Note 4 - Periodic Pension Expense - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Service cost - benefits earned during the period	$ 46	$ 38
Pension Plan [Member]
Interest cost on projected benefit obligation	187	216
Expected return on plan assets	(358)	(389)
Recognized actuarial loss	600	320
Settlement loss	0	138
Net periodic pension cost after settlements	$ 475	$ 323