Retirement Plans - Net Periodic Pension Cost (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 48	$ 60	$ 144	$ 180
Expected return on assets	(51)	(46)	(153)	(138)
Amortization of net loss	20	24	60	72
Net periodic pension cost	$ 17	$ 38	$ 51	$ 114