Note 10 - Defined Benefit Retirement Plan (Details Textual) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($)	Mar. 31, 2016 USD ($)
Defined Benefit Plan, Number of Employees Covered	3
Defined Benefit Plan, Number of Present Employees Covered	2
Defined Benefit Plan, Number of Retired Employees Covered	1
Deferred Compensation Arrangement with Individual, Requisite Service Period	25 years
Defined Benefit Plan, Number of Current Officers Fully Vested	1
Defined Benefit Plan, Number of Current Officers That Will Be Fully Vested in Year 2017	1
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 34	$ 33