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Summary of Significant Accounting Policies (Details) | 12 Months Ended
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Dec. 31, 2018 USD ($) location | Dec. 31, 2017 USD ($) | Dec. 31, 2016 USD ($)
Accounting Policies [Line Items] |  |  |
FHLB membership stock purchase requirement cap | $ 10,000,000 |  |
Gain on sale of merchant card services portfolio | $ 0 | $ 14,000,000 | $ 0
Number Of Branch Locations | location | 150 |  |
Number Of Days Used To Determine Treatment As Cash Equivalent | 90 days |  |
Number of Days of Delinquency at Which Loans Are Categorized As Non Accrual Status | 90 days |  |
Loans and Leases Receivable, Nonaccrual Loans Considered Impaired | $ 500,000 |  |
Loans and Leases Receivable, Loans Evaluated For Impairment On Quarterly Basis, Outstanding | 500,000 |  |
Federal Home Loan Bank stock, par value | $ 100 |  |
Core Deposits [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Estimated life of CDI, in years | 10 years |  |
WASHINGTON |  |  |
Accounting Policies [Line Items] |  |  |
Number Of Branch Locations | location | 74 |  |
OREGON |  |  |
Accounting Policies [Line Items] |  |  |
Number Of Branch Locations | location | 62 |  |
IDAHO |  |  |
Accounting Policies [Line Items] |  |  |
Number Of Branch Locations | location | 14 |  |
Vehicles [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | P5Y |  |
Minimum [Member] | Building and Building Improvements [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | P5Y |  |
Minimum [Member] | Furniture and Fixtures [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | P3Y |  |
Minimum [Member] | Software [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | P3Y |  |
Maximum [Member] | Building and Building Improvements [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | P39Y |  |
Maximum [Member] | Furniture and Fixtures [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | P7Y |  |
Maximum [Member] | Software [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Property, Plant and Equipment, Estimated Useful Lives | P5Y |  |
Accounting Standards Update 2016-02 [Member] |  |  |
Accounting Policies [Line Items] |  |  |
New Accounting Pronouncement, Early Adoption [Table Text Block] | $ 49,200,000 |  |
Expected change in other liabilities due to adoption of new ASU | 48,200,000 |  |
Accounting Standards Update 2016-02 [Member] | Retained Earnings [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption | $ 1,000,000 |  |
Accounting Standards Update 2018-02 [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  | 0
Accounting Standards Update 2018-02 [Member] | Retained Earnings [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  | 4,082,000
Accounting Standards Update 2016-09 [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  | 67,000
Accounting Standards Update 2016-09 [Member] | Retained Earnings [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  | (117,000)
Accounting Standards Update 2016-09 [Member] | Common Stock [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  |  | $ 184,000
Accounting Standards Update 2016-01 [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  | 0 |
Accounting Standards Update 2016-01 [Member] | Retained Earnings [Member] |  |  |
Accounting Policies [Line Items] |  |  |
Cumulative Effect of New Accounting Principle in Period of Adoption |  | $ (157,000) |

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