Note 12 - Defined Benefit Retirement Plan (Details Textual) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)
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			3
Defined Benefit Plan, Net Periodic Benefit Cost (Credit)	$ 34	$ 33	$ 103	$ 100