Annual report pursuant to Section 13 and 15(d)

Financial Instruments - Additional Information (Detail)

v3.20.2
Financial Instruments - Additional Information (Detail) - USD ($)
$ in Millions
12 Months Ended
Dec. 16, 2019
Apr. 30, 2020
Apr. 30, 2019
Apr. 30, 2018
Mar. 31, 2017
Financial Instrument [Line Items]          
Sale/maturities of available-for-sale marketable securities   $ 4.8      
Designated as Hedge Instrument | Interest Rate Swap | Cash Flow Hedge          
Financial Instrument [Line Items]          
Derivative notional amount         $ 129.8
Interest rate   1.919%      
Interest expense recognized on termination of interest rate swap $ 0.5        
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts          
Financial Instrument [Line Items]          
Foreign currency gains (losses)   $ (0.3) $ 1.2 $ (3.7)  
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Income Taxes And Other Receivables | Derivatives Purchased          
Financial Instrument [Line Items]          
Derivative notional amount   91.2 51.4    
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Income Taxes And Other Receivables | Derivatives Sold          
Financial Instrument [Line Items]          
Derivative notional amount   $ 41.8 40.0    
Available-for-sale Marketable Securities | Minimum          
Financial Instrument [Line Items]          
Marketable securities remaining maturity   1 month      
Available-for-sale Marketable Securities | Maximum          
Financial Instrument [Line Items]          
Marketable securities remaining maturity   12 months      
Mutual Funds          
Financial Instrument [Line Items]          
Unrealized loss relates to equity securities   $ 8.2 $ 4.7    
Unrealized gains relates to equity securities       $ 3.9