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Premises and Equipment (Narrative) (Details) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2023 | Dec. 31, 2022 | Dec. 31, 2021 | Feb. 28, 2023
Asset Acquisition [Line Items] |  |  |  |
Depreciation and Amortization expense | $ 29,300 | $ 22,900 | $ 25,700 |
Umpqua Bank and Columbia Banking System Merger |  |  |  |
Asset Acquisition [Line Items] |  |  |  |
Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Property, Plant, and Equipment |  |  |  | $ 203,270

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