Segment Reporting (Sales Information By Product) (Details) (USD $) In Thousands	3 Months Ended
Jul. 30, 2011	Jul. 31, 2010
Net sales	$ 847,422	$ 849,787
Consumable And Printed Products [Member]
Net sales	574,962	586,603
Equipment And Software [Member]
Net sales	199,651	192,221
Other [Member]
Net sales	$ 72,809	$ 70,963

Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 5
-Section 03
-Paragraph 1

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.1)
-URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688

Name:	us-gaap_SalesRevenueNet
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration