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Note 8 - Investments, Including Investments Accounted for Using the Equity Method - Schedule of Investments (Details) - USD ($) | Dec. 31, 2018 | Dec. 31, 2017
--- | --- | ---
Short-term Investments | $ 6,251,064 | $ 1,659,299
Long-term investments | 32,381,686 | 13,901,281
Certificates of Deposit [Member] |  |
Short-term Investments | 1,378,666 | 746,219
Long-term investments | 317,178 | 1,080,426
US Treasury Securities [Member] |  |
Long-term investments | 2,902,004 | 2,820,855
U.S. Treasury Notes and Corporate Bonds [Member] |  |
Short-term Investments | 4,872,398 | 809,184
Convertible Debt Securities [Member] |  |
Short-term Investments |  | 103,896
Preferred Stock [Member] |  |
Long-term investments | 104,019 |
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 |

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