Note 4 - Periodic Pension Expense - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Service cost - benefits earned during the period	$ 46	$ 38	$ 92	$ 76
Pension plan termination charge	6,945	0	6,945	0
Pension Plan [Member]
Interest cost on projected benefit obligation	153	216	340	432
Expected return on plan assets	(239)	(389)	(597)	(778)
Recognized actuarial loss	526	313	1,126	633
Settlement loss	0	193	0	331
Net periodic pension cost after settlements	$ 7,431	$ 371	$ 7,906	$ 694