Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of year	$ (897)	$ (364)	$ 117
Other comprehensive income/(loss) before reclassifications	(82)	(536)	(485)
Amounts reclassified from accumulated other comprehensive (income)/loss	(16)	3	4
Other comprehensive income/(loss)	(98)	(533)	(481)
Balance at end of year	(995)	(897)	(364)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of year	(897)	(359)	122
Other comprehensive income/(loss) before reclassifications	(97)	(538)	(481)
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0	0
Other comprehensive income/(loss)	(97)	(538)	(481)
Balance at end of year	(994)	(897)	(359)
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of year	0	(5)	(5)
Other comprehensive income/(loss) before reclassifications	15	2	(4)
Amounts reclassified from accumulated other comprehensive (income)/loss	(16)	3	4
Other comprehensive income/(loss)	(1)	5	0
Balance at end of year	$ (1)	$ 0	$ (5)