Reconciliation of changes in the components of OCI (Details) - USD ($) $ in Thousands		12 Months Ended
		Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax		$ (5,704)	$ 26,588	$ 12,017
Other Comprehensive Income (Loss), Available-for-sale Securities, Tax, Portion Attributable to Parent		7,073	(2,829)	(3,172)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification and Tax		(7,938)	36,994	16,725
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax		2,234	(10,406)	(4,708)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax		18,691	14,306	2,346
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax		(5,256)	(4,023)	(660)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Loss on Termination of Derivatives, After Tax			(492)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Loss on Termination of Derivatives, Tax			192
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Loss on Termination of Derivatives, before Tax		0	(684)
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), before Tax			176
Other Comprehensive Income (Loss), Defined Benefit Plan, Settlement and Curtailment Gain (Loss), after Tax			126
Other Comprehensive Income (Loss), Defined Benefit Plan, Adjustment for Settlement or Curtailment Gain (Loss), Tax			(50)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax		7,490	(6,575)	(4,048)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	[1]	(1,388)	1,223	521
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax		13,435	10,283	1,686
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax		7,490	(6,575)	(4,048)
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax		(19,139)	16,797	10,331
Other Comprehensive Income (Loss), before Tax [Abstract]
Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax		(26,629)	23,372	14,379
Change in fair value of securities available for sale, pre tax amount		29,995	(11,686)	(12,055)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax		3,414	(5,785)	(2,123)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax		1,331	982	(8)
Amortization of certain costs included in net periodic retirement costs, pre tax amount		(192)	(276)	(276)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax	[1]	4,937	(4,351)	(1,855)
Total other comprehensive loss, pre tax amount		(51,687)	30,707	26,041
Other Comprehensive Income (Loss), Tax [Abstract]
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, Tax		7,073	(2,829)	(2,761)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax		(960)	1,627	597
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax		(374)	(276)	2
Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax		(54)	(78)	(78)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax	[1]	(1,388)	1,223	521
Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent		13,175	(8,181)	(6,699)
Other Comprehensive Income (Loss), Net of Tax [Abstract]
Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax		(22,922)	8,857	9,294
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax, Portion Attributable to Parent		(22,922)	8,857	10,345
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax		2,454	(4,158)	(1,526)
Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax		957	706	(6)
Amortization of certain costs included in net periodic retirement costs, after tax amount		138	198	198
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax	[1]	3,549	(3,128)	(1,334)
Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent		(38,512)	22,526	19,342
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax		0	0	(1,462)
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Tax		0	0	411
Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, Net of Tax		0	0	(1,051)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, before Tax, Portion Attributable to Parent		$ (29,995)	$ 11,686	$ 13,517

[1] The amortization of prior service costs is included in the computation of net periodic pension costs as disclosed in Note 14 - Employee Benefit Plans within the Notes to the Consolidated Financial Statements in Item 8.