Deposit Accounts (Contractual Maturities of Time Deposits over $250,000) (Details) - USD ($) $ in Millions |
Dec. 31, 2015 |
Dec. 31, 2014 |
|---|---|---|
| Contractual Maturities, Certificates of Deposit, $100,000 or More [Abstract] | ||
| Three months or less | $ 97 | $ 93 |
| Over three months to six months | 72 | 54 |
| Over six months to twelve months | 173 | 103 |
| One to two years | 17 | 9 |
| Thereafter | 37 | 5 |
| Total | $ 396 | $ 264 |