Segment and Related Information (Revenue by Geographic Region) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,439	$ 1,324	$ 4,262	$ 3,938
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	885	810	2,635	2,385
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	335	311	971	927
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	145	137	438	416
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 74	$ 66	$ 218	$ 210