Comprehensive Income (Loss) - Other Comprehensive Income (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Before-Tax Amount
Other comprehensive income (loss), before tax	$ (1,427)	$ 30	$ (3,901)	$ 8,201
Tax (Expense) Benefit
Other comprehensive income (loss), tax	366	(7)	998	(2,097)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	(1,096)	(58)	(3,015)	5,860
Reclassification from AOCI, current period	35	81	112	244
Other Comprehensive (Loss) Income	(1,061)	23	(2,903)	6,104
Unrealized Gains and Losses on Available for Sale Securities
Before-Tax Amount
OCI, before reclassifications	(1,719)	(397)	(5,333)	7,823
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	440	101	1,364	(2,000)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	(1,279)	(296)	(3,969)	5,823
Reclassification from AOCI, current period	0	0	0	0
Other Comprehensive (Loss) Income	(1,279)	(296)	(3,969)	5,823
Unrealized Loss on Cash Flow Swap
Before-Tax Amount
OCI, before reclassifications	245	317	1,281	48
Reclassification from AOCI, current period	(34)		(92)
Tax (Expense) Benefit
Other comprehensive income (loss) before reclassifications, tax	(62)	(79)	(327)	(11)
Reclassification from AOCI, current period	9		24
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	183	238	954	37
Reclassification from AOCI, current period	(25)	0	(68)	0
Other Comprehensive (Loss) Income	158	238	886	37
Amortization of Net Retirement Plan Actuarial Gain (Loss)
Before-Tax Amount
Reclassification from AOCI, current period	22	57	68	171
Tax (Expense) Benefit
Reclassification from AOCI, current period	(5)	(15)	(17)	(44)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	0	0	0	0
Reclassification from AOCI, current period	17	42	51	127
Other Comprehensive (Loss) Income	17	42	51	127
Amortization of Defined Benefit Pension, Prior-Service Costs
Before-Tax Amount
Reclassification from AOCI, current period	59	53	175	159
Tax (Expense) Benefit
Reclassification from AOCI, current period	(16)	(14)	(46)	(42)
Net-of-Tax Amount
Other comprehensive income (loss) before reclassifications	0	0	0	0
Reclassification from AOCI, current period	43	39	129	117
Other Comprehensive (Loss) Income	$ 43	$ 39	$ 129	$ 117