Marketable Securities (Details) - USD ($) $ in Millions	12 Months Ended
Oct. 02, 2020	Sep. 27, 2019
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Noncurrent, Maximum Contractual Maturity	2 years
Debt Securities, Available-for-sale, Current	$ 408.1	$ 203.3
Debt Securities, Available-for-sale, Noncurrent	5.2	27.6
US Treasury and Government [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Current	129.4	34.2
Debt Securities, Available-for-sale, Noncurrent	5.0	20.0
Corporate Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Current	276.8	66.2
Debt Securities, Available-for-sale, Noncurrent	0.0	5.9
US States and Political Subdivisions Debt Securities [Member]
Debt Securities, Available-for-sale [Line Items]
Debt Securities, Available-for-sale, Current	1.9	102.9
Debt Securities, Available-for-sale, Noncurrent	$ 0.2	$ 1.7

Date of maturity of a debt security categorized as neither trading nor held to maturity, string text

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- Definition

Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as current.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=118942338&loc=SL82898722-210454

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=118954083&loc=d3e26626-111562

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Amount of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), classified as noncurrent.

+ References

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- Definition

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+ References

No definition available.

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