Note 4 - Periodic Pension Expense - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Service cost - benefits earned during the period	$ 38	$ 29	$ 76	$ 58
Interest cost on projected benefit obligation	216	271	432	542
Expected return on plan assets	(389)	(384)	(778)	(721)
Recognized actuarial loss	313	324	633	649
Settlement loss	193	336	331	336
Net periodic pension cost after settlements	$ 371	$ 576	$ 694	$ 864