Reserves For Losses (Details 1) - USD ($) $ in Millions |
Dec. 31, 2016 |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|---|
| Card Member Loans And Related Reserves Evaluated Separately And Collectively For Impairment [Abstract] | |||
| Card Member loans evaluated separately for impairment | $ 346 | $ 279 | $ 286 |
| Reserves on Card Member loans evaluated separately for impairment | 60 | 53 | 67 |
| Card Member loans evaluated collectively for impairment | 64,919 | 58,294 | 70,099 |
| Reserves on Card Member loans evaluated collectively for impairment | $ 1,163 | $ 975 | $ 1,134 |