Reserves For Losses (Details 3) - USD ($) $ in Millions	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Card Member Loans And Related Reserves Evaluated Separately And Collectively For Impairment [Abstract]
Card Member loans evaluated separately for impairment	$ 279	$ 286	$ 356
Reserves on Card Member loans evaluated separately for impairment	53	67	78
Card Member loans evaluated collectively for impairment	58,294	70,099	66,882
Reserves on Card Member loans evaluated collectively for impairment	$ 975	$ 1,134	$ 1,183