Income Taxes - Schedule of Significant Components of the Company's Deferred Tax Liabilities and Assets (Details) - USD ($) $ in Thousands	Dec. 31, 2022	Dec. 31, 2021
Deferred Tax Liabilities:
Accelerated Depreciation	$ (7,958)	$ (8,131)
Accrued Pension Cost	(11,270)	(11,270)
Federal Home Loan Bank of Des Moines Stock	(6,597)	(2,885)
Lease Transactions	(25,741)	(37,585)
Operating Lease Liabilities	(24,469)	(25,348)
Investment in Variable Interest Entities	(700)	(1,657)
Deferred Loan Fees	(4,798)	(3,845)
Originated Mortgage Servicing Rights	(6,008)	(6,068)
Other	(909)	(915)
Gross Deferred Tax Liabilities	(88,450)	(97,704)
Deferred Tax Assets:
Allowance for Credit Losses	40,056	43,348
Minimum Pension Liability	9,046	12,082
Accrued Expenses	20,066	22,416
Postretirement Benefit Obligations	7,005	7,170
Capital Lease Expenses	2,156	2,163
Operating Lease Right-of-Use Assets	26,648	27,360
Restricted Stock	5,988	4,442
Net Unrealized Losses on Investments Securities	147,716	11,868
Deductible State and Local Taxes	2,360	3,239
Low Income Housing Investments	5,349	3,007
Other	5,995	6,089
Gross Deferred Tax Assets Before Valuation Allowance	272,385	143,184
Valuation Allowance	(6,222)	(3,203)
Gross Deferred Tax Assets After Valuation Allowance	266,163	139,981
Net Deferred Tax Assets	$ 177,713	$ 42,277