Note 5 - Reconciliation of Marketable Securities (Details) - USD ($)	Jun. 30, 2016	Mar. 31, 2016
Corporate Bond Securities [Member]
Adjusted Cost	$ 88,332,907	$ 83,339,487
Gross Unrealized Gains	1,060,409	717,206
Gross Unrealized Losses		(10,824)
Fair Market Value	89,393,316	84,045,869
Municipal Bonds [Member]
Adjusted Cost	1,334,451	1,344,328
Gross Unrealized Gains	2,827	2,522
Gross Unrealized Losses
Fair Market Value	1,337,278	1,346,850
Adjusted Cost	89,667,358	84,683,815
Gross Unrealized Gains	1,063,236	719,728
Gross Unrealized Losses		(10,824)
Fair Market Value	$ 90,730,594	$ 85,392,719

Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale.

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Amount of debt securities categorized neither as held-to-maturity nor trading.

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