Note 8 - Accrued Retirement Benefits - Net Periodic Cost (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Interest cost	$ 495	$ 557
Expected return on plan assets	(578)	(562)
Amortization of net loss	185	207
Pension and other postretirement expenses	$ 102	$ 202