Net Periodic Pension Cost (Schedule of Net Benefit Costs) (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Retirement Plans
Interest cost	$ 67	$ 88	$ 135	$ 177
Amortization of net loss	44	35	87	70
Expected return on plan assets	(177)	(171)	(354)	(342)
Net periodic pension cost	(66)	(48)	(132)	(95)
Contributed amount	$ 0	$ 0	$ 0	$ 0