Note 10 - Net Income per Share - Computation of Basic and Diluted Net Income per Share (Details) - USD ($) $ / shares in Units, shares in Thousands, $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Basic:
Net income	$ 3,174	$ 3,513
Weighted average shares outstanding (in shares)	20,168	19,640
Basic earnings per share (in dollars per share)	$ 0.16	$ 0.18
Diluted:
Net income	$ 3,174	$ 3,513
Weighted average shares outstanding (in shares)	20,168	19,640
Common stock equivalents, if dilutive (in shares)	270	565
Shares used in computing diluted earnings per common share (in shares)	20,438	20,205
Diluted earnings per share (in dollars per share)	$ 0.16	$ 0.17
Shares excluded in computing diluted earnings per share as those shares would be anti-dilutive (in shares)	468	542