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 |