Segment and Related Information (Revenue by Geographic Region) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,482	$ 1,342	$ 2,823	$ 2,615
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	910	810	1,750	1,575
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	339	310	636	617
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	156	151	293	279
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 77	$ 71	$ 144	$ 144