Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current Income Tax Expense Benefit Continuing Operations [Abstract]
U.S. federal	$ 785	$ (4)	$ 15
U.S. state and local	15	(6)	(4)
Non-U.S.	24	11	20
Total current income tax expense	824	1	31
Deferred income tax expense (benefit):
U.S. federal	58	10	(5)
U.S. state and local	1	1	0
Non-U.S.	(5)	3	12
Total deferred income tax expense	54	14	7
Total income tax expense	$ 878	$ 15	$ 38