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Note 9 - Fair Value - Fair Values for Investments (Details) - USD ($)	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Dec. 31, 2018
Marketable equity securities, cost	$ 11,934,888		$ 11,934,888
Marketable equity securities	12,022,361		12,022,361
Marketable equity securities, realized gain (loss)			415,572
Marketable equity securities			87,473
Securities available for sale, realized gain (loss)			4,276
Securities available for sale, gain (loss)			(36,957)
Realized gain (loss)			419,848
Gain (loss)	126,621	$ 206,306	50,516	$ 113,303
Reported Value Measurement [Member]
Marketable equity securities, cost	12,022,361		12,022,361
Securities available for sale, cost	85,019,145		85,019,145
Estimate of Fair Value Measurement [Member] \| Fair Value, Inputs, Level 1 [Member]
Marketable equity securities	12,022,361		12,022,361
Securities available for sale, cost	$ 85,019,145		$ 85,019,145