Comprehensive Income (Loss) - Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Before-Tax Amount
Other comprehensive income (loss), before tax	$ 588	$ 2,871	$ (2,474)	$ 8,171
Tax (Expense) Benefit
Other comprehensive income (loss), tax	(150)	(735)	632	(2,090)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	418	2,039	(1,919)	5,918
Reclassification from AOCI, current period	20	97	77	163
Other Comprehensive Income (Loss)	438	2,136	(1,842)	6,081
Unrealized Gains and Losses on Available for Sale Securities
Before-Tax Amount
OCI, before reclassifications	1,507	2,716	(3,614)	8,220
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	(385)	(695)	924	(2,101)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	1,122	2,021	(2,690)	6,119
Reclassification from AOCI, current period	0	0	0	0
Other Comprehensive Income (Loss)	1,122	2,021	(2,690)	6,119
Unrealized Loss on Cash Flow Swap
Before-Tax Amount
OCI, before reclassifications	(946)	25	1,036	(269)
Reclassification from AOCI, current period	(30)		(58)
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	242	(7)	(265)	68
Reclassification from AOCI, current period	7		15
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	(704)	18	771	(201)
Reclassification from AOCI, current period	(23)	0	(43)	0
Other Comprehensive Income (Loss)	(727)	18	728	(201)
Amortization of Net Retirement Plan Actuarial Gain (Loss)
Before-Tax Amount
Reclassification from AOCI, current period	0	78	46	114
Tax (Expense) Benefit
Reclassification from AOCI, current period	0	(20)	(12)	(29)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	0	0	0	0
Reclassification from AOCI, current period	0	58	34	85
Other Comprehensive Income (Loss)	0	58	34	85
Amortization of Defined Benefit Pension, Prior-Service Costs
Before-Tax Amount
Reclassification from AOCI, current period	57	52	116	106
Tax (Expense) Benefit
Reclassification from AOCI, current period	(14)	(13)	(30)	(28)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	0	0	0	0
Reclassification from AOCI, current period	43	39	86	78
Other Comprehensive Income (Loss)	$ 43	$ 39	$ 86	$ 78

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