Fair Value of Interest Rate Contracts (Detail) (USD $) In Thousands, unless otherwise specified	Jan. 26, 2013	Apr. 28, 2012	Jan. 28, 2012
Derivatives, Fair Value [Line Items]
Interest rate contracts, assets	$ 138	$ 245
Interest rate contracts, liabilities	165	245
Other noncurrent assets
Derivatives, Fair Value [Line Items]
Interest rate contracts, assets	138	245	338
Other noncurrent liabilities
Derivatives, Fair Value [Line Items]
Interest rate contracts, liabilities	$ 165	$ 245	$ 338

Fair value as of the balance sheet date of interest rate derivative liabilities, which includes all such derivative instruments in hedging and nonhedging relationships that are recognized as liabilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=7491637&loc=d3e13433-108611

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 107

-Paragraph 10

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant