Income Taxes - Reconciliation of Beginning and Ending Balances of Total Amounts of Gross Unrecognized Tax Benefits (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning balance	$ 61	$ 95	$ 130
Additions to prior years' tax positions	4	0	1
Reductions to prior years' tax positions	(6)	(7)	(12)
Additions to current year tax positions	2	1	7
Reductions in tax positions due to lapse of statutory limitations	(5)	(16)	(6)
Settlements	0	(2)	(20)
Foreign currency translation	3
Foreign currency translation		(10)	(5)
Ending balance	$ 59	$ 61	$ 95