Note 2 - Fair Value Measurements - Financial Instruments Measured at Fair Value on a Recurring Basis (Details) - Fair Value, Recurring [Member] - USD ($)	Sep. 30, 2021	Dec. 31, 2020
Investments, fair value	$ 5,853,012	$ 3,609,533
Publicly Traded Common Stock [Member]
Investments, fair value	845,820	979,020
Publicly Traded Options [Member]
Investments, fair value	46,848	55,848
Private Company Common Stock [Member]
Investments, fair value	178,824
Private Company Preferred Stock [Member]
Investments, fair value	4,781,520	2,574,665
Fair Value, Inputs, Level 1 [Member]
Investments, fair value	892,668	1,034,868
Fair Value, Inputs, Level 1 [Member] | Publicly Traded Common Stock [Member]
Investments, fair value	845,820	979,020
Fair Value, Inputs, Level 1 [Member] | Publicly Traded Options [Member]
Investments, fair value	46,848	55,848
Fair Value, Inputs, Level 3 [Member]
Investments, fair value	4,960,344	2,574,665
Fair Value, Inputs, Level 3 [Member] | Private Company Common Stock [Member]
Investments, fair value	178,824
Fair Value, Inputs, Level 3 [Member] | Private Company Preferred Stock [Member]
Investments, fair value	$ 4,781,520	$ 2,574,665