Income Taxes - Narrative (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
Dec. 27, 2020	Dec. 29, 2019	Sep. 27, 2020	Sep. 29, 2019
Income Tax Disclosure [Abstract]
Effective tax rate	17.00%	21.10%
Reduction in income tax expense due to excess tax benefits on share-based payments	$ 6.1	$ 3.6
Effective tax rates, excluding impact of non-deductible goodwill impairment and transaction costs, excess tax benefits on share-based payments, TCJA, and valuation allowance release			26.80%	27.10%
Liability for uncertain tax positions	$ 10.7		$ 9.7

Effective Income Tax Rate Reconciliation, Excluding Impact Of Non-deductible Goodwill Impairment And Transaction Costs, Tax Benefits On Share-based Payments, TCJA, And Valuation Allowance, Percent

No definition available.

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- Definition

Amount recognized for uncertainty in income taxes.

+ References

No definition available.

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- Definition

Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

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- Definition

Amount of difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying domestic federal statutory income tax rate to pretax income (loss) from continuing operation, attributable to expense for award under share-based payment arrangement. Excludes expense determined to be nondeductible upon grant or after for award under share-based payment arrangement.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 740
-SubTopic 10
-Section 50
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=84230637&loc=d3e32687-109319

Reference 2: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 718
-SubTopic 740
-Section 35
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=120384911&loc=d3e23163-113944

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