Supplemental Cash Flow Disclosures (Details) - USD ($) $ in Thousands		3 Months Ended		9 Months Ended
	Jan. 01, 2019	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Cash paid during the period for:
Interest				$ 1,814	$ 3,012
Income taxes				2,380	4,890
Noncash investing activities:
Unrealized gain on unrecognized post retirement costs		$ 20	$ 14	60	42
Unrealized gain on available for sale securities		334	(246)	1,161	317
Unrealized loss on junior subordinated debentures		$ (326)	$ (501)	(779)	(1,748)
Cash dividend declared				1,867	$ 1,865
Adoption of ASU 2016-02: recognition of lease right-of-use (ROU) asset	$ 3,395			$ 0
Adoption of ASU 2016-02: recognition of lease liability	$ 3,486
Accounting standards update	us-gaap:AccountingStandardsUpdate201602Member