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Business Segments - Additional Information (Detail) $ in Thousands | 3 Months Ended
--- | ---
Jun. 30, 2017 USD ($) segment MW | Jun. 30, 2016 USD ($)
Segment Reporting Information [Line Items] |  |
Number of reportable business segments | segment | 2 |
Stock-based compensation expense | $ 754 | $ 999
Restructuring charges | $ 1,339 | 0
Minimum |  |
Segment Reporting Information [Line Items] |  |
Megawatts of drive trains and power ratings | MW | 2 |
Unallocated corporate expenses |  |
Segment Reporting Information [Line Items] |  |
Stock-based compensation expense | $ 800 | $ 1,000
Restructuring charges | $ 1,300 |

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