Derivatives and Hedging Activities (Details 2) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	$ (48)	$ (88)	$ 86	$ 82
Other Expense [Member] | Interest Rate Contract [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	0	1
Other Expense [Member] | Foreign exchange contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	(50)	(89)	83	82
Cost Of Card Member Services [Member] | Foreign exchange contracts [Member] | Not Designated as Hedging Instrument [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Pretax gains (losses)	$ 2	$ 0	$ 3	$ 0