Financial Instruments - Carrying Amounts and Fair Values of Financial Instruments, Other than Cash and Cash Equivalents, Receivables and Accounts Payable (Detail) $ in Thousands	Apr. 30, 2018 USD ($)
Schedule Of Carrying Amounts And Fair Values Of Financial Instruments [Abstract]
Long-term debt, including current maturities, Carrying Amount	$ 1,539,046
Foreign currency forward contracts (net), Carrying Amount	(2,281)
Long-term debt, including current maturities, Fair Value	1,529,148
Foreign currency forward contracts (net), Fair Value	$ (2,281)