Unaudited Condensed Consolidated Statements of Comprehensive Income (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Statement of Comprehensive Income [Abstract]
Net income	$ 165	$ 191
Other comprehensive income, net of tax:
Foreign currency translation adjustments, net of $0 tax in 2014 and 2013	(1)	2
Unrealized gains on marketable securities, net of $0 tax in 2014 and 2013	1	1
Other comprehensive income	0	3
Comprehensive income	$ 165	$ 194