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Note 3 - Stock-based Compensation (Details Textual) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Sep. 30, 2023 | Sep. 30, 2022 | Sep. 30, 2023 | Sep. 30, 2022
Restricted Stock [Member] |  |  |  |
Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture (in shares) | 9,000 | 338,500 | 681,500 | 338,500
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 6.8 |  | $ 6.8 |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  |  | 2 years |
Restricted Stock [Member] | Minimum [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) |  |  | 2 years |
Immediately Vested Common Stock [Member] |  |  |  |
Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture (in shares) | 0 | 0 | 53,675 | 25,806
Share-Based Payment Arrangement, Option [Member] |  |  |  |
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period (Year) |  |  |  | 2 years
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount | $ 0.1 |  | $ 0.1 |
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year) |  |  | 8 months 12 days |
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares) | 0 | 0 | 0 | 20,564

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- Definition Amount of cost not yet recognized for nonvested award under share-based payment arrangement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition Weighted-average period over which cost not yet recognized is expected to be recognized for award under share-based payment arrangement, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (i) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition Period over which grantee's right to exercise award under share-based payment arrangement is no longer contingent on satisfaction of service or performance condition, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days. Includes, but is not limited to, combination of market, performance or service condition. + References Reference 1: http://www.xbrl.org/2003/role/exampleRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (a)(1) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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- Definition Gross number of share options (or share units) granted during the period. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Topic 718 -SubTopic 10 -Name Accounting Standards Codification -Section 50 -Paragraph 2 -Subparagraph (c)(1)(iv)(01) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480429/718-10-50-2 + Details
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