Segment and Related Information (Revenue by Geographic Region) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,453	$ 1,341
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	891	840
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	346	297
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	132	137
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 84	$ 67