Note 5 - Reconciliation of Marketable Securities (Details) - USD ($) |
Sep. 30, 2015 |
Mar. 31, 2015 |
|---|---|---|
| Corporate Bond Securities [Member] | ||
| Adjusted Cost | $ 81,960,402 | $ 88,456,886 |
| Gross Unrealized Gains | 645,841 | 1,185,469 |
| Gross Unrealized Losses | (17,615) | (16,371) |
| Available-for-sale Securities, Debt Securities | 82,588,628 | 89,625,984 |
| Municipal Bonds [Member] | ||
| Adjusted Cost | 1,364,084 | 1,383,839 |
| Gross Unrealized Gains | $ 4,064 | $ 3,272 |
| Gross Unrealized Losses | ||
| Available-for-sale Securities, Debt Securities | $ 1,368,148 | $ 1,387,111 |
| Adjusted Cost | 83,324,486 | 89,840,725 |
| Gross Unrealized Gains | 649,905 | 1,188,741 |
| Gross Unrealized Losses | (17,615) | (16,371) |
| Available-for-sale Securities, Debt Securities | $ 83,956,776 | $ 91,013,095 |