Annual report pursuant to Section 13 and 15(d)

Financial Instruments - Additional Information (Detail)

v3.7.0.1
Financial Instruments - Additional Information (Detail) - USD ($)
$ in Millions
1 Months Ended 12 Months Ended
Mar. 31, 2017
Apr. 30, 2017
Apr. 30, 2016
Apr. 30, 2015
Financial Instrument [Line Items]        
Proceeds from maturities of available-for-sale securities     $ 13.1 $ 5.0
Derivative losses included in AOCI   $ (0.8)    
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts        
Financial Instrument [Line Items]        
Foreign currency gains (losses)   0.6 (1.8)  
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Other Accrued Liabilities | Derivatives Purchased        
Financial Instrument [Line Items]        
Derivative notional amount   19.4 14.5  
Not Designated as Hedge Instrument | Foreign Exchange Forward Contracts | Other Accrued Liabilities | Derivatives Sold        
Financial Instrument [Line Items]        
Derivative notional amount   $ 70.0 $ 44.3  
Designated as Hedge Instrument | Interest Rate Swap | Cash Flow Hedge        
Financial Instrument [Line Items]        
Derivative notional amount $ 129.8      
Derivative, Maturity Date Jun. 15, 2021      
Interest rate 1.919%