Note 9 - Fair Value Measurements (Details Textual) - USD ($) |
Sep. 30, 2015 |
Mar. 31, 2015 |
|---|---|---|
| Fair Value, Inputs, Level 1 [Member] | Corporate Bond Securities [Member] | ||
| Available-for-sale Securities, Debt Securities | $ 82,588,628 | $ 89,625,984 |
| Fair Value, Inputs, Level 2 [Member] | Municipal Bonds [Member] | ||
| Available-for-sale Securities, Debt Securities | 1,368,148 | 1,387,111 |
| Corporate Bond Securities [Member] | ||
| Available-for-sale Securities, Debt Securities | 82,588,628 | 89,625,984 |
| Municipal Bonds [Member] | ||
| Available-for-sale Securities, Debt Securities | 1,368,148 | 1,387,111 |
| Available-for-sale Securities, Debt Securities | $ 83,956,776 | $ 91,013,095 |