Note 4 - Periodic Pension Expense - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Service cost - benefits earned during the period	$ 38	$ 29	$ 114	$ 87
Interest cost on projected benefit obligation	216	271	648	813
Expected return on plan assets	(389)	(385)	(1,167)	(1,106)
Recognized actuarial loss	305	310	938	959
Settlement loss	82	280	413	616
Net periodic pension cost after settlements	$ 252	$ 505	$ 946	$ 1,369