Investment Tax Credit (Narrative) (Details) - USD ($)	Dec. 31, 2023	Feb. 28, 2023	Dec. 31, 2022	Dec. 31, 2021
Asset Acquisition [Line Items]
Unfunded affordable housing tax credit commitments	$ 114,082,000		$ 81,632,000
Proportional amortization	210,873,000		143,719,000
Tax credit impairment adjustment	$ 0		$ 0	$ 0
Umpqua Bank and Columbia Banking System Merger
Asset Acquisition [Line Items]
Unfunded affordable housing tax credit commitments		$ 40,900,000
Proportional amortization		$ 47,200,000