Note 5 - Reconciliation of Marketable Securities (Details) - USD ($)	Sep. 30, 2016	Mar. 31, 2016
Corporate Bond Securities [Member]
Adjusted Cost	$ 81,087,271	$ 83,339,487
Gross Unrealized Gains	719,992	717,206
Gross Unrealized Losses	(34,699)	(10,824)
Total	81,772,564	84,045,869
Municipal Bonds [Member]
Adjusted Cost	1,324,572	1,344,328
Gross Unrealized Gains		2,522
Gross Unrealized Losses	(271)
Total	1,324,301	1,346,850
Adjusted Cost	82,411,843	84,683,815
Gross Unrealized Gains	719,992	719,728
Gross Unrealized Losses	(34,970)	(10,824)
Total	$ 83,096,865	$ 85,392,719