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Note 8 - Investments, Including Investments Accounted for Using the Equity Method - Schedule of Investments (Details) - USD ($) | Mar. 31, 2019 | Dec. 31, 2018
--- | --- | ---
Short-term Investments | $ 9,162,641 | $ 6,251,064
Long-term investments | 32,692,006 | 32,381,686
Certificates of Deposit [Member] |  |
Short-term Investments | 1,189,539 | 1,378,666
Long-term investments |  | 317,178
US Treasury Securities [Member] |  |
Long-term investments | 3,530,646 | 2,902,004
U.S. Treasury Notes and Corporate Bonds [Member] |  |
Short-term Investments | 7,973,102 | 4,872,398
Preferred Stock [Member] |  |
Long-term investments | 104,019 | 104,019
Non-voting Common Units of LLC [Member] |  |
Long-term investments | 9,998,856 | 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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