Business Segments - Total Business Segments Assets (Detail) - USD ($) $ in Thousands	Mar. 31, 2017	Mar. 31, 2016
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	$ 100,244	$ 135,318
Operating Segments | Wind
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	18,346	34,389
Operating Segments | Grid
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	31,060	36,255
Corporate assets
Segment Reporting Asset Reconciling Item [Line Items]
Total assets	$ 50,838	$ 64,674