Note 5 - Fair Value of Financial Instruments (Tables)

6 Months Ended

Sep. 30, 2022

Notes Tables

Investments Classified by Contractual Maturity Date [Table Text Block]

Total		<1 Year		1–3 Years		3–7 Years
$	51,598,609	$	12,083,924	$	24,387,794	$	15,126,891

Fair Value, Assets Measured on Recurring Basis [Table Text Block]

	As of September 30, 2022						As of March 31, 2022
	Level 1		Level 2		Total		Level 1		Level 2		Total
Money market funds	$	1,757,277	$	-	$	1,757,277	$	6,756,993	$	-	$	6,756,993
Corporate bonds		-		49,841,332		49,841,332		-		45,153,894		45,153,894
Total	$	1,757,277	$	49,841,332	$	51,598,609	$	6,756,993	$	45,153,894	$	51,910,887

Schedule of Available-for-Sale Securities Reconciliation [Table Text Block]

	As of September 30, 2022									As of March 31, 2022
	Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value		Amortized Cost		Gross Unrealized Holding Gains		Gross Unrealized Holding Losses			Estimated Fair Value
Money market funds	$	1,757,277	$	-	$	-		$	1,757,277	$	6,756,993	$	-	$	-		$	6,756,993
Corporate bonds		52,125,043		-		(2,283,711	)		49,841,332		45,561,114		230,085		(637,305	)		45,153,894
Total	$	53,882,320	$	-	$	(2,283,711	)	$	51,598,609	$	52,318,107	$	230,085	$	(637,305	)	$	51,910,887

Debt Securities, Available-for-Sale, Unrealized Loss Position, Fair Value [Table Text Block]

	Less Than 12 Months					12 Months or Greater					Total
	Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses			Estimated Fair Value		Gross Unrealized Holding Losses
As of September 30, 2022
Corporate bonds	$	40,510,241	$	(1,327,302	)	$	9,331,091	$	(956,409	)	$	49,841,332	$	(2,283,711	)
Total	$	40,510,241	$	(1,327,302	)	$	9,331,091	$	(956,409	)	$	49,841,332	$	(2,283,711	)
As of March 31, 2022
Corporate bonds	$	6,306,750	$	(23,727	)	$	9,738,338	$	(613,578	)	$	16,045,088	$	(637,305	)
Total	$	6,306,750	$	(23,727	)	$	9,738,338	$	(613,578	)	$	16,045,088	$	(637,305	)