Reserves for Losses (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2016	Sep. 30, 2015	Sep. 30, 2016	Sep. 30, 2015
Changes in the Card Member loans reserve for losses
Balance, January 1			$ 1,028	$ 1,201
Card Member loans - provisions	$ 319	$ 309	831	829
Card Member loans net write-offs - principal			(687)	(733)
Card Member loans net write-offs - interest and fees			(128)	(122)
Card Member loans reserves for losses - other			70	(11)
Balance, September 30	$ 1,114	$ 1,164	$ 1,114	$ 1,164