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Changes in Accumulated Other Comprehensive Loss - Reclassifications Out of Accumulated Other Comprehensive Loss by Component (Detail) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Income before provision for income taxes | $ 3,517 | $ 1,547 | $ 1,327 | $ 1,654
Provision for income taxes | 773 | 342 | 401 | 367
Net income | 2,744 | 1,205 | 926 | 1,287
Reclassifications Out of Accumulated Other Comprehensive Loss [Member] | Amortization of Actuarial Loss [Member] |  |  |  |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Income before provision for income taxes | (267) | (249) | (533) | (498)
Reclassifications Out of Accumulated Other Comprehensive Loss [Member] | Pension and Other Postretirement Benefits Items [Member] |  |  |  |
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |
Provision for income taxes | (63) | (54) | (124) | (109)
Net income | $ (204) | $ (195) | $ (409) | $ (389)

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