Intangible Assets - Summary of Intangible Assets (Detail) - USD ($) $ in Thousands	Jul. 31, 2016	Apr. 30, 2016
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	$ 81,198	$ 81,066
Finite lived intangible assets, Accumulated Amortization	(21,286)	(18,575)
Finite lived intangible assets, Net Carrying Amount	59,912	62,491
Intangible assets, Gross Carrying Amount	81,632	81,499
Intangible assets, Net Carrying Amount	60,346	62,924
Patents in progress
Finite-Lived Intangible Assets [Line Items]
Deposits on patents	434	433
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	28,560	28,560
Finite lived intangible assets, Accumulated Amortization	(7,504)	(6,423)
Finite lived intangible assets, Net Carrying Amount	21,056	22,137
Developed technology
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	16,430	16,430
Finite lived intangible assets, Accumulated Amortization	(3,394)	(2,890)
Finite lived intangible assets, Net Carrying Amount	13,036	13,540
Patents, trademarks, and trade names
Finite-Lived Intangible Assets [Line Items]
Finite lived intangible assets, Gross Carrying Amount	36,208	36,076
Finite lived intangible assets, Accumulated Amortization	(10,388)	(9,262)
Finite lived intangible assets, Net Carrying Amount	$ 25,820	$ 26,814