Business Segments - Geographic Information about Revenue, Based on Shipments to Customers by Region (Detail) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2017	Mar. 31, 2016	Mar. 31, 2015
Segment Reporting Information [Line Items]
Revenues	$ 16,195	$ 27,148	$ 18,507	$ 13,345	$ 27,524	$ 25,772	$ 19,004	$ 23,723	$ 75,195	$ 96,023	$ 70,530
India
Segment Reporting Information [Line Items]
Revenues									44,243	59,640	39,314
U.S.
Segment Reporting Information [Line Items]
Revenues									16,224	14,565	9,820
China
Segment Reporting Information [Line Items]
Revenues									2,004	8,455	10,410
Asia Pacific
Segment Reporting Information [Line Items]
Revenues									2,106	5,364	3,788
Africa
Segment Reporting Information [Line Items]
Revenues									1,548	2,697	616
Australia
Segment Reporting Information [Line Items]
Revenues									4,053	2,410	1,653
Europe
Segment Reporting Information [Line Items]
Revenues									3,624	1,775	2,239
Canada
Segment Reporting Information [Line Items]
Revenues									$ 1,393	$ 1,117	$ 2,690