Business Segments - Additional Information (Detail) $ in Thousands	12 Months Ended
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

Business segments power of wind turbines.

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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
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Reference 4: http://www.xbrl.org/2003/role/presentationRef
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For an entity that discloses a concentration risk in relation to quantitative amount, which serves as the "benchmark" (or denominator) in the equation, this concept represents the concentration percentage derived from the division.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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Number of segments reported by the entity. A reportable segment is a component of an entity for which there is an accounting requirement to report separate financial information on that component in the entity's financial statements.

+ References

No definition available.

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The aggregate amount provided for estimated restructuring charges, remediation costs, and asset impairment loss during an accounting period. Generally, these items are either unusual or infrequent, but not both (in which case they would be extraordinary items).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
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-Name Accounting Standards Codification
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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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No definition available.

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