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	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Total equity-based compensation expense	$ 3,546	$ 2,752	$ 10,070	$ 7,847
Cost of Revenues [Member]
Total equity-based compensation expense	159	168	473	464
Research and Development, Net [Member]
Total equity-based compensation expense	1,770	1,494	5,115	4,314
Sales and Marketing [Member]
Total equity-based compensation expense	533	362	1,496	1,112
General and Administrative [Member]
Total equity-based compensation expense	$ 1,084	$ 728	$ 2,986	$ 1,957