Retirement Plans - Other (Details) $ in Thousands	12 Months Ended
	Dec. 31, 2020 USD ($) item employee	Dec. 31, 2019 USD ($)
Projected benefit obligation:
Balance, beginning of the year	$ 2,637	$ 2,362
Service cost	116	88
Interest cost	76	90
Actuarial loss	422	291
Benefits paid to participants	(162)	(194)
Balance, end of year	3,089	2,637
Funded status of the plan
Excess of benefit obligation over the value of plan assets	(3,089)	(2,637)
Unrecognized net actuarial loss	957	575
Unrecognized prior service cost	20	28
Accrued benefit cost	(2,112)	(2,034)
Net amounts recognized in the consolidated balance sheets
Accrued benefit cost	(3,089)	(2,637)
Accumulated other comprehensive loss	977	603
Accrued benefit cost	(2,112)	$ (2,034)
Benefits expected to be paid in each of the next five years and thereafter
2021	260
2022	231
2023	156
2024	130
2025	145
2026 through 2030	897
Total	$ 1,819
Weighted-average rates used
Discount rate on the benefit obligation (as a percent)	2.00%	2.84%
Pension expense
Service cost	$ 116	$ 88
Interest cost	76	90
Amortization of prior service cost	8	8
Net loss amortization	40	6
Net periodic benefit cost	$ 240	$ 192
Minimum
Weighted-average rates used
Rate of employee compensation increase (as a percent)	1.75%	1.75%
Maximum
Weighted-average rates used
Rate of employee compensation increase (as a percent)	2.50%	2.50%
WAPA
Number of months to be in service for applicability of retirement plan	3 months
Number of weeks per year of service for one-time lump sum payment at retirement	14 days
Maximum number of retirees per year under the plan | employee	5
Number of retirees per year under the retirement plan | item	149
WAPA | Maximum
Number of weeks per year of service for one-time lump sum payment at retirement	315 days