Segment and Related Information - Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,513	$ 1,439	$ 4,475	$ 4,262
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	916	887	2,733	2,641
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	359	333	1,062	966
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	157	145	431	437
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 81	$ 74	$ 249	$ 218