Pension and Other Postretirement Benefits - The Components of the Net Pension Expense (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Employee Pension Plan [Member]
Interest cost	$ 128	$ 163	$ 384	$ 489
Amortization of actuarial (gain) loss	122	111	366	333
Expected return on plan assets	(274)	(257)	(822)	(771)
Net pension (benefit) expense	(24)	17	(72)	51
Directors' Plan [Member]
Service cost	4	4	12	11
Interest cost	12	16	36	48
Amortization of actuarial (gain) loss	(5)	(14)	(15)	(41)
Amortization of past service credit	0	0	0	0
Net pension (benefit) expense	11	6	33	18
Other Post Retirement Benefit Plan Defined Benefit [Member]
Service cost	73	69	219	206
Interest cost	58	64	174	194
Amortization of actuarial (gain) loss	8		24
Amortization of past service credit	(21)	(21)	(63)	(64)
Net pension (benefit) expense	$ 118	$ 112	$ 354	$ 336