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Business Segments - Additional Information (Detail) $ in Thousands | 3 Months Ended | 6 Months Ended
--- | --- | ---
Sep. 30, 2016 USD ($) | Sep. 30, 2015 USD ($) | Sep. 30, 2016 USD ($) segment MW | Sep. 30, 2015 USD ($)
Segment Reporting Information [Line Items] |  |  |  |
Number of reportable business segments | segment |  |  | 2 |
Stock-based compensation expense | $ 653 | $ 706 | $ 1,653 | $ 1,834
Impairment of minority interest investment |  |  | $ 0 | 746
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 | $ 700 | 700 | $ 1,700 | $ 1,800
Impairment of minority interest investment |  | $ 700 |  |

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- Definition Represents the expense recognized during the period arising from equity-based compensation arrangements (for example, shares of stock, unit, stock options or other equity instruments) with employees, directors and certain consultants qualifying for treatment as employees. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 14.F) -URI http://asc.fasb.org/extlink&oid=27013229&loc=d3e301413-122809 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5047-113901 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 718 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (h)(1)(i) -URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901 + Details
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