Note 1 - Organization and Significant Accounting Policies - Equity-based Compensation Expenses Related to Stock Options, SARs, RSUs and Employee Stock Purchase Plan (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Total equity-based compensation expense	$ 13,636	$ 10,718	$ 10,367
Cost of Sales [Member]
Total equity-based compensation expense	639	630	588
Research and Development Expense [Member]
Total equity-based compensation expense	6,874	5,857	5,141
Sales and Marketing [Member]
Total equity-based compensation expense	2,038	1,495	1,587
General and Administrative Expense [Member]
Total equity-based compensation expense	$ 4,085	$ 2,736	$ 3,051