Business Segments - Total Business Segments Assets (Detail) - USD ($) $ in Thousands	Jun. 30, 2016	Mar. 31, 2016
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	$ 126,051	$ 135,318
Operating Segments | Wind
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	25,704	34,389
Operating Segments | Grid
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	40,027	36,255
Corporate assets
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	$ 60,320	$ 64,674