Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of year	$ (925)	$ (592)	$ (995)
Other comprehensive income/(loss) before reclassifications	31	(204)	358
Amounts reclassified from accumulated other comprehensive (income)/loss	(48)	(129)	45
Adjustment to adopt reclassification of certain tax effects from AOCI	97
Other comprehensive income/(loss)	80	(333)	403
Balance at end of year	(845)	(925)	(592)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of year	(889)	(587)	(994)
Other comprehensive income/(loss) before reclassifications	14	(302)	407
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0	0
Adjustment to adopt reclassification of certain tax effects from AOCI	98
Other comprehensive income/(loss)	112	(302)	407
Balance at end of year	(777)	(889)	(587)
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of year	(36)	(5)	(1)
Other comprehensive income/(loss) before reclassifications	17	98	(49)
Amounts reclassified from accumulated other comprehensive (income)/loss	(48)	(129)	45
Adjustment to adopt reclassification of certain tax effects from AOCI	(1)
Other comprehensive income/(loss)	(32)	(31)	(4)
Balance at end of year	$ (68)	$ (36)	$ (5)