Income Taxes - Reconciliation of the Unrecognized Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 27, 2015	Sep. 28, 2014	Sep. 29, 2013
Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward]
Beginning gross unrecognized tax benefits	$ 97.7	$ 69.6	$ 58.0
Additions based on tax positions related to the current year	3.5	2.4	3.2
Additions based on current year acquisitions	16.2	28.9	0.0
Additions based on tax positions of prior years	4.8	0.4	12.9
Unrecognized Tax Benefits, Decreases Resulting from Prior Period Tax Positions	0.0	0.0	(2.8)
Reductions for lapses and settlements	(0.4)	(3.6)	(1.7)
Ending gross unrecognized tax benefit	$ 121.8	$ 97.7	$ 69.6

Unrecognized Tax Benefits, Increase, Resulting from Acquisitions

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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- Definition

Amount of unrecognized tax benefits pertaining to uncertain tax positions taken in tax returns.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

-Paragraph 15A

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6907707&loc=SL6600010-109319

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

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Unrecognized Tax Benefit

-URI http://asc.fasb.org/extlink&oid=6527854

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- Definition

Amount of decrease in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions that have been or will be taken in current period tax return.

+ References

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- Definition

Amount of increase in unrecognized tax benefits resulting from tax positions taken in prior period tax returns.

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- Definition

Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations.

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