Note 8 - Benefit Plans - Net Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Service cost - benefits earned during the period	$ 117	$ 108	$ 65
Interest cost on projected benefit obligation	1,084	970	965
Expected return on plan assets	(1,491)	(1,717)	(1,218)
Recognized actuarial loss	1,259	1,132	1,042
Settlement loss	1,110		435
Net periodic pension cost after settlements	$ 2,079	$ 493	$ 1,289