Note 13 - Equity-based Compensation - Summary of Stock-based Compensation Expense Included in Results of Operations (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	$ 176	$ 106	$ 359	$ 343
Research and Development Expense [Member]
Stock-based compensation expense	8	12	22	36
Selling and Marketing Expense [Member]
Stock-based compensation expense	29	18	49	64
General and Administrative Expense [Member]
Stock-based compensation expense	$ 139	$ 76	$ 288	$ 243

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

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