Note 5 - Fair Value of Financial Instruments - Reconciliation of Available-for-sale Securities (Details) - USD ($)	Sep. 30, 2022	Mar. 31, 2022
Amortized Cost	$ 53,882,320	$ 52,318,107
Gross Unrealized Holding Gains	0	230,085
Gross Unrealized Holding Losses	(2,283,711)	(637,305)
Estimated Fair Value	51,598,609	51,910,887
Money Market Funds [Member]
Amortized Cost	1,757,277	6,756,993
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	1,757,277	6,756,993
Corporate Bond Securities [Member]
Amortized Cost	52,125,043	45,561,114
Gross Unrealized Holding Gains	0	230,085
Gross Unrealized Holding Losses	(2,283,711)	(637,305)
Estimated Fair Value	$ 49,841,332	$ 45,153,894

Amount, before tax, of unrealized gain in accumulated other comprehensive income (AOCI) on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

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