Note 4 - Equipment and Leasehold Improvements, Net - Components of Equipment and Leasehold Improvements (Details) - USD ($) $ in Thousands	Sep. 30, 2018	Mar. 31, 2018
Equipment and leasehold improvements, gross	$ 32,812	$ 32,531
Less accumulated depreciation and amortization	(18,296)	(17,346)
Construction-in-progress	606	549
Equipment and leasehold improvements, net	15,122	15,734
Equipment [Member]
Equipment and leasehold improvements, gross	18,176	17,935
Leasehold Improvements [Member]
Equipment and leasehold improvements, gross	14,288	14,248
Furniture and Fixtures [Member]
Equipment and leasehold improvements, gross	$ 348	$ 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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