Derivatives and Hedging Activities (Details 2) - Not Designated as Hedging Instrument [Member] - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	$ (15)	$ 2	$ 13	$ 88
Other Expense [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	0	0	0	0
Other Expense [Member] | Foreign exchange contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	(19)	2	15	84
Cost Of Card Member Services [Member] | Foreign exchange contracts [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	$ 4	$ 0	$ (2)	$ 4