Income Taxes (Detail) - USD ($)	3 Months Ended		6 Months Ended
	Oct. 26, 2019	Oct. 27, 2018	Oct. 26, 2019	Oct. 27, 2018
Income Tax Disclosure [Abstract]
Income tax expense	$ 6,426,000	$ 9,055,000	$ 16,520,000	$ 8,110,000
Loss before taxes	(26,923,000)	$ 37,701,000	$ 12,978,000	$ 32,247,000
Effective income tax rate		24.00%	127.30%	25.10%
Litigation settlement expenses	$ 58,300