Balance Sheet Details - Computer Software Net Book Value (Detail) (USD $) In Millions, unless otherwise specified	Apr. 24, 2015	Apr. 25, 2014
Property Plant And Equipment [Abstract]
Computer software	$ 58.5us-gaap_CapitalizedComputerSoftwareNet	$ 103.5us-gaap_CapitalizedComputerSoftwareNet

The carrying amount of capitalized computer software costs net of accumulated amortization as of the balance sheet date.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 2

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128487-111756

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 985

-SubTopic 20

-Section 50

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6501960&loc=d3e128462-111756

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