Reserves for Losses (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Changes in the Card Member loans reserve for losses
Balance, January 1			$ 1,028	$ 1,201
Card Member loans - provisions	$ 285	$ 285	512	520
Card Member loans net write-offs - principal			(437)	(502)
Card Member loans net write-offs - interest and fees			(80)	(85)
Card Member loans - other			68	(2)
Balance, March 31	$ 1,091	$ 1,132	$ 1,091	$ 1,132