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Intangible Assets - Additional Information (Detail) - USD ($)
$ in Millions
3 Months Ended
Jul. 31, 2018
Jul. 31, 2017
Finite-Lived Intangible Assets [Line Items]    
Amortization expense of intangible assets $ 5.4 $ 5.7
Weighted-average period for amortization of intangible assets 5 years  
Customer relationships    
Finite-Lived Intangible Assets [Line Items]    
Weighted-average period for amortization of intangible assets 5 years  
Developed technology    
Finite-Lived Intangible Assets [Line Items]    
Weighted-average period for amortization of intangible assets 6 years  
Patents, trademarks, and trade names    
Finite-Lived Intangible Assets [Line Items]    
Weighted-average period for amortization of intangible assets 5 years