Investments And Restricted Investments (Narrative) (Details) (USD $) In Millions, unless otherwise specified	Apr. 28, 2012	Apr. 30, 2011
Investment [Line Items]
Underlying assets in non-qualified deferred compensation program	$ 75.3	$ 72.7
Quoted Prices In Active Markets For Identical Assets (Level 1) [Member]
Investment [Line Items]
Underlying assets in non-qualified deferred compensation program	63.8	62.9
Significant Other Observable Inputs (Level 2) [Member]
Investment [Line Items]
Underlying assets in non-qualified deferred compensation program	$ 11.5	$ 9.8

Carrying amount as of the balance sheet date of assets held under deferred compensation agreements.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.17)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 17

-Article 5

Name:	us-gaap_DeferredCompensationPlanAssets
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant