Note 4 - Marketable Securities (Tables)

12 Months Ended

Mar. 31, 2018

Notes Tables

Marketable Securities [Table Text Block]

Total		<1 Year		1–3 Years		3–5 Years
$	73,603,967	$	20,765,809	$	31,124,052	$	21,714,106

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

	As of March 31, 2018									As of March 31, 2017
	Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value		Adjusted Cost		Gross Unrealized Gains		Gross Unrealized Losses			Fair Market Value
Corporate bonds	$	74,853,327	$	-	$	(1,249,360	)	$	73,603,967	$	75,158,087	$	187,001	$	(246,935	)	$	75,098,153
Municipal bonds		-		-		-			-		1,304,817		-		(214	)		1,304,603
Total	$	74,853,327	$	-	$	(1,249,360	)	$	73,603,967	$	76,462,904	$	187,001	$	(247,149	)	$	76,402,756

Schedule of Unrealized Loss on Investments [Table Text Block]

	Less Than 12 Months					12 Months or Greater					Total
	Fair Market Value		Gross Unrealized Losses			Fair Market Value		Gross Unrealized Losses			Fair Market Value		Gross Unrealized Losses
As of March 31, 2018 (corporate bonds)	$	61,731,248	$	(1,003,849	)	$	9,072,719	$	(245,511	)	$	70,803,967	$	(1,249,360	)
As of March 31, 2017
Corporate bonds	$	32,198,766	$	(246,935	)	$	-	$	-		$	32,198,766	$	(246,935	)
Municipal bonds		1,304,603		(214	)		-		-			1,304,603		(214	)
Total	$	33,503,369	$	(247,149	)	$	-	$	-		$	33,503,369	$	(247,149	)