Note 3 - Basis of Presentation and Summary of Significant Accounting Policies (Details Textual) - USD ($)	12 Months Ended
Dec. 31, 2020	Dec. 31, 2019
Indefinite-lived Intangible Assets (Excluding Goodwill), Ending Balance	$ 8,639,000	$ 8,639,000
Share-based Payment Arrangement, Option [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term (Year)	10 years
In-Process Research and Development Asset [Member]
Indefinite-lived Intangible Assets (Excluding Goodwill), Ending Balance	$ 8,600,000	8,600,000
Impairment of Intangible Assets, Indefinite-lived (Excluding Goodwill)	$ 0	$ 0
Minimum [Member]
Property, Plant and Equipment, Useful Life (Year)	2 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term (Year)	5 years 113 days	5 years 91 days
Maximum [Member]
Property, Plant and Equipment, Useful Life (Year)	15 years
Share-based Compensation Arrangement by Share-based Payment Award, Fair Value Assumptions, Expected Term (Year)	10 years	5 years 281 days

Amount of impairment loss resulting from write-down of assets, excluding financial assets and goodwill, lacking physical substance and having a projected indefinite period of benefit to fair value.

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=66006027&loc=d3e16373-109275

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 28
-Subparagraph (b)
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