Note 7 - Stock-based Compensation - Non-cash Stock Compensation Expense (Details) - USD ($) $ in Thousands	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Stock-based comepensation expense	$ 943	$ 753
Share-based Payment Arrangement, Option [Member]
Stock-based comepensation expense	838	623
Restricted Stock [Member]
Stock-based comepensation expense	$ 105	$ 130

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

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