Securities (Carrying Value of Securities Pledged as Collateral) (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	$ 467,138	$ 419,383
To Washington and Oregon State To Secure Public Deposits [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	276,343	245,222
To Federal Reserve Bank To Secure Borrowings [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	52,303	52,917
Other Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Restricted	$ 138,492	$ 121,244