Reserves For Losses (Details 1) - USD ($) $ in Millions |
Jun. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Card Member Loans And Related Reserves Evaluated Separately And Collectively For Impairment [Abstract] | ||
| Card Member loans evaluated individually for impairment | $ 342 | $ 279 |
| Reserves on Card Member loans evaluated individually for impairment | 62 | 53 |
| Card Member loans evaluated collectively for impairment | 59,545 | 58,294 |
| Reserves on Card Member loans evaluated collectively for impairment | $ 1,029 | $ 975 |