CONDENSED CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME (Unaudited) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 188	$ 199	$ 858	$ 713
Other comprehensive income (loss):
Foreign currency translation adjustment	9	0	36	(20)
Unrealized gains (losses) on forward contracts designated as hedges, net of tax	(8)	(4)	(45)	0
Unrealized gains (losses) on investments, net of tax	(3)	0	(4)	0
Total other comprehensive loss	(2)	(4)	(13)	(20)
Comprehensive income	$ 186	$ 195	$ 845	$ 693