Note 11 - Retirement Plans - Net Periodic Benefit Cost (Details) - Supplemental Employee Retirement Plan [Member] - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Service cost	$ 19	$ 15
Interest cost	24	19
Recognized net actuarial loss	5
Net periodic benefit cost	$ 48	$ 34
Discount rate used to determine net period benefit cost	3.39%	3.22%
Discount rate used to determine benefit obligation at year end	3.31%	3.39%
Rate of compensation increase	4.00%	4.00%