Derivative Financial Instruments - Effect of Derivative Instruments in Cash Flow Hedging Relationships on Condensed Consolidated Statements of Income and Other Comprehensive Income (OCI) (Detail) - USD ($) $ in Thousands	3 Months Ended
	Jul. 28, 2018	Jul. 29, 2017
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive loss expected to be reclassified into earnings	$ (2,900)
Interest Rate Swap
Derivative Instruments, Gain (Loss) [Line Items]
Accumulated other comprehensive loss expected to be reclassified into earnings	$ (733)	$ (702)