Pension and Retirement Plans - Schedule of Projected Benefit Obligations and Funded Status (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018
Pension Plan
Change in projected benefit obligation
Obligation at beginning of year	$ 40,522,000	$ 43,943,000
Interest cost	1,680,000	1,557,000
Actuarial loss/(gain)	4,670,000	(3,659,000)
Benefits paid	(1,471,000)	(1,319,000)
Obligation at end of year	45,401,000	40,522,000
Change in plan assets
Fair value at beginning of year	42,648,000	45,247,000
Actual return on plan assets	8,954,000	(1,280,000)
Employer contribution	0
Benefits paid	(1,471,000)	(1,319,000)
Fair value at end of year	50,131,000	42,648,000
Funded (underfunded) status at end of year	4,730,000	2,126,000
Supplemental Retirement Plan
Change in projected benefit obligation
Obligation at beginning of year	8,830,000	9,204,000
Service cost	283,000	354,000
Interest cost	349,000	309,000
Actuarial loss/(gain)	770,000	(499,000)
Benefits paid	(610,000)	(538,000)
Obligation at end of year	9,622,000	8,830,000
Change in plan assets
Employer contribution	610,000	538,000
Benefits paid	(610,000)	(538,000)
Funded (underfunded) status at end of year	(9,622,000)	(8,830,000)
Postretirement Healthcare Plan
Change in projected benefit obligation
Obligation at beginning of year	598,000	617,000
Service cost	25,000	23,000
Interest cost	25,000	22,000
Actuarial loss/(gain)	76,000	(30,000)
Benefits paid	(35,000)	(34,000)
Obligation at end of year	689,000	598,000
Change in plan assets
Employer contribution	35,000	33,000
Benefits paid	(35,000)	(33,000)
Funded (underfunded) status at end of year	$ (689,000)	$ (598,000)