Note 12 - Pension and Other Postretirement Benefits - The Components of the Net Pension Expense for the Retirement Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Interest cost	$ 902	$ 889
Retirement Plan [Member]
Interest cost	902	889	$ 891
Amortization of unrecognized loss	809	1,112	759
Expected return on plan assets	(1,394)	(1,400)	(1,344)
Net pension expense	317	601	306
Current year actuarial (gain) loss	275	(237)	4,798
Amortization of actuarial loss	(809)	(1,112)	(759)
Total recognized in other comprehensive income	(534)	(1,349)	4,039
Total recognized in net pension cost (benefit) and other comprehensive income	$ (217)	$ (748)	$ 4,345