Income Taxes - Income Tax Expense (Benefit) Attributable to Continuing Operations (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Current
U.S. federal and state	$ 6	$ (18)	$ 12
Non-U.S.	98	74	80
Total current	104	56	92
Deferred
U.S. federal and state	164	(497)	(9)
Non-U.S.	15	17	(1)
Total deferred	179	(480)	(10)
Total expense (benefit)	$ 283	$ (424)	$ 82