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Note 8 - Investments, Including Investments Accounted for Using the Equity Method - Schedule of Investments (Details) - USD ($) | Sep. 30, 2020 | Dec. 31, 2019
--- | --- | ---
Short-term Investments | $ 7,294,663 | $ 6,547,171
Long-term investments | 19,698,400 | 42,638,240
Certificates of Deposit [Member] |  |
Short-term Investments | 1,022,582 | 987,599
Long-term investments | 0 | 380,753
US Treasury Securities [Member] |  |
Long-term investments | 535,896 | 1,094,983
Corporate Bond Securities [Member] |  |
Short-term Investments | 852,000 | 910,000
U.S. Treasury Notes and Corporate Bonds [Member] |  |
Short-term Investments | 5,420,081 | 4,649,572
Preferred Stock [Member] |  |
Long-term investments | 104,019 | 104,019
Non-voting Preferred Units of DFH LLC [Member] |  |
Long-term investments | 0 | 12,000,000
Non-voting Common Units of LLC [Member] |  |
Long-term investments | 0 | 10,000,000
Voting Common Stock of Privately Held Company CB&T Holding Corporation [Member] |  |
Long-term investments | $ 19,058,485 | $ 19,058,485

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