Fair Values (Details) - USD ($) $ in Millions |
Jun. 30, 2016 |
Dec. 31, 2015 |
|---|---|---|
| Investment securities: | ||
| Equity securities | $ 1 | $ 1 |
| Debt securities and other | 3,891 | 3,758 |
| Derivatives | 1,143 | 544 |
| Total assets | 5,035 | 4,303 |
| Level 1 [Member] | ||
| Investment securities: | ||
| Equity securities | 1 | 1 |
| Debt securities and other | 368 | 409 |
| Derivatives | 0 | 0 |
| Total assets | 369 | 410 |
| Level 2 [Member] | ||
| Investment securities: | ||
| Equity securities | 0 | 0 |
| Debt securities and other | 3,523 | 3,349 |
| Derivatives | 1,143 | 544 |
| Total assets | 4,666 | 3,893 |
| Level 3 [Member] | ||
| Investment securities: | ||
| Equity securities | 0 | 0 |
| Debt securities and other | 0 | 0 |
| Derivatives | 0 | 0 |
| Total assets | $ 0 | $ 0 |