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Significant Accounting Policies - Summary of Estimated Useful Lives (Detail)
12 Months Ended
Apr. 30, 2017
Minimum | Building and improvements  
Property Plant And Equipment [Line Items]  
Estimated useful life 10 years
Minimum | Software and hardware  
Property Plant And Equipment [Line Items]  
Estimated useful life 2 years
Minimum | Machinery and equipment  
Property Plant And Equipment [Line Items]  
Estimated useful life 2 years
Maximum | Building and improvements  
Property Plant And Equipment [Line Items]  
Estimated useful life 40 years
Maximum | Software and hardware  
Property Plant And Equipment [Line Items]  
Estimated useful life 7 years
Maximum | Machinery and equipment  
Property Plant And Equipment [Line Items]  
Estimated useful life 10 years