Note 11 - 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				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Net income	$ 8,299	$ 5,929	$ 3,500	$ 3,174	$ 14,228	$ 6,674
Weighted average shares outstanding (in shares)	20,611		20,180		20,579	20,174
Basic earnings per share (in dollars per share)	$ 0.40		$ 0.17		$ 0.69	$ 0.33
Common stock equivalents, if dilutive (in shares)	348		219		321	241
Shares used in computing diluted earnings per common share (in shares)	20,959		20,399		20,900	20,415
Diluted earnings per share (in dollars per share)	$ 0.40		$ 0.17		$ 0.68	$ 0.33
Shares excluded in computing diluted earnings per share as those shares would be anti-dilutive (in shares)	0		713		152	651