Note 4 - Stock-based Compensation (Details Textual) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Sep. 30, 2026	Sep. 30, 2025	Sep. 30, 2026	Sep. 30, 2025
Restricted Stock [Member]
Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture (in shares)	10,500	7,000	815,900	887,000
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount	$ 48.2		$ 48.2
Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition (Year)			1 year 9 months 18 days
Restricted Stock [Member] \| Minimum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			2 years
Restricted Stock [Member] \| Maximum [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)			3 years
Immediately Vested Common Stock [Member]
Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture (in shares)	1,607	0	19,852	39,445
Share-Based Payment Arrangement, Option [Member]
Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period (Year)				2 years
Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross (in shares)	0	0	0	2,112
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

Amount of cost not yet recognized for nonvested award under share-based payment arrangement.

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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.

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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.

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Number, after forfeiture, of shares or units issued under share-based payment arrangement. Excludes shares or units issued under employee stock ownership plan (ESOP).

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