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Assets Dispositions - Additional Information (Detail) - USD ($) $ in Thousands |  | 3 Months Ended | 12 Months Ended
--- | --- | --- | ---
Jun. 24, 2019 | Mar. 31, 2019 | Mar. 31, 2020 | Mar. 31, 2019 | Mar. 31, 2018
Income Statement Balance Sheet And Additional Disclosures By Disposal Groups Including Discontinued Operations [Line Items] |  |  |  |  |
Impairment loss |  | $ 6,449 |  | $ 6,449 | $ 14,816
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 |  |  |  |
Working capital adjustment determination period | 90 days |  |  |  |
Net accounts receivable | $ 202 |  |  |  |
Loss on sale of Energy Steel & Supply Co. |  |  | $ 181 |  |

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