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Note 9 - Fair Value - Fair Values for Investments (Details) - USD ($)	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018	Dec. 31, 2018
Marketable equity securities, cost	$ 5,521,241
Marketable equity securities	5,477,223
Marketable equity securities, realized gain (loss)	120,584
Marketable equity securities	(44,018)
Securities available for sale, realized gain (loss)
Securities available for sale, gain (loss)	(32,087)
Realized gain (loss)	120,584
Gain (loss)	(76,105)	$ (93,003)
Reported Value Measurement [Member]
Marketable equity securities, cost	5,477,223
U.S. Treasury notes, Fair Value	87,513,353
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Marketable equity securities	5,477,223
U.S. Treasury notes, Fair Value	$ 87,513,353