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Business Segments - Schedule of Revenues by Major Customers (Detail) - Total Revenue - Customer Concentration Risk | 3 Months Ended | 6 Months Ended
--- | --- | ---
Sep. 30, 2016 | Sep. 30, 2015 | Sep. 30, 2016 | Sep. 30, 2015
INOX Wind Limited |  |  |  |
Segment Reporting Asset Reconciling Item [Line Items] |  |  |  |
Concentration risk, revenue (less than 10% 3 months ended 2015, nine months ended 2016) | 68.00% | 66.00% | 51.00% | 55.00%
Beijing JINGCHENG New Energy Co., Ltd |  |  |  |
Segment Reporting Asset Reconciling Item [Line Items] |  |  |  |
Concentration risk, revenue (less than 10% 3 months ended 2015, nine months ended 2016) | 0.00% | 10.00% | 10.00% | 15.00%

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