Retirement Plans - Net Periodic Pension Cost (Details) - Pension Plans, Defined Benefit [Member] - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Defined Benefit Plan Disclosure [Line Items]
Interest cost	$ 48	$ 60
Expected return on assets	(51)	(46)
Amortization of net loss	20	24
Net periodic pension cost	$ 17	$ 38