Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2017	Mar. 31, 2016
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	$ 9,228	$ 9,432
Intangible assets, Accumulated Amortization	(8,927)	(8,578)
Intangible assets, Net Book Value	301	854
Licenses
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	4,422	4,422
Intangible assets, Accumulated Amortization	(4,134)	(3,739)
Intangible assets, Net Book Value	$ 288	683
Intangible assets, Estimated Useful Life	7 years
Core Technology And Know How
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	$ 4,806	5,010
Intangible assets, Accumulated Amortization	(4,793)	(4,839)
Intangible assets, Net Book Value	$ 13	$ 171
Core Technology And Know How | Minimum
Finite Lived Intangible Assets [Line Items]
Intangible assets, Estimated Useful Life	5 years
Core Technology And Know How | Maximum
Finite Lived Intangible Assets [Line Items]
Intangible assets, Estimated Useful Life	10 years