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Revenue Recognition - Additional Information (Detail) - USD ($) $ in Thousands | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Sep. 30, 2019 | Sep. 30, 2018 | Sep. 30, 2019 | Sep. 30, 2018 | Mar. 31, 2019
Contract With Customer Assets And Liabilities [Line Items] |  |  |  |  |
Percentage of revenue from contracts recognized over time | 70.00% | 65.00% | 65.00% | 65.00% |
Percentage of revenue from contracts recognized upon shipment | 30.00% | 35.00% | 35.00% | 35.00% |
Revenue recognized included in contract liability | $ 5,610 |  | $ 11,032 |  |
Unbilled revenue (contract assets) |  |  | 5,514 |  |
Contract with customer liability increase in contract asset due to contract progress. |  |  | 6,590 |  |
Contract with customer liability offset by invoicing to customers. |  |  | 1,076 |  |
Customer deposits, current |  |  | 1,238 |  |
Contract with customer liability offset by new customer deposits. | 9,794 |  | 9,794 |  |
Receivables billed but not paid under retainage provisions in its customer contracts | 2,319 |  | 2,319 |  | $ 2,214
Amortization expense | 40 | $ 42 | 86 | $ 82 |
Revenue remaining unsatisfied performance obligations amount | 127,765 |  | 127,765 |  |
Customer Deposit [Member] |  |  |  |  |
Contract With Customer Assets And Liabilities [Line Items] |  |  |  |  |
Contract liabilities | 3,904 |  | 3,904 |  | 6,382
Prepaid Expenses and Other Current Assets [Member] |  |  |  |  |
Contract With Customer Assets And Liabilities [Line Items] |  |  |  |  |
Capitalized costs, net of amortization | $ 100 |  | $ 100 |  | $ 133

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