Note 3 - Fair Value of Financial Instruments (Tables)

12 Months Ended

Mar. 31, 2021

Notes Tables

Investments Classified by Contractual Maturity Date [Table Text Block]

Total		<1 Year		1 – 3 Years		3 – 5 Years
$	64,860,822	$	17,822,153	$	36,716,130	$	10,322,539

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

	As of March 31, 2021						As of March 31, 2020
	Level 1		Level 2		Total		Level 1		Level 2		Total
Money market funds	$	10,143,196	$	-	$	10,143,196	$	7,903,433	$	-	$	7,903,433
Corporate bonds		-		54,717,626		54,717,626		-		62,691,309		62,691,309
Total	$	10,143,196	$	54,717,626	$	64,860,822	$	7,903,433	$	62,691,309	$	70,594,742

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

	As of March 31, 2021									As of March 31, 2020
	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	$	10,143,196	$	-	$	-		$	10,143,196	$	7,903,433	$	-	$	-		$	7,903,433
Corporate bonds		53,308,105		1,570,195		(160,674	)		54,717,626		62,030,120		752,621		(91,432	)		62,691,309
Total	$	63,451,301	$	1,570,195	$	(160,674	)	$	64,860,822	$	69,933,553	$	752,621	$	(91,432	)	$	70,594,742

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 March 31, 2021
Corporate bonds	$	10,322,539	$	(160,674	)	$	-	$	-	$	10,322,539	$	(160,674	)
Total	$	10,322,539	$	(160,674	)	$	-	$	-	$	10,322,539	$	(160,674	)
As of March 31, 2020
Corporate bonds	$	19,525,169	$	(91,432	)	$	-	$	-	$	19,525,169	$	(91,432	)
Total	$	19,525,169	$	(91,432	)	$	-	$	-	$	19,525,169	$	(91,432	)