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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
--- | ---
Jun. 30, 2018 | Jun. 30, 2017
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] |  |
Income before provision for income taxes | $ 3,025 | $ 1,333
Provision for income taxes | 702 | 398
Net income | 2,323 | 935
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 | (219) | (263)
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 | (49) | (93)
Net income | $ (170) | $ (170)

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