Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (791)	$ (628)	$ (897)	$ (364)
Other comprehensive income/(loss) before reclassifications	(14)	(201)	86	(467)
Amounts reclassified from accumulated other comprehensive (income)/loss	7	1	13	3
Other comprehensive income/(loss)	(7)	(200)	99	(464)
Balance at end of period	(798)	(828)	(798)	(828)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(790)	(626)	(897)	(359)
Other comprehensive income/(loss) before reclassifications	(5)	(200)	102	(467)
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0	0	0
Other comprehensive income/(loss)	(5)	(200)	102	(467)
Balance at end of period	(795)	(826)	(795)	(826)
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	1	(2)	0	(5)
Other comprehensive income/(loss) before reclassifications	(10)	(1)	(15)	0
Amounts reclassified from accumulated other comprehensive (income)/loss	7	1	13	3
Other comprehensive income/(loss)	(3)	0	(2)	3
Balance at end of period	(2)	(2)	(2)	(2)
Available-for-sale securities
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(2)	0	0	0
Other comprehensive income/(loss) before reclassifications	1	0	(1)	0
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0	0	0
Other comprehensive income/(loss)	1	0	(1)	0
Balance at end of period	$ (1)	$ 0	$ (1)	$ 0