Segment and Related Information (Revenue by Geographic Region) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 1,341	$ 1,273
U.S.
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	840	765
European region
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	297	307
Asia
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	137	128
Rest of the world
Revenues from External Customers and Long-Lived Assets [Line Items]
Revenue	$ 67	$ 73