Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (763)	$ 121	$ (364)	$ 117
Other comprehensive income/(loss) before reclassifications	134	30	(266)	33
Amounts reclassified from accumulated other comprehensive income/(loss)	1	1	2	2
Other comprehensive income/(loss)	135	31	(264)	35
Balance at end of period	(628)	152	(628)	152
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(760)	127	(359)	122
Other comprehensive income/(loss) before reclassifications	134	32	(267)	37
Amounts reclassified from accumulated other comprehensive income/(loss)	0	0	0	0
Other comprehensive income/(loss)	134	32	(267)	37
Balance at end of period	(626)	159	(626)	159
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(3)	(6)	(5)	(5)
Other comprehensive income/(loss) before reclassifications	0	(2)	1	(4)
Amounts reclassified from accumulated other comprehensive income/(loss)	1	1	2	2
Other comprehensive income/(loss)	1	(1)	3	(2)
Balance at end of period	$ (2)	$ (7)	$ (2)	$ (7)