Employee Stock Ownership Plan (ESOP) - Additional Information (Detail) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Oct. 25, 2014	Oct. 26, 2013	Oct. 25, 2014	Oct. 26, 2013
Shareholders Equity [Line Items]
Hours of service completed in order to be allocated shares of stock acquired by plan			1000 hours
Number of unallocated shares held by ESOP	2,736,969		2,736,969
ESOP compensation	$ 3,000	$ 5,700	$ 6,000	$ 11,400
2002 note [Member]
Shareholders Equity [Line Items]
ESOP company loan	12,612		12,612
2006 note [Member]
Shareholders Equity [Line Items]
ESOP company loan	$ 105,000		$ 105,000