Shareholders' Equity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Before-Tax Amount
Unrealized loss on securities	$ (23,222)	$ 85,188	$ 73,085
Reclassification adjustment for securities gains included in net income	(33,516)	(3,053)	(4,733)
Amortization of net unrealized losses on available for sale securities transferred to held to maturity	3,485	4,360	8,070
Net unrealized holding loss arising during the period on interest rate swaps used in cash flow hedges	(2,776)
Reclassification adjustment for net loss realized in net income on interest rate swaps used in cash flow hedges	(3,452)
Non-credit related unrealized losses on other-than-temporarily impaired debt securities			(873)
Unrecognized pension and postretirement income	9,147	(3,242)	(1,203)
Amortization of net unrecognized pension and postretirement income	1,480	1,311	1,316
Total Other Comprehensive Loss	(48,854)	84,564	75,662
Tax Effect
Unrealized loss on securities	5,274	(19,537)	(16,166)
Reclassification adjustment for securities gains included in net income	7,611	694	1,047
Amortization of net unrealized losses on available for sale securities transferred to held to maturity	(795)	(912)	(1,785)
Net unrealized holding loss arising during the period on interest rate swaps used in cash flow hedges	629
Reclassification adjustment for net loss realized in net income on interest rate swaps used in cash flow hedges	782
Non-credit related unrealized losses on other-than-temporarily impaired debt securities			193
Unrecognized pension and postretirement income	(2,003)	710	266
Amortization of net unrecognized pension and postretirement income	(324)	(291)	(291)
Total Other Comprehensive Loss	11,174	(19,336)	(16,736)
Other Comprehensive (Loss)/Income, net of tax:
Unrealized loss on securities	(17,948)	65,651	56,919
Reclassification adjustment for securities gains included in net income	(25,905)	(2,359)	(3,686)
Amortization of net unrealized losses on available for sale securities transferred to held to maturity	2,690	3,448	6,285
Net unrealized holding (losses) gains arising during the period	(2,147)	0	0
Reclassification adjustment for net loss realized in net income on interest rate swaps used in cash flow hedges	(2,670)	0	0
Non-credit related unrealized losses on other-than-temporarily impaired debt securities	0	0	(680)
Unrecognized pension and postretirement income	7,144	(2,532)	(937)
Amortization of net unrecognized pension and postretirement income	1,156	1,020	1,025
Total Other Comprehensive Loss	$ (37,680)	65,228	$ 58,926
Accounting Standards Update 2019-04
Before-Tax Amount
Amortization of net unrealized losses on available for sale securities transferred to held to maturity		$ 3,700