Note 1 - Summary of Significant Accounting Policies (Details Textual) - USD ($)  | 
Mar. 31, 2021  | 
Dec. 31, 2020  | 
|---|---|---|
| Notes Payable, Fair Value Disclosure | $ 191,000 | $ 745,000 | 
| X | ||||||||||
- Definition Fair value portion of notes payable. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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