expense (benefit):
U.S.	$ (571)	$ 86	$ (346)
State and local	11	2	7
Foreign	848	879	681
Total current tax expense (benefit)	288	967	342
Deferred tax expense (benefit):
U.S.	(362)	57	80
State and local	1	(1)	1
Foreign	(8)	(76)	399
Total deferred tax expense (benefit)	(369)	(20)	480
Total income tax expense (benefit) on income (loss) before equity in earnings of operating joint ventures	(81)	947	822
Income tax expense (benefit) on equity in earnings of operating joint ventures	47	43	31
Income tax expense (benefit) on discontinued operations	0	0	0
Income tax expense (benefit) reported in equity related to:
Other comprehensive income (loss)	1,252	3,811	(1,812)
Stock-based compensation programs	0	0	0
Total income taxes	$ 1,218	$ 4,801	$ (959)