Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (845)	$ (925)
Other comprehensive income/(loss) before reclassifications	(239)	10
Amounts reclassified from accumulated other comprehensive (income)/loss	(61)	(11)
Adjustment to adopt reclassification of certain tax effects from AOCI		97
Other comprehensive income/(loss)	(300)	96
Balance at end of period	(1,145)	(829)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(777)	(889)
Other comprehensive income/(loss) before reclassifications	(306)	13
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0
Adjustment to adopt reclassification of certain tax effects from AOCI		98
Other comprehensive income/(loss)	(306)	111
Balance at end of period	(1,083)	(778)
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(68)	(36)
Other comprehensive income/(loss) before reclassifications	67	(3)
Amounts reclassified from accumulated other comprehensive (income)/loss	(61)	(11)
Adjustment to adopt reclassification of certain tax effects from AOCI		(1)
Other comprehensive income/(loss)	6	(15)
Balance at end of period	$ (62)	$ (51)