Securities (Carrying Value of Securities Pledged as Collateral) (Details) $ in Thousands |
Sep. 30, 2018
USD ($)
|
|---|---|
| Debt Securities, Available-for-sale [Line Items] | |
| Debt Securities, Available-for-sale, Restricted | $ 427,902 |
| Washington and Oregon State Public Deposits [Member] | |
| Debt Securities, Available-for-sale [Line Items] | |
| Debt Securities, Available-for-sale, Restricted | 256,078 |
| Federal Reserve Bank Advances [Member] | |
| Debt Securities, Available-for-sale [Line Items] | |
| Debt Securities, Available-for-sale, Restricted | 51,843 |
| Other Securities [Member] | |
| Debt Securities, Available-for-sale [Line Items] | |
| Debt Securities, Available-for-sale, Restricted | $ 119,981 |