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The Company and Its Accounting Policies - Additional Information (Detail) - USD ($) shares in Thousands, $ in Thousands |  | 12 Months Ended
--- | --- | ---
Apr. 01, 2018 | Mar. 31, 2018 | Mar. 31, 2017 | Mar. 31, 2016
Schedule Of Accounting Policies [Line Items] |  |  |  |
Company recognizes planned manufacturing process |  | 28 days |  |
Direct labor hours worked on contracts |  | 575 hours |  |
Receivables billed but not paid under retainage provisions in its customer contracts |  | $ 1,124 | $ 971 |
Substantial completion of manufacturing process |  | 95.00% |  |
Minimum level of likelihood |  | 50.00% |  |
Research and development costs |  | $ 3,211 | $ 3,863 | $ 3,746
Antidilutive securities excluded from computation of earnings per share |  | 69 | 11 | 54
Interest paid |  | $ 12 | $ 10 | $ 10
Income taxes paid |  | 1,916 | 951 | 5,423
Pension and other postretirement benefit adjustments, net of tax |  | (1,668) | (2,493) | 1,470
Reclassification from accumulated other comprehensive loss to retaIned earnings |  | 1,828 |  |
Issuance of treasury stock |  | 130 | 241 | 255
Capital expenditures |  | 0 | 4 | 53
Capital leases |  | 0 | $ 95 | $ 126
ASU 2018-02 [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Reclassification from accumulated other comprehensive loss to retaIned earnings |  | $ 1,828 |  |
Subsequent Event [Member] | ASU 2014-09 [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Change in accounting principle cumulative-effect of amended as a decrease to opening balance of retained earnings | $ 1,000 |  |  |
Delay in recognizing net sales | $ 5,000 |  |  |
Customer Relationships [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Estimated useful lives |  | 15 years |  |
Buildings and Leasehold Improvements [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Estimated useful lives range |  | 40 years |  |
Minimum [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Treasury with original maturities period |  | 3 months |  |
Minimum [Member] | Office Equipment [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Estimated useful lives range |  | 5 years |  |
Minimum [Member] | Manufacturing Equipment [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Estimated useful lives range |  | 8 years |  |
Maximum [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Treasury with original maturities period |  | 1 year |  |
Investment maturity date range end |  | Jul. 18, 2018 |  |
Maximum [Member] | Office Equipment [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Estimated useful lives range |  | 8 years |  |
Maximum [Member] | Manufacturing Equipment [Member] |  |  |  |
Schedule Of Accounting Policies [Line Items] |  |  |  |
Estimated useful lives range |  | 25 years |  |

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