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Business Combinations and Asset Acquisitions - Pro Forma (Details) - Umpqua Bank and Columbia Banking System Merger - USD ($) $ in Thousands | 6 Months Ended
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Jun. 30, 2023 | Jun. 30, 2022
Asset Acquisition [Line Items] |  |
Business acquisition, pro forma net interest income | $ 1,014,447 | $ 959,039
Business Acquisition, Pro Forma Non-interest Income | 128,250 | 179,091
Business Acquisition, Pro Forma Net Income (Loss) | 381,212 | $ 185,660
Business Combination, Acquisition Related Costs - Combined for proforma | $ 173,500 |

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