Net Periodic Pension Cost (Schedule of Net Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Retirement Plans
Interest cost	$ 68	$ 89
Amortization of net loss	43	35
Expected return on plan assets	(177)	(171)
Net periodic pension cost	(66)	(47)
Contributed amount	$ 0	$ 0