Note 9 - Net Income (Loss) Per Common Share - Calculation of Diluted Shares (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 attributable to common stockholders	$ 838	$ 1,046	$ 1,265	$ 943
Basic shares used to compute earnings per share (in shares)	18,819,459	15,180,169	18,734,401	14,642,378
Effect of dilutive securities (in shares)	5,719,840	5,194,189	5,705,558	4,421,217
Weighted average diluted shares (in shares)	24,539,299	20,374,358	24,439,959	19,063,595
Basic net income per common share (in dollars per share)	$ 0.04	$ 0.07	$ 0.07	$ 0.06
Diluted net income per common share (in dollars per share)	$ 0.03	$ 0.05	$ 0.05	$ 0.05