Note 8 - Net Income Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Net income used in the computation of basic and diluted net income per share (in thousands)	$ 2,781	$ 3,817	$ 5,157	$ 6,267
Weighted average shares outstanding - basic (in shares)	14,952,802	14,956,221	14,940,072	14,888,940
Common stock equivalents (in shares)	334,555	603,183	334,934	619,577
(Diluted) (in shares)	15,287,357	15,559,404	15,275,006	15,508,517
Net income (in dollars per share)	$ 0.19	$ 0.26	$ 0.35	$ 0.42
Net income (in dollars per share)	$ 0.18	$ 0.25	$ 0.34	$ 0.40