Reserves For Losses (Details 1) - USD ($) $ in Millions	Mar. 31, 2017	Dec. 31, 2016
Card Member Loans And Related Reserves Evaluated Separately And Collectively For Impairment [Abstract]
Card Member loans evaluated individually for impairment	$ 345	$ 346
Reserves on Card Member loans evaluated individually for impairment	60	60
Card Member loans evaluated collectively for impairment	63,223	64,919
Reserves on Card Member loans evaluated collectively for impairment	$ 1,188	$ 1,163