Accumulated Other Comprehensive Income (Loss) - Components of Accumulated Other Comprehensive (Loss) Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	$ 612,227	$ 564,704	$ 528,119
Other comprehensive (loss) income	6,761	9,700	(3,099)
Ending Balance	622,322	612,227	564,704
Net Change in Unrealized Gains on Available for Sale Investment Securities
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	3,910	(6,229)	(2,861)
Other comprehensive (loss) income	7,044	10,139	(3,368)
Ending Balance	10,954	3,910	(6,229)
Net Change in Unfunded Pension Liability
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	(1,723)	(1,284)	(1,553)
Other comprehensive (loss) income	(283)	(439)	269
Ending Balance	(2,006)	(1,723)	(1,284)
Accumulated Other Comprehensive (Loss) Income
AOCI Attributable to Parent, Net of Tax [Roll Forward]
Beginning Balance	2,187	(7,513)	(4,414)
Other comprehensive (loss) income	6,761	9,700	(3,099)
Ending Balance	$ 8,948	$ 2,187	$ (7,513)