| Inventories - Major Classifications of Inventories (Detail) - USD ($) $ in Thousands | Mar. 31, 2021 | Mar. 31, 2020 | 
|---|---|---|
| Inventory Disclosure [Abstract] | ||
| Raw materials and supplies | $ 3,490 | $ 3,061 | 
| Work in process | 12,196 | 18,018 | 
| Finished products | 1,646 | 1,212 | 
| Total | $ 17,332 | $ 22,291 | 
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- References No definition available. 
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| X | ||||||||||
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- Definition Amount before valuation and LIFO reserves of completed merchandise or goods expected to be sold within one year or operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
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- Definition Amount after valuation and LIFO reserves of inventory expected to be sold, or consumed within one year or operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
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- Definition Amount before valuation and LIFO reserves of raw materials expected to be sold, or consumed within one year or operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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| X | ||||||||||
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- Definition Amount before valuation and LIFO reserves of merchandise or goods in the production process expected to be completed within one year or operating cycle, if longer. Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef 
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