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Business Combinations and Asset Acquisitions - Pro Forma (Details) - Umpqua Bank and Columbia Banking System Merger - USD ($) $ in Thousands | 12 Months Ended
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Dec. 31, 2023 | Dec. 31, 2022
Asset Acquisition [Line Items] |  |
Business acquisition, pro forma net interest income | $ 1,951,561 | $ 2,056,167
Business Acquisition, Pro Forma Non-interest Income | 237,764 | 288,417
Business Acquisition, Pro Forma Net Income (Loss) | 633,719 | $ 550,727
Business Combination, Acquisition Related Costs - Combined for proforma | $ 199,700 |

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