Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (995)	$ (897)
Other comprehensive income/(loss) before reclassifications	68	171
Amounts reclassified from accumulated other comprehensive (income)/loss	14	2
Other comprehensive income/(loss)	82	173
Balance at end of period	(913)	(724)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(994)	(897)
Other comprehensive income/(loss) before reclassifications	80	172
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0
Other comprehensive income/(loss)	80	172
Balance at end of period	(914)	(725)
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(1)	0
Other comprehensive income/(loss) before reclassifications	(12)	(1)
Amounts reclassified from accumulated other comprehensive (income)/loss	14	2
Other comprehensive income/(loss)	2	1
Balance at end of period	$ 1	$ 1