CONSOLIDATED STATEMENTS OF COMPREHENSIVE INCOME - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Statement of Comprehensive Income [Abstract]
Net income	$ 1,813	$ 273	$ 966
Other comprehensive income (loss):
Foreign currency translation adjustments, net of tax	(9)	36	(29)
Unrealized gains (losses) on forward contracts designated as hedges, net of tax	38	(44)	33
Unrealized gains (losses) on investments, net of tax	5	(1)	0
Total other comprehensive income (loss)	34	(9)	4
Comprehensive income	$ 1,847	$ 264	$ 970