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Business Segments - Operating Results for Two Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2017	Dec. 31, 2016
Segment Reporting Information [Line Items]
Revenues	$ 14,933	$ 27,148	$ 34,904	$ 59,000
Operating loss	(3,851)	(4,060)	(26,350)	(20,554)
Unallocated corporate expenses
Segment Reporting Information [Line Items]
Operating loss	(1,156)	(613)	(3,514)	(2,266)
Wind
Segment Reporting Information [Line Items]
Revenues	2,633	18,248	10,465	36,822
Wind | Operating Segments
Segment Reporting Information [Line Items]
Operating loss	(1,684)	1,044	(7,557)	(3,220)
Grid
Segment Reporting Information [Line Items]
Revenues	12,300	8,900	24,439	22,178
Grid | Operating Segments
Segment Reporting Information [Line Items]
Operating loss	$ (1,011)	$ (4,491)	$ (15,279)	$ (15,068)

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- Definition

The net result for the period of deducting operating expenses from operating revenues.

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- Definition

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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