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Note 8 - Investments, Including Investments Accounted for Using the Equity Method - Schedule of Investments (Details) - USD ($) | Jun. 30, 2019 | Dec. 31, 2018
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Short-term Investments | $ 5,112,283 | $ 6,251,064
Long-term investments | 43,667,273 | 32,381,686
Certificates of Deposit [Member] |  |
Short-term Investments | 563,315 | 1,378,666
Long-term investments |  | 317,178
US Treasury Securities [Member] |  |
Long-term investments | 2,504,769 | 2,902,004
U.S. Treasury Notes and Corporate Bonds [Member] |  |
Short-term Investments | 4,548,968 | 4,872,398
Preferred Stock [Member] |  |
Long-term investments | 104,019 | 104,019
Non-voting Preferred Units of DFH LLC [Member] |  |
Long-term investments | 12,000,000 |
Non-voting Common Units of LLC [Member] |  |
Long-term investments | 10,000,000 | 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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