Comprehensive Income - Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Before-Tax Amount
Other comprehensive income (loss), before tax	$ (3,062)	$ 5,300
Tax (Expense) Benefit
Other comprehensive income (loss), tax	782	(1,355)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	(2,337)	3,879
Reclassification from AOCI, current period	57	66
Other Comprehensive (Loss) Income	(2,280)	3,945
Unrealized Gains and Losses on Available for Sale Securities
Before-Tax Amount
OCI, before reclassifications	(5,121)	5,504
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	1,309	(1,406)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	(3,812)	4,098
Reclassification from AOCI, current period	0	0
Other Comprehensive (Loss) Income	(3,812)	4,098
Unrealized Loss on Cash Flow Swap
Before-Tax Amount
OCI, before reclassifications	1,982	(294)
Reclassification from AOCI, current period	(28)
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	(507)	75
Reclassification from AOCI, current period	8
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	1,475	(219)
Reclassification from AOCI, current period	(20)	0
Other Comprehensive (Loss) Income	1,455	(219)
Amortization of Net Retirement Plan Actuarial Gain (Loss)
Before-Tax Amount
Reclassification from AOCI, current period	46	36
Tax (Expense) Benefit
Reclassification from AOCI, current period	(12)	(9)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	0	0
Reclassification from AOCI, current period	34	27
Other Comprehensive (Loss) Income	34	27
Amortization of Defined Benefit Pension, Prior-Service Costs
Before-Tax Amount
Reclassification from AOCI, current period	59	54
Tax (Expense) Benefit
Reclassification from AOCI, current period	(16)	(15)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	0	0
Reclassification from AOCI, current period	43	39
Other Comprehensive (Loss) Income	$ 43	$ 39

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