Note 6 - Share-based Compensation - Compensation Cost (Details) - Selling, General and Administrative Expenses [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020
Share-based compensation	$ 650	$ 239	$ 1,771	$ 1,338
Common Stock [Member]
Share-based compensation	100	100	300	300
Employee and Nonemployee Stock Option [Member]
Share-based compensation	52	59	157	173
Restricted Stock Units (RSUs) [Member]
Share-based compensation	$ 498	$ 80	$ 1,314	$ 865

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
-Topic 718
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Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
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