Income Taxes - Significant Components of Temporary Differences (Details) - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020
Deferred Tax Assets:
Allowance for credit losses	$ 22,083	$ 26,051
Lease liabilities	10,876	11,368
State net operating loss carryforwards	5,565	5,489
Net adjustment to funded status of pension	3,922	4,692
Low income housing partnerships	3,270	3,996
Other employee benefits	3,433	2,050
Other	3,973	3,798
Gross Deferred Tax Assets	53,122	57,444
Less: Valuation allowance	(5,565)	(5,489)
Total Deferred Tax Assets	47,557	51,955
Deferred Tax Liabilities:
Right-of-use lease assets	(9,603)	(10,141)
Net unrealized gains on securities available-for-sale	(2,004)	(7,125)
Deferred loan income	(6,697)	(6,796)
Prepaid pension	(4,566)	(5,209)
Purchase accounting adjustments	(1,954)	(1,971)
Depreciation on premises and equipment	(1,107)	(1,275)
Other	(1,466)	(1,245)
Total Deferred Tax liabilities	(27,397)	(33,762)
Net Deferred Tax Asset	$ 20,160	$ 18,193