Note 4 - Equipment and Leasehold Improvements, Net - Components of Equipment and Leasehold Improvements (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Mar. 31, 2019
Equipment and leasehold improvements, gross	$ 33,908	$ 33,750
Less accumulated depreciation and amortization	(20,702)	(19,254)
Construction-in-progress	268	256
Equipment and leasehold improvements, net	13,474	14,752
Equipment [Member]
Equipment and leasehold improvements, gross	18,804	18,679
Leasehold Improvements [Member]
Equipment and leasehold improvements, gross	14,735	14,723
Furniture and Fixtures [Member]
Equipment and leasehold improvements, gross	$ 369	$ 348

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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