Note 5 - Fair Value of Financial Instruments - Assets Measured on Recurring Basis (Details) - USD ($)	Sep. 30, 2022	Mar. 31, 2022
Total	$ 51,598,609	$ 51,910,887
Money Market Funds [Member]
Total	1,757,277	6,756,993
Corporate Bond Securities [Member]
Total	49,841,332	45,153,894
Fair Value, Recurring [Member]
Total	51,598,609	51,910,887
Fair Value, Recurring [Member] | Money Market Funds [Member]
Total	1,757,277	6,756,993
Fair Value, Recurring [Member] | Corporate Bond Securities [Member]
Total	49,841,332	45,153,894
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Total	1,757,277	6,756,993
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Money Market Funds [Member]
Total	1,757,277	6,756,993
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member] | Corporate Bond Securities [Member]
Total	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Total	49,841,332	45,153,894
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Money Market Funds [Member]
Total	0	0
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member] | Corporate Bond Securities [Member]
Total	$ 49,841,332	$ 45,153,894