Intangible Assets - Schedule of Intangible Assets (Detail) - USD ($) $ in Thousands	12 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	$ 13,025	$ 9,228
Intangible assets, Accumulated Amortization	(9,795)	(8,927)
Total	3,230	301
Licenses
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	4,322	4,422
Intangible assets, Accumulated Amortization	(4,322)	(4,134)
Total	$ 0	288
Intangible assets, Estimated Useful Life	7 years
Core Technology And Know How
Finite Lived Intangible Assets [Line Items]
Intangible assets, Gross Amount	$ 8,703	4,806
Intangible assets, Accumulated Amortization	(5,473)	(4,793)
Total	$ 3,230	$ 13
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