Commitments and Contingencies (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Apr. 25, 2015	Jul. 26, 2014
Loss Contingencies [Line Items]
Loss Contingency, Damages Sought	2.6
Performance Guarantee and Surety Bond
Loss Contingencies [Line Items]
Outstanding performance and other surety contract bonds	308.7	$ 446.8

Describes the form and magnitude of the award the plaintiff seeks in the legal matter, which may include an unspecified amount of money.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 4

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14435-108349

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 450

-SubTopic 20

-Section 50

-Paragraph 9

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14557-108349

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Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration