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Business Combinations and Asset Acquisitions - Schedule of hypothetical number of shares (Details) - Umpqua Bank and Columbia Banking System Merger shares in Thousands | Feb. 28, 2023 shares
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Asset Acquisition [Line Items] |
Business Acquisition Hypothetical Equity Interests Issued or Issuable | 349,515
Business Acquisition Hypothetical Percentage of Voting Interests Acquired | 1.000
Columbia Banking System, Inc. |
Asset Acquisition [Line Items] |
Business Acquisition Hypothetical Equity Interests Issued or Issuable | 132,365
Business Acquisition Hypothetical Percentage of Voting Interests Acquired | 0.379
UHC |
Asset Acquisition [Line Items] |
Business Acquisition Hypothetical Equity Interests Issued or Issuable | 217,150
Business Acquisition Hypothetical Percentage of Voting Interests Acquired | 0.621

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