Note 10 - Common Stock and Stock-based Compensation Plans - Equity-based Compensation Expense Included in Interim Condensed Consolidated Statements of Income (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Total equity-based compensation expense	$ 3,417	$ 2,679	$ 6,524	$ 5,095
Cost of Revenues [Member]
Total equity-based compensation expense	156	160	314	296
Research and Development, Net [Member]
Total equity-based compensation expense	1,722	1,458	3,345	2,820
Sales and Marketing [Member]
Total equity-based compensation expense	512	394	963	750
General and Administrative [Member]
Total equity-based compensation expense	$ 1,027	$ 667	$ 1,902	$ 1,229