Reserves (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Changes in the Card Member receivable reserve for losses
Balance, January 1	$ 94	$ 76
Provisions	71	105
Other credits	32	15
Net write-offs	(84)	(92)
Other debits	(7)	0
Balance, June 30	$ 106	$ 104