Note 10 - Accrued Pension Liabilities - Components of Net Periodic Benefit Costs (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Components of net periodic benefit cost
Service cost	$ 4	$ 4	$ 5
Interest cost	14	17	17
Expected return on plan assets		(3)	(5)
Amortization of net loss	22	15	20
Net periodic benefit cost	$ 40	$ 33	$ 37