Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) Share data in Thousands, unless otherwise specified	12 Months Ended
	Apr. 26, 2014 Segment	Apr. 27, 2013	Apr. 28, 2012
Summary Of Significant Accounting Policies [Line Items]
Number of reportable segments	3
Maturity period of maximum (in days)	90 days
Inventories valued at LIFO as % of total inventories	75.00%	83.00%
Accumulated LIFO reserve	$ 74,607,000	$ 70,415,000
Estimated fair value of reporting unit exceeding book value	6.00%
Asset impairment charges	0	0	0
Consolidated net sales, percentage	2.00%
Percentage of liability recorded	87.00%
Total advertising and promotional expenses	18,263,000	19,721,000	18,811,000
Deferred direct-marketing expenses included in prepaid and other current assets	$ 2,031,000	$ 1,845,000
Unvested restricted stock award	0	0	140
Stock Options [Member]
Summary Of Significant Accounting Policies [Line Items]
Securities excluded from calculation of diluted earnings per share	39	362	520
Building [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	39 years
Computer Equipment [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	3 years
Communications and Data Processing [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Office Furniture And Equipment [Member] | Minimum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	5 years
Office Furniture And Equipment [Member] | Maximum [Member]
Summary Of Significant Accounting Policies [Line Items]
Estimated useful lives	10 years