Note 5 - Stock-based Compensation - Compensation Cost (Details) - Selling, General and Administrative Expenses [Member] - USD ($) $ in Thousands	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Share-based compensation	$ 190	$ 158	$ 509	$ 436
Share-based Payment Arrangement, Option [Member]
Share-based compensation	151	102	372	233
Restricted Stock Units (RSUs) [Member]
Share-based compensation	$ 39	$ 56	$ 137	$ 203

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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-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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