Note 3 - Fair Value of Financial Instruments - Reconciliation of Available-for-sale Securities (Details) - USD ($)	Mar. 31, 2022	Mar. 31, 2021
Amortized Cost	$ 52,318,107	$ 63,451,301
Gross Unrealized Holding Gains	230,085	1,570,195
Gross Unrealized Holding Losses	(637,305)	(160,674)
Estimated Fair Value	51,910,887	64,860,822
Money Market Funds [Member]
Amortized Cost	6,756,993	10,143,196
Gross Unrealized Holding Gains	0	0
Gross Unrealized Holding Losses	0	0
Estimated Fair Value	6,756,993	10,143,196
Corporate Bond Securities [Member]
Amortized Cost	45,561,114	53,308,105
Gross Unrealized Holding Gains	230,085	1,570,195
Gross Unrealized Holding Losses	(637,305)	(160,674)
Estimated Fair Value	$ 45,153,894	$ 54,717,626

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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Amount, before tax, of unrealized loss 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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