Business Combinations and Asset Acquisitions - Schedule of common stock (Details) - Umpqua Bank and Columbia Banking System Merger $ / shares in Units, shares in Thousands, $ in Thousands	Feb. 28, 2023 USD ($) $ / shares shares
Asset Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	208,241
Business Acquisition, Percentage of Voting Interests Acquired	100.00%
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned | $	$ 6,191,008
Columbia Banking System, Inc.
Asset Acquisition [Line Items]
Business Acquisition, Share Price | $ / shares	$ 29.73
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	78,863
Business Acquisition, Percentage of Voting Interests Acquired	37.90%
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned | $	$ 2,344,600
UHC
Asset Acquisition [Line Items]
Business Acquisition, Equity Interest Issued or Issuable, Number of Shares | shares	129,378
Business Acquisition, Percentage of Voting Interests Acquired	62.10%
Business Acquisition, Equity Interest Issued or Issuable, Value Assigned | $	$ 3,846,408