Note 8 - Accrued Retirement Benefits - Net Periodic Cost (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Interest cost	$ 527	$ 495	$ 1,580	$ 1,485
Expected return on plan assets	(480)	(578)	(1,446)	(1,734)
Amortization of net loss	211	185	634	555
Pension and other postretirement expenses	$ 258	$ 102	$ 768	$ 306