Note 13 - Defined Benefit Plan (Details Textual)	3 Months Ended
	Mar. 31, 2019
Defined Benefit Plan, Number of Employees Covered	3
Defined Benefit Plan, Number of Present Employees Covered	1
Defined Benefit Plan, Number of Retired Employees Covered	2
Deferred Compensation Arrangement with Individual, Requisite Service Period	25 years