Income Taxes - Activity of Company's Unrecognized Income Tax Benefits (Detail) - USD ($) $ in Millions	12 Months Ended
Sep. 24, 2016	Sep. 26, 2015
Income Tax Disclosure [Abstract]
Balance at beginning of fiscal year	$ 154.7	$ 137.0
Tax positions related to current year:
Additions	23.9	11.0
Reductions	0.0	0.0
Tax positions related to prior years:
Additions related to change in estimate	1.1	21.1
Reductions	(6.9)	(10.3)
Payments	(6.0)	(0.8)
Lapses in statutes of limitations and settlements	(3.2)	(3.7)
Acquired tax positions:
Additions related to reserves acquired from acquisitions	0.0	0.4
Balance as of the end of the fiscal year	$ 163.6	$ 154.7

Tax positions related to current year.

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Tax positions related to prior years.

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Unrecognized tax benefits increases.

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

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

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Amount of decrease in unrecognized tax benefits resulting from settlements with taxing authorities.

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Amount of increase in unrecognized tax benefits resulting from acquisitions.

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

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

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

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