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Business Segments - Operating Results for Two Business Segments (Detail) - USD ($) $ in Thousands | 3 Months Ended | 9 Months Ended
--- | --- | ---
Dec. 31, 2018 | Dec. 31, 2017 | Dec. 31, 2018 | Dec. 31, 2017
Segment Reporting Information [Line Items] |  |  |  |
Revenues | $ 14,134 | $ 14,933 | $ 41,618 | $ 34,904
Operating profit/(loss) | 20,765 | (3,851) | 40,366 | (26,350)
Unallocated corporate expenses |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating profit/(loss) | (839) | (1,156) | (2,851) | (3,514)
Wind |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 7,308 | 2,633 | 18,293 | 10,465
Wind | Operating Segments |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating profit/(loss) | 24,269 | (1,684) | 51,419 | (7,557)
Grid |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Revenues | 6,826 | 12,300 | 23,325 | 24,439
Grid | Operating Segments |  |  |  |
Segment Reporting Information [Line Items] |  |  |  |
Operating profit/(loss) | $ (2,665) | $ (1,011) | $ (8,202) | $ (15,279)

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