Note 4 - Investments (Details Textual) - Contingent Convertible Preferred Stock [Member] - USD ($)	Mar. 31, 2023	Dec. 31, 2022
Series A-1 and A-2, Preferred Stock [Member]
Equity Securities without Readily Determinable Fair Value, Amount	$ 4,100,000
Series E Preferred Stock [Member]
Equity Securities without Readily Determinable Fair Value, Amount	$ 995,000	$ 995,000

Amount of investment in equity security without readily determinable fair value.

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Topic 321
-SubTopic 10
-Name Accounting Standards Codification
-Section 50
-Paragraph 3
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org//1943274/2147479536/321-10-50-3

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