Accumulated Other Comprehensive Income/(Loss) (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	$ (829)	$ (533)	$ (925)	$ (592)
Other comprehensive income/(loss) before reclassifications	1	(155)	11	(116)
Amounts reclassified from accumulated other comprehensive (income)/loss	(3)	(96)	(14)	(76)
Adjustment to adopt reclassification of certain tax effects from AOCI			97
Other comprehensive income/(loss)	(2)	(251)	94	(192)
Balance at end of period	(831)	(784)	(831)	(784)
Foreign currency translation
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(778)	(522)	(889)	(587)
Other comprehensive income/(loss) before reclassifications	20	(254)	33	(189)
Amounts reclassified from accumulated other comprehensive (income)/loss	0	0	0	0
Adjustment to adopt reclassification of certain tax effects from AOCI			98
Other comprehensive income/(loss)	20	(254)	131	(189)
Balance at end of period	(758)	(776)	(758)	(776)
Derivative financial instruments
Accumulated Other Comprehensive Income (Loss) [Line Items]
Balance at beginning of period	(51)	(11)	(36)	(5)
Other comprehensive income/(loss) before reclassifications	(19)	99	(22)	73
Amounts reclassified from accumulated other comprehensive (income)/loss	(3)	(96)	(14)	(76)
Adjustment to adopt reclassification of certain tax effects from AOCI			(1)
Other comprehensive income/(loss)	(22)	3	(37)	(3)
Balance at end of period	$ (73)	$ (8)	$ (73)	$ (8)

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Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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Amount after tax, before reclassification adjustments of other comprehensive income (loss).

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Amount after tax of other comprehensive income (loss) attributable to parent entity.

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