Goodwill and Intangible Assets - Gross Carrying Amount and Accumulated Amortization of Intangible Assets (Detail) (USD $) In Millions, unless otherwise specified	Apr. 03, 2015	Sep. 26, 2014
Finite Lived Intangible Assets [Line Items]
Accumulated amortization	$ (59.8)	$ (56.9)
Net carrying amount subject to amortization	36.2us-gaap_FiniteLivedIntangibleAssetsNet	38.9us-gaap_FiniteLivedIntangibleAssetsNet
Acquired existing technology
Finite Lived Intangible Assets [Line Items]
Finite lived intangible assets, gross	54.6	54.6
Patents, licenses and other
Finite Lived Intangible Assets [Line Items]
Finite lived intangible assets, gross	29.0	28.8
Customer contracts and supplier relationship
Finite Lived Intangible Assets [Line Items]
Finite lived intangible assets, gross	$ 12.4	$ 12.4

Accumulated amount of amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

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Amount before amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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Amount after amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life.

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