Note 5 - Fair Value of Financial Instruments (Tables)

6 Months Ended

Sep. 30, 2020

Notes Tables

Investments Classified by Contractual Maturity Date [Table Text Block]

Total		<1 Year		1–3 Years		3–5 Years
$	67,555,355	$	26,778,033	$	34,271,054	$	6,506,268

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

	As of September 30, 2020						As of March 31, 2020
	Level 1		Level 2		Total		Level 1		Level 2		Total
Money market funds	$	3,546,052	$	-	$	3,546,052	$	7,903,433	$	-	$	7,903,433
Corporate bonds		-		64,009,303		64,009,303		-		62,691,309		62,691,309
Total	$	3,546,052	$	64,009,303	$	67,555,355	$	7,903,433	$	62,691,309	$	70,594,742

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

	As of September 30, 2020								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	$	3,546,052	$	-	$	-	$	3,546,052	$	7,903,433	$	-	$	-		$	7,903,433
Corporate bonds		61,924,230		2,085,073		-		64,009,303		62,030,120		752,621		(91,432	)		62,691,309
Total	$	65,470,282	$	2,085,073	$	-	$	67,555,355	$	69,933,553	$	752,621	$	(91,432	)	$	70,594,742