Business Combinations and Asset Acquisitions - Merger related expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Asset Acquisition [Line Items]
Business Combination, Acquisition Related Costs - Communication	$ 0	$ 0	$ 20,000	$ 0
Merger related expenses	18,938	769	164,485	5,719
Umpqua Bank and Columbia Banking System Merger
Asset Acquisition [Line Items]
Business combination, acquisition related costs, Legal and Professional Fees	6,038	607	60,565	4,137
Business Combination, Acquisition Related Costs - Personnel	3,575	(158)	33,790	1,151
Business Combination, Acquisition Related Costs - Premises and Equipment	8,706	56	43,981	113
Business Combination, Acquisition Related Costs - Other	619	264	6,149	318
Merger related expenses	$ 18,938	$ 769	$ 164,485	$ 5,719