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Assets Dispositions - Additional Information (Detail) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Mar. 31, 2021 | Mar. 31, 2020 | Mar. 31, 2019
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |
Impairment loss | $ 184 |  | $ 6,449
Proceeds from sale of subsidiary |  | $ 602 |
Loss on sale of Energy Steel & Supply Co. |  | 181 |
Westinghouse Electric Company [Member] |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |
Bad debt charge |  | 98 |
Inventory write down |  | 338 |
Energy Steel [Member] |  |  |
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |
Proceeds from sale of subsidiary |  | 602 |
Loss on sale of Energy Steel & Supply Co. |  | $ 181 |

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