Income Taxes - Schedule of Income Tax (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Allocation of total income tax
Income tax expense	$ 40,026	$ 46,801	$ 17,672
Shareholders’ equity for unrealized gain/(loss) on securities available-for-sale	(45,321)	(10,425)	5,061
Shareholders’ equity for pension adjustment	6,980	9,659	(3,774)
Unallocated income tax	1,685	46,035	18,959
Current tax provision/(benefit):
Federal	36,235	24,554	23,968
State	9,295	9,933	1,788
Total current tax provision/(benefit)	45,530	34,487	25,756
Deferred tax provision/(benefit):
Federal	(5,325)	10,752	(9,072)
State	(179)	1,562	988
Total deferred tax provision/(benefit)	(5,504)	12,314	(8,084)
Total provision for income taxes	$ 40,026	$ 46,801	$ 17,672
Reconciliation of the expected federal statutory income tax rate to the effective rate
Expected tax rate	21.00%	21.00%	21.00%
Tax-exempt interest income	(1.10%)	(0.90%)	(1.70%)
State income tax, net of federal benefit	4.00%	4.50%	2.20%
Bank-owned life insurance	(0.90%)	(0.60%)	(1.10%)
Stock-based compensation	0.10%	(0.10%)	0.20%
Dividends on stock plans	(0.50%)	(0.40%)	(0.90%)
Low income housing and historic tax credits	(0.20%)	(0.20%)	(0.90%)
Other	0.60%	0.00%	0.30%
Effective tax rate	23.00%	23.30%	19.10%
Deferred tax assets:
Deferred compensation expense	$ 4,804	$ 4,230
Bad debts	27,105	23,273
Other reserves	3,554	1,333
Accrued post-retirement benefit cost	502	900
Stock benefit plans	652	623
Pension and post-retirement benefits	2,767	9,747
Unrealized loss on the fair value of securities available-for-sale	49,414	4,093
Deferred income	95	341
Lease liability	13,101	12,958
Purchase accounting	696	432
Net operating loss	1,592	2,140
Other	1,877	922
Total deferred tax assets	106,159	60,992
Deferred tax liabilities:
Pension expense	6,231	6,993
Intangible assets	17,400	16,543
Mortgage servicing rights	1,768	2,278
Fixed assets	6,518	5,287
Net deferred loan costs	3,055	2,338
Right of use asset	12,463	12,322
Interest rate derivatives	123	341
Other	2,369	2,503
Total deferred tax liabilities	49,927	48,605
Net deferred tax asset	$ 56,232	$ 12,387