Business Segments - Operating Results for Two Business Segments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2015	Dec. 31, 2014
Segment Reporting Information [Line Items]
Revenues	$ 25,772	$ 21,250	$ 68,499	$ 45,401
Operating (loss) profit	(3,312)	(7,735)	(18,411)	(46,801)
Unallocated corporate expenses
Segment Reporting Information [Line Items]
Operating (loss) profit	(707)	(1,986)	(3,321)	(9,995)
Wind
Segment Reporting Information [Line Items]
Revenues	17,229	15,131	48,976	30,244
Wind | Operating Segments
Segment Reporting Information [Line Items]
Operating (loss) profit	(263)	1,301	(2,127)	(16,790)
Grid
Segment Reporting Information [Line Items]
Revenues	8,543	6,119	19,523	15,157
Grid | Operating Segments
Segment Reporting Information [Line Items]
Operating (loss) profit	$ (2,342)	$ (7,050)	$ (12,963)	$ (20,016)