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Business Combinations and Asset Acquisitions - PCD Loans (Details) - USD ($) $ in Thousands |  | 12 Months Ended
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Feb. 28, 2023 | Dec. 31, 2023
Asset Acquisition [Line Items] |  |
Initial ACL on PCD loans acquired during the period |  | $ 26,492
Umpqua Bank and Columbia Banking System Merger |  |
Asset Acquisition [Line Items] |  |
Financing Receivable, Purchased with Credit Deterioration, Amount at Par Value | $ 478,648 |
Initial ACL on PCD loans acquired during the period | 26,492 |
Financing Receivable, Purchased with Credit Deterioration, Discount (Premium) | (49,337) |
Financing Receivable, Purchased with Credit Deterioration, Amount at Purchase Price | $ 402,819 |

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