Business Combinations and Asset Acquisitions - Merger related expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Asset Acquisition [Line Items]
Business Combination, Acquisition Related Costs - Communication	$ 20,000	$ 0
Merger-related expenses	171,659	17,356	$ 15,183
Umpqua Bank and Columbia Banking System Merger
Asset Acquisition [Line Items]
Business combination, acquisition related costs, Legal and Professional Fees	61,857	6,202
Business Combination, Acquisition Related Costs - Personnel	38,265	1,124
Business Combination, Acquisition Related Costs - Premises and Equipment	45,374	9,374
Business Combination, Acquisition Related Costs - Other	6,163	656
Merger-related expenses	$ 171,659	$ 17,356