Accumulated Other Comprehensive Income (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Cumulative Translation Adjustment Summary [Roll Forward]
Beginning balance	$ (809)	$ (306)	$ (829)	$ (419)
Net gain/(loss) on Foreign Currency Transaction	8	(364)	28	(251)
Ending balance	$ (801)	$ (670)	$ (801)	$ (670)

Accumulated adjustment, net of tax, that results from the process of translating subsidiary financial statements and foreign equity investments into the reporting currency from the functional currency of the reporting entity, net of reclassification of realized foreign currency translation gains or losses.

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