Note 8 - Share-based Compensation - Stock Compensation Expense (Details) - USD ($) $ in Thousands	3 Months Ended	6 Months Ended
Jun. 30, 2021	Jun. 30, 2020	Jun. 30, 2021	Jun. 30, 2020
Stock compensation expense	$ 2,520	$ 1,145	$ 4,024	$ 2,258
Research and Development Expense [Member]
Stock compensation expense	437	222	620	397
Selling and Marketing Expense [Member]
Stock compensation expense	269	96	453	325
General and Administrative Expense [Member]
Stock compensation expense	1,667	699	2,646	1,275
Cost of Sales [Member]
Stock compensation expense	$ 147	$ 128	$ 305	$ 261

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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