Employee Benefit Plans (Details) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019	Dec. 31, 2020
Pension Benefits
Components of net periodic benefit costs:
Interest cost	$ 94,000	$ 109,000
Expected return on plan assets	(200,000)	(195,000)
Amortization of net loss	30,000	19,000
Settlement charge	368,000	0
Net periodic benefit/cost	$ 292,000	(67,000)
Defined Benefit Plan, Benefit Obligation				$ 12,668,000
Defined Benefit Plan, Plan Assets, Amount				11,865,000
Defined Benefit Plan, Funded (Unfunded) Status of Plan				$ (803,000)
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate	2.65%		3.12%
Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-term Rate of Return on Plan Assets	7.50%		7.50%
Defined Benefit Plan, Benefit Obligation, (Increase) Decrease for Settlement	$ (650,000)
Defined Benefit Plan, Plan Assets, Payment for Settlement	368,000	0
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	(368,000)		$ 5,068,000
Postretirement Benefits
Components of net periodic benefit costs:
Interest cost	1,000	1,000
Amortization of net loss	(2,000)	(2,000)
Net periodic benefit/cost	$ (1,000)	$ (1,000)
Postretirement Benefits | Employees Hired before January 1, 2003
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Benefit based on highest average salary for number of consecutive years	5 years
Number of years for consecutive years calculation	10 years
Postretirement Benefits | Employees Hired on or after January 1, 2003
Defined Benefit Plans and Other Postretirement Benefit Plans [Line Items]
Percent of annual salary to calculate benefit	2.00%
Before Settlement | Pension Benefits
Components of net periodic benefit costs:
Defined Benefit Plan, Benefit Obligation	$ 13,734,000
Defined Benefit Plan, Plan Assets, Amount	10,253,000
Defined Benefit Plan, Funded (Unfunded) Status of Plan	(3,481,000)
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	7,823,000
After Settlement
Components of net periodic benefit costs:
Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax	7,455,000
After Settlement | Pension Benefits
Components of net periodic benefit costs:
Defined Benefit Plan, Benefit Obligation	13,084,000
Defined Benefit Plan, Plan Assets, Amount	9,603,000
Defined Benefit Plan, Funded (Unfunded) Status of Plan	$ (3,481,000)
Retirement prior to January 1, 1993 [Member]
Components of net periodic benefit costs:
Percent of healthcare costs paid	100.00%