Note 9 - Earnings Per Share - Reconciliation of Basic and Diluted Earnings Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Net income used in the computation of basic and diluted net income per share (in thousands)	$ 9,944	$ 3,921	$ 28,485	$ 9,078
Weighted average shares outstanding - basic (in shares)	15,084,300	14,947,552	15,041,738	14,942,565
Dilutive common stock equivalents (in shares)	626,822	319,298	319,297	329,722
Weighted average number of shares outstanding during the period, diluted (in shares)	15,711,122	15,266,850	15,361,035	15,272,287
Basic (in dollars per share)	$ 0.66	$ 0.26	$ 1.89	$ 0.61
Diluted (in dollars per share)	$ 0.63	$ 0.26	$ 1.85	$ 0.59