Note 10 - Net Income Per Common Share - Calculation of Diluted Shares (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Net income attributable to common stockholders	$ 9,316	$ 1,151	$ 10,581	$ 2,094
Basic shares used to compute earnings per share (in shares)	19,735,364	17,273,412	19,071,722	15,529,026
Effect of dilutive securities (in shares)	5,607,748	6,383,221	5,633,702	5,522,193
Weighted average diluted shares (in shares)	25,343,112	23,656,633	24,705,424	21,051,219
Basic net income per common share (in dollars per share)	$ 0.47	$ 0.07	$ 0.55	$ 0.13
Diluted net income per common share (in dollars per share)	$ 0.37	$ 0.05	$ 0.43	$ 0.10