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 |