Employee Stock Ownership Plan (ESOP) - Additional Information (Detail) (USD $)	3 Months Ended		6 Months Ended
	Oct. 26, 2013	Oct. 27, 2012	Oct. 26, 2013	Oct. 27, 2012
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	3,018,992		3,018,992
ESOP compensation	$ 5,700	$ 5,700	$ 11,400	$ 11,400
2002 note
Shareholders Equity [Line Items]
ESOP company loan	12,612,000		12,612,000
2006 note
Shareholders Equity [Line Items]
ESOP company loan	$ 105,000,000		$ 105,000,000