Note 5 - Fair Value of Financial Instruments (Tables)
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3 Months Ended |
Jun. 30, 2021 |
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| Notes Tables |
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| Investments Classified by Contractual Maturity Date [Table Text Block] |
| Total | | | <1 Year | | | 1–3 Years | | | 3–5 Years | |
| $ | 62,756,448 | | | $ | 25,293,411 | | | $ | 27,108,299 | | | $ | 10,354,738 | |
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| Fair Value, Assets Measured on Recurring Basis [Table Text Block] |
| | | As of June 30, 2021 | | | As of March 31, 2021 | |
| | | Level 1 | | | Level 2 | | | Total | | | Level 1 | | | Level 2 | | | Total | |
| Money market funds | | $ | 8,231,700 | | | $ | - | | | $ | 8,231,700 | | | $ | 10,143,196 | | | $ | - | | | $ | 10,143,196 | |
| Corporate bonds | | | - | | | | 54,524,748 | | | | 54,524,748 | | | | - | | | | 54,717,626 | | | | 54,717,626 | |
| Total | | $ | 8,231,700 | | | $ | 54,524,748 | | | $ | 62,756,448 | | | $ | 10,143,196 | | | $ | 54,717,626 | | | $ | 64,860,822 | |
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| Schedule of Available-for-sale Securities Reconciliation [Table Text Block] |
| | | As of June 30, 2021 | | | As of March 31, 2021 | |
| | | Amortized
Cost | | | Gross
Unrealized
Holding Gains | | | Gross
Unrealized
Holding Losses | | | Estimated
Fair
Value | | | Amortized
Cost | | | Gross
Unrealized
Holding Gains | | | Gross
Unrealized
Holding Losses | | | Estimated
Fair
Value | |
| Money market funds | | $ | 8,231,700 | | | $ | - | | | $ | - | | | $ | 8,231,700 | | | $ | 10,143,196 | | | $ | - | | | $ | - | | | $ | 10,143,196 | |
| Corporate bonds | | | 53,230,646 | | | | 1,389,752 | | | | (95,650 | ) | | | 54,524,748 | | | | 53,308,105 | | | | 1,570,195 | | | | (160,674 | ) | | | 54,717,626 | |
| Total | | $ | 61,462,346 | | | $ | 1,389,752 | | | $ | (95,650 | ) | | $ | 62,756,448 | | | $ | 63,451,301 | | | $ | 1,570,195 | | | $ | (160,674 | ) | | $ | 64,860,822 | |
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| Debt Securities, Available-for-sale, Unrealized Loss Position, Fair Value [Table Text Block] |
| | | Less Than 12 Months | | | 12 Months or Greater | | | Total | |
| | | Estimated
Fair
Value | | | Gross
Unrealized
Holding Losses | | | Estimated
Fair
Value | | | Gross
Unrealized
Holding Losses | | | Estimated
Fair
Value | | | Gross
Unrealized
Holding Losses | |
| | | | | | | | | | | | | | | | | | | | | | | | | |
| As of June 30, 2021 | | | | | | | | | | | | | | | | | | | | | | | | |
| Corporate bonds | | $ | 10,354,738 | | | $ | (95,650 | ) | | $ | - | | | $ | - | | | $ | 10,354,738 | | | $ | (95,650 | ) |
| Total | | $ | 10,354,738 | | | $ | (95,650 | ) | | $ | - | | | $ | - | | | $ | 10,354,738 | | | $ | (95,650 | ) |
| | | | | | | | | | | | | | | | | | | | | | | | | |
| As of March 31, 2021 | | | | | | | | | | | | | | | | | | | | | | | | |
| Corporate bonds | | $ | 10,322,539 | | | $ | (160,674 | ) | | $ | - | | | $ | - | | | $ | 10,322,539 | | | $ | (160,674 | ) |
| Total | | $ | 10,322,539 | | | $ | (160,674 | ) | | $ | - | | | $ | - | | | $ | 10,322,539 | | | $ | (160,674 | ) |
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