Note 12 - Equity Incentive Plan - Total Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Stock-based compensation expense	$ 1,920	$ 1,311	$ 3,954	$ 4,140
Cost of Sales [Member]
Stock-based compensation expense	202	114	564	288
Research and Development Expense [Member]
Stock-based compensation expense	206	50	558	318
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense	$ 1,512	$ 1,147	$ 2,832	$ 3,534

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

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