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Business Segments - Additional Information (Detail) $ in Thousands | 12 Months Ended
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Mar. 31, 2016 USD ($) Segment MW | Mar. 31, 2015 USD ($) | Mar. 31, 2014 USD ($)
Segment Reporting Information [Line Items] |  |  |
Number of reportable business segments | Segment | 2 |  |
Stock-based compensation expense | $ 3,248 | $ 5,936 | $ 10,696
Restructuring and impairment charges | $ 779 | $ 5,366 | $ 2,998
Geographic Concentration Risk | Sales Revenue, Net | Outside The United States |  |  |
Segment Reporting Information [Line Items] |  |  |
Risk percentage | 85.00% | 86.00% | 87.00%
Customer Concentration Risk | Sales Revenue, Net | Inox Wind Limited |  |  |
Segment Reporting Information [Line Items] |  |  |
Risk percentage | 62.00% | 56.00% | 31.00%
Customer Concentration Risk | Sales Revenue, Net | Beijing JINGCHENG |  |  |
Segment Reporting Information [Line Items] |  |  |
Risk percentage |  |  | 18.00%
Minimum |  |  |
Segment Reporting Information [Line Items] |  |  |
Megawatts of drive trains and power ratings | MW | 2 |  |

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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 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 14 -Section F + Details
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