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Income Taxes (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Mar. 31, 2023 | Jun. 30, 2022 | Feb. 28, 2023
Income Tax Contingency [Line Items] |  |  |
Deferred Tax Assets, Net | $ 351.2 |  |
Effective Tax Rate as a Percentage of pre-tax Income (loss) | 25.80% | 25.00% |
Umpqua Bank and Columbia Banking System Merger |  |  |
Income Tax Contingency [Line Items] |  |  |
Deferred Tax Assets, Net |  |  | $ 199.9
Operating Loss Carryforwards |  |  | $ 2.4
State and Local Jurisdiction |  |  |
Income Tax Contingency [Line Items] |  |  |
Operating Loss Carryforwards | $ 42.4 |  |
Deferred Tax Assets, Operating Loss Carryforwards, Not Subject to Expiration | 39.5 |  |
Deferred Tax Assets, Operating Loss Carryforwards, Subject to Expiration | $ 2.9 |  |

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