Retirement Plans - Net Periodic Pension Cost (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 38	$ 48	$ 114	$ 144
Expected return on assets	(48)	(51)	(144)	(153)
Amortization of net loss	21	20	63	60
Net periodic pension cost	$ 11	$ 17	$ 33	$ 51