Segment and Geographical Information - Net Revenues by Major Products and Services (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenue from External Customer [Line Items]
Net revenues	$ 2,297	$ 1,983	$ 4,434	$ 3,857
Transaction revenues
Revenue from External Customer [Line Items]
Net revenues	1,970	1,712	3,884	3,386
Other value added services
Revenue from External Customer [Line Items]
Net revenues	$ 327	$ 271	$ 550	$ 471