Accumulated Other Comprehensive Income - Reclassifications out of Accumulated Other Comprehensive Income (Loss) (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Income before income taxes	$ 673	$ 547
Provision for income taxes	(152)	(140)
Interest and other, net	64	(32)
Total, net of income taxes	518	407
Reclassification out of Accumulated Other Comprehensive Income
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Total, net of income taxes	16	(23)
Reclassification out of Accumulated Other Comprehensive Income | Gains (losses) on cash flow hedges - foreign exchange contracts | Foreign Exchange Contract
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Net Revenues	20	(28)
Income before income taxes	20	(28)
Provision for income taxes	(4)	6
Total, net of income taxes	16	(22)
Reclassification out of Accumulated Other Comprehensive Income | Unrealized gains (losses) on investments
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items]
Interest and other, net	0	(1)
Total, net of income taxes	$ 0	$ (1)