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Business Combinations and Asset Acquisitions - Narrative (Details) $ in Thousands |  | 12 Months Ended |  |  |
--- | --- | --- | --- | --- | ---
Feb. 28, 2023 USD ($) shares | Dec. 31, 2023 USD ($) shares | Feb. 24, 2023 branch | Jan. 20, 2023 branch | Dec. 31, 2022 shares
Asset Acquisition [Line Items] |  |  |  |  |
Common Stock, Shares, Outstanding |  | 208,584,667 |  |  | 129,320,962
Finite-Lived Intangible Asset, Useful Life (in years) |  | 10 years |  |  |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | First Norther Bank of Dixon |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |
Branch locations disposed of by sale - number | branch |  |  |  | 3 |
Disposal Group, Disposed of by Sale, Not Discontinued Operations | 1st Security Bank |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |
Branch locations disposed of by sale - number | branch |  |  | 7 |  |
Umpqua Bank and Columbia Banking System Merger |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |
Business Acquisition, Equity Interest Issued or Issuable, Share Exchange Ratio | 0.5958 |  |  |  |
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | 208,241,000 |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired | 100.00% |  |  |  |
Business Combination, Acquired Receivable, Fair Value | $ | $ 10,884,218 |  |  |  |
Financing Receivable, Purchased with Credit Deterioration, Amount at Purchase Price | $ | $ 402,819 |  |  |  |
Business Combination, Acquisition Related Costs - Combined for proforma | $ |  | $ 199,700 |  |  |
Umpqua Bank and Columbia Banking System Merger | Columbia Banking System, Inc. |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |
Common Stock, Shares, Outstanding | 208,200,000 |  |  |  |
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | 78,863,000 |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired | 37.90% |  |  |  |
Umpqua Bank and Columbia Banking System Merger | UHC |  |  |  |  |
Asset Acquisition [Line Items] |  |  |  |  |
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | 129,378,000 |  |  |  |
Business Acquisition, Percentage of Voting Interests Acquired | 62.10% |  |  |  |

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