Note 5 - Stock-based Compensation (Details Textual)	3 Months Ended
Mar. 31, 2020 USD ($) shares	Mar. 31, 2019 USD ($) shares
Number of Stock-based Compensation Plans in Effect	3
Share-based Payment Arrangement, Expense	$ 62,000	$ 25,000
Share-based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount, Total	$ 353,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross (in shares) \| shares	0	30,000

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
-SubTopic 10
-Section 50
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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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-Paragraph 1
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Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 10
-Section 50
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-URI http://asc.fasb.org/extlink&oid=120381028&loc=d3e5070-113901

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