Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), balance at beginning of period	$ (303)	$ 68
Other comprehensive income (loss) before reclassifications	(240)	(24)
Amounts reclassified from accumulated other comprehensive income (loss)	(2)
Accumulated other comprehensive income (loss), balance at end of period	(545)	44
Foreign currency translation adjustments
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), balance at beginning of period	(304)	67
Other comprehensive income (loss) before reclassifications	(245)	(24)
Amounts reclassified from accumulated other comprehensive income (loss)	0
Accumulated other comprehensive income (loss), balance at end of period	(549)	43
Unrealized gain (loss) on forward contracts
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), balance at beginning of period	0	0
Other comprehensive income (loss) before reclassifications	8	0
Amounts reclassified from accumulated other comprehensive income (loss)	(2)
Accumulated other comprehensive income (loss), balance at end of period	6	0
Unrealized gain (loss) on available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Roll Forward]
Accumulated other comprehensive income (loss), balance at beginning of period	1	1
Other comprehensive income (loss) before reclassifications	(3)	0
Amounts reclassified from accumulated other comprehensive income (loss)	0
Accumulated other comprehensive income (loss), balance at end of period	$ (2)	$ 1