Note 11 - Equity Incentive Plan - Total Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Stock-based compensation expense	$ 2,863	$ 1,920	$ 7,919	$ 3,954
Cost of Sales [Member]
Stock-based compensation expense	142	202	485	564
Research and Development Expense [Member]
Stock-based compensation expense	360	206	1,003	558
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense	$ 2,361	$ 1,512	$ 6,431	$ 2,832

Amount of expense for award under share-based payment arrangement. Excludes amount capitalized.

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