Income Taxes - Provision for Income Taxes (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Current
Non-U.S.	$ 22	$ 40	$ 41
Deferred
U.S. federal	(4)	(1)	2
Non-U.S.	24	(9)	(4)
Total income tax expense	$ 42	$ 30	$ 38