Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2016	Mar. 31, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (897)	$ (364)
Other comprehensive income/(loss) before reclassifications	171	(400)
Amounts reclassified from accumulated other comprehensive (income)/loss	2	1
Other comprehensive income/(loss)	173	(399)
Balance at end of period	(724)	(763)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(897)	(359)
Other comprehensive income/(loss) before reclassifications	172	(401)
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0
Other comprehensive income/(loss)	172	(401)
Balance at end of period	(725)	(760)
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	0	(5)
Other comprehensive income/(loss) before reclassifications	(1)	1
Amounts reclassified from accumulated other comprehensive (income)/loss	2	1
Other comprehensive income/(loss)	1	2
Balance at end of period	$ 1	$ (3)