Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current income tax expense:
U.S. federal	$ 70	$ 3,408	$ 2,180
U.S. state and local	150	259	272
Non-U.S.	681	387	340
Total current income tax expense	901	4,054	2,792
Deferred income tax expense (benefit):
U.S. federal	276	544	(63)
U.S. state and local	78	(12)	(10)
Non-U.S.	(54)	91	(52)
Total deferred income tax expense	300	623	(125)
Income tax provision (benefit)	$ 1,201	$ 4,677	$ 2,667