Retirement Plans - Reconciliation of Changes in Plan's Projected Benefit Obligations and Assets (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Change in benefit obligation:
Projected benefit obligation at beginning of year	$ 5,944	$ 6,579
Interest cost	242	224	$ 253
Actuarial loss (gain)	510	(362)
Expenses paid	0	(135)
Benefits paid	(357)	(362)
Projected benefit obligation at end of year	6,339	5,944	6,579
Change in plan assets:
Fair value of plan assets at beginning of year	4,737	5,261
Actual return on plan assets	972	(27)
Company contributions	31	0
Benefits paid	(357)	(362)
Fair value of plan assets at end of year	5,383	4,737	$ 5,261
Funded status	$ (956)	$ (1,207)