Note 5 - Marketable Securities - Gross Unrealized Losses and Fair Value of Investments (Details) - USD ($)
|
9 Months Ended |
12 Months Ended |
Dec. 31, 2016 |
Mar. 31, 2016 |
| Fair market value, less than 12 months |
$ 31,460,549
|
$ 3,003,606
|
| Gross unrealized losses, less than 12 months |
(336,187)
|
(6,703)
|
| Fair market value, greater than 12 months |
|
2,599,870
|
| Gross unrealized losses, greater than 12 months |
|
(4,121)
|
| Total Fair Market Value |
31,460,549
|
5,603,476
|
| Total Gross Unrealized Losses |
(336,187)
|
(10,824)
|
| Corporate Bond Securities [Member] |
|
|
| Fair market value, less than 12 months |
30,147,097
|
3,003,606
|
| Gross unrealized losses, less than 12 months |
(334,944)
|
(6,703)
|
| Fair market value, greater than 12 months |
|
2,599,870
|
| Gross unrealized losses, greater than 12 months |
|
(4,121)
|
| Total Fair Market Value |
30,147,097
|
5,603,476
|
| Total Gross Unrealized Losses |
(334,944)
|
(10,824)
|
| Municipal Bonds [Member] |
|
|
| Fair market value, less than 12 months |
1,313,452
|
|
| Gross unrealized losses, less than 12 months |
(1,243)
|
|
| Fair market value, greater than 12 months |
|
|
| Gross unrealized losses, greater than 12 months |
|
|
| Total Fair Market Value |
1,313,452
|
|
| Total Gross Unrealized Losses |
$ (1,243)
|
|