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Business Combinations (Details) $ / shares in Units, $ in Billions			3 Months Ended	12 Months Ended
	Jun. 14, 2018 USD ($)	Jan. 30, 2018 AUD ($) $ / shares	Jun. 29, 2018 USD ($)	Sep. 28, 2018 USD ($) company	Sep. 29, 2017 USD ($)	Sep. 30, 2016 USD ($)	May 04, 2018 $ / shares
Business Acquisition [Line Items]
Loss related to hedging the anticipated Australian dollar purchase price for Sirtex				$ 5,500,000	$ 0	$ 0
Breakup fee from Sirtex			$ 9,000,000
Number of companies acquired \| company				4
Goodwill				$ 293,600,000	222,600,000	220,000,000
Goodwill deductible for income tax purposes				14,000,000		0
Other payments				36,400,000	$ 1,900,000	3,100,000
Acquisition costs			$ 8,400,000	15,700,000
Sirtex Medical Limited
Business Acquisition [Line Items]
Loss related to hedging the anticipated Australian dollar purchase price for Sirtex				$ 29,700,000
Acquisition share price (in AUD per share) \| $ / shares		$ 28
Cash paid		$ 1.6
Competing bid for Sirtex made by CDH Investments ( in AUD per share) \| $ / shares							$ 33.60
Breakup fee from Sirtex	$ 9,000,000
Privately-held Software Companies
Business Acquisition [Line Items]
Number of companies acquired \| company				2
Fiscal Year 2018 Acquisitions
Business Acquisition [Line Items]
Cash paid				$ 109,000,000
Goodwill				72,100,000
Finite-lived intangible assets				$ 49,900,000
Privately-held Distributor of Radiotherapy Equipment
Business Acquisition [Line Items]
Cash paid						35,200,000
Goodwill						11,400,000
Finite-lived intangible assets						$ 24,900,000