Note 5 - Reconciliation of Marketable Securities (Details) - USD ($)	Dec. 31, 2015	Mar. 31, 2015
Corporate Bond Securities [Member]
Adjusted Cost	$ 90,274,572	$ 88,456,886
Gross Unrealized Gains	280,496	1,185,469
Gross Unrealized Losses	(153,811)	(16,371)
Available-for-sale Securities, Debt Securities	90,401,257	89,625,984
Municipal Bonds [Member]
Adjusted Cost	1,354,206	1,383,839
Gross Unrealized Gains	$ 1,094	$ 3,272
Gross Unrealized Losses
Available-for-sale Securities, Debt Securities	$ 1,355,300	$ 1,387,111
Adjusted Cost	91,628,778	89,840,725
Gross Unrealized Gains	281,590	1,188,741
Gross Unrealized Losses	(153,811)	(16,371)
Available-for-sale Securities, Debt Securities	$ 91,756,557	$ 91,013,095