Note 4 - Equipment and Leasehold Improvements, Net - Components of Equipment and Leasehold Improvements (Details) - USD ($) $ in Thousands	Mar. 31, 2025	Mar. 31, 2024
Equipment and leasehold improvements, gross	$ 37,529	$ 37,398
Less accumulated depreciation and amortization	(28,885)	(27,500)
Construction in-progress	283	211
Equipment and leasehold improvements, net	8,927	10,109
Equipment [Member]
Equipment and leasehold improvements, gross	21,972	21,904
Leasehold Improvements [Member]
Equipment and leasehold improvements, gross	15,138	15,075
Furniture and Fixtures [Member]
Equipment and leasehold improvements, gross	$ 419	$ 419

Amount of accumulated depreciation, depletion and amortization for physical assets used in the normal conduct of business to produce goods and services.

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Amount of structure or a modification to a structure under construction. Includes recently completed structures or modifications to structures that have not been placed into service.

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