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Schedule II - Valuation and Qualifying Accounts (Detail) - USD ($) $ in Thousands | 12 Months Ended
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Mar. 31, 2019 | Mar. 31, 2018 | Mar. 31, 2017
Reserve for Doubtful Accounts Receivable [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Period | $ 339 | $ 168 | $ 91
Charged to Costs and Expenses | (167) | 177 | 91
Charged to Other Accounts | (13) |  |
Deductions | (126) | (6) | (14)
Balance at End of Period | 33 | 339 | 168
Product Warranty Liability [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Period | 493 | 538 | 686
Charged to Costs and Expenses | 234 | 527 | 106
Charged to Other Accounts | (85) |  |
Deductions | (276) | (572) | (254)
Balance at End of Period | 366 | 493 | 538
Restructuring Reserve [Member] |  |  |
Valuation and Qualifying Accounts Disclosure [Line Items] |  |  |
Balance at Beginning of Period | 18 | 120 | 74
Charged to Costs and Expenses |  | 316 | 630
Deductions | $ (18) | (418) | (584)
Balance at End of Period |  | $ 18 | $ 120

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- Definition Amount of valuation and qualifying accounts and reserves. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-09) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e24092-122690 + Details
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