Reserves For Losses (Details 3) - USD ($) $ in Millions	Jun. 30, 2015	Dec. 31, 2014
Card Member Loans And Related Reserves Evaluated Separately And Collectively For Impairment [Abstract]
Card Member loans evaluated individually for impairment	$ 319	$ 286
Reserves on Card Member loans evaluated individually for impairment	67	67
Card Member loans evaluated collectively for impairment	68,636	70,099
Reserves on Card Member loans evaluated collectively for impairment	$ 1,065	$ 1,134