Note 12 - Stock-based Compensation - Stock-based Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Stock-based compensation expense	$ 5,057	$ 5,168	$ 4,294
Cost of Sales [Member]
Stock-based compensation expense	260	358	324
Research and Development Expense [Member]
Stock-based compensation expense	920	1,970	1,901
Selling, General and Administrative Expenses [Member]
Stock-based compensation expense	$ 3,877	$ 2,840	$ 2,069

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

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