Note 4 - Reconciliation of Marketable Securities (Details) - USD ($)	Mar. 31, 2016	Mar. 31, 2015
Corporate Bond Securities [Member]
Adjusted Cost	$ 83,339,487	$ 88,456,886
Gross Unrealized Gains	717,206	1,185,469
Gross Unrealized Losses	(10,824)	(16,371)
Fair Market Value	84,045,869	89,625,984
Municipal Bonds [Member]
Adjusted Cost	1,344,328	1,383,839
Gross Unrealized Gains	$ 2,522	$ 3,272
Gross Unrealized Losses
Fair Market Value	$ 1,346,850	$ 1,387,111
Adjusted Cost	84,683,815	89,840,725
Gross Unrealized Gains	719,728	1,188,741
Gross Unrealized Losses	(10,824)	(16,371)
Fair Market Value	$ 85,392,719	$ 91,013,095