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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 | 12 Months Ended
--- | --- | ---
Mar. 31, 2018 | Dec. 31, 2017 | Sep. 30, 2017 | Jun. 30, 2017 | Mar. 31, 2017 | Dec. 31, 2016 | Sep. 30, 2016 | Jun. 30, 2016 | Mar. 31, 2018 | Mar. 31, 2017 | Mar. 31, 2016
Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] |  |  |  |  |  |  |  |  |  |  |
Income before provision for income taxes |  |  |  |  |  |  |  |  | $ (12,854) | $ 7,049 | $ 8,730
Provision for income taxes |  |  |  |  |  |  |  |  | (3,010) | 2,026 | 2,599
Net income | $ 833 | $ (11,622) | $ 10 | $ 935 | $ 1,801 | $ 1,840 | $ 1,297 | $ 85 | (9,844) | 5,023 | $ 6,131
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 |  |  |  |  |  |  |  |  | (1,050) | (1,387) |
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] |  |  |  |  |  |  |  |  |  |  |
Income before provision for income taxes |  |  |  |  |  |  |  |  | (1,050) | (1,387) |
Provision for income taxes |  |  |  |  |  |  |  |  | (233) | (490) |
Net income |  |  |  |  |  |  |  |  | $ (817) | $ (897) |

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