Comprehensive Income (Loss), Net of Tax - Changes in Accumulated Other Comprehensive Income By Component (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	$ 301,728	$ 269,584	$ 249,603
Other comprehensive income (loss) before reclassifications	5,187	6,776	(5,287)
Amounts reclassified from accumulated other comprehensive income	354	677	322
Other Comprehensive Income (Loss)	5,541	7,453	(4,965)
Ending balance	334,392	301,728	269,584
Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance		0
Ending balance			0
Accumulated Other Comprehensive Income (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(6,357)	(13,810)	(8,514)
Other Comprehensive Income (Loss)	5,541	7,453	(4,965)
Ending balance	(816)	(6,357)	(13,810)
Accumulated Other Comprehensive Income (Loss) | Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(331)
Unrealized Gains and Losses on Available for Sale Securities
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	465	(3,697)	(1,250)
Other comprehensive income (loss) before reclassifications	5,306	4,162	(2,116)
Amounts reclassified from accumulated other comprehensive income	28	0	0
Other Comprehensive Income (Loss)	5,334	4,162	(2,116)
Ending balance	5,799	465	(3,697)
Unrealized Gains and Losses on Available for Sale Securities | Cumulative Effect, Period of Adoption, Adjustment
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance			(331)
Unrealized Gain on Cash Flow Swap
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	0	0
Other comprehensive income (loss) before reclassifications	485	0
Amounts reclassified from accumulated other comprehensive income		0
Other Comprehensive Income (Loss)	485	0
Ending balance	485	0	0
Net Actuarial Gain (Loss)
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(5,847)	(8,971)	(6,380)
Other comprehensive income (loss) before reclassifications	(251)	2,614	(2,833)
Amounts reclassified from accumulated other comprehensive income	169	510	242
Other Comprehensive Income (Loss)	(82)	3,124	(2,591)
Ending balance	(5,929)	(5,847)	(8,971)
Net Prior Service (Cost) Credit
AOCI Including Portion Attributable to Noncontrolling Interest, Net of Tax [Roll Forward]
Beginning balance	(975)	(1,142)	(884)
Other comprehensive income (loss) before reclassifications	(353)	0	(338)
Amounts reclassified from accumulated other comprehensive income	157	167	80
Other Comprehensive Income (Loss)	(196)	167	(258)
Ending balance	$ (1,171)	$ (975)	$ (1,142)