Segment and Related Information - Revenue by Geographic Region (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,567	$ 1,453
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	951	891
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	381	346
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	156	132
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 79	$ 84