Note 3 - Periodic Pension Expense - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Service cost - benefits earned during the period	$ 27	$ 16	$ 54	$ 32
Interest cost on projected benefit obligation	243	242	485	483
Expected return on plan assets	(430)	(305)	(859)	(609)
Recognized actuarial loss	283	270	566	547
Settlement loss		277		277
Net periodic pension cost	$ 123	$ 500	$ 246	$ 730