Securities (Carrying Value of Securities Pledged as Collateral) (Details) $ in Thousands	Jun. 30, 2017 USD ($)
Schedule of Available-for-sale Securities [Line Items]
Carrying amount of securities pledged as collateral	$ 422,389
Washington and Oregon State Public Deposits [Member]
Schedule of Available-for-sale Securities [Line Items]
Carrying amount of securities pledged as collateral	244,580
Federal Reserve Bank Advances [Member]
Schedule of Available-for-sale Securities [Line Items]
Carrying amount of securities pledged as collateral	54,877
Other Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Carrying amount of securities pledged as collateral	$ 122,932