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
	Mar. 31, 2020	Mar. 31, 2019
Total equity-based compensation expense	$ 3,107	$ 2,416
Cost of Revenues [Member]
Total equity-based compensation expense	158	136
Research and Development, Net [Member]
Total equity-based compensation expense	1,623	1,362
Sales and Marketing [Member]
Total equity-based compensation expense	451	356
General and Administrative [Member]
Total equity-based compensation expense	$ 875	$ 562