Business Combinations (Details) $ / shares in Units, $ in Billions			1 Months Ended		3 Months Ended				12 Months Ended
	Jun. 14, 2018 USD ($)	Jan. 30, 2018 AUD ($) $ / shares	Aug. 31, 2019 USD ($)	Jun. 28, 2019 USD ($)	Sep. 27, 2019 USD ($)	Jun. 28, 2019 USD ($)	Dec. 28, 2018 USD ($)	Jun. 29, 2018 USD ($)	Sep. 27, 2019 USD ($)	Sep. 28, 2018 USD ($) company	Sep. 29, 2017 USD ($)	May 04, 2018 $ / shares
Business Acquisition [Line Items]
Change in fair value of contingent consideration					$ 18,600,000		$ 11,600,000		$ 18,600,000	$ 0	$ 300,000
IPR&D expensed						$ 20,800,000			20,800,000	0	0
Goodwill acquired									372,300,000	$ 72,100,000
Measurement period adjustment to reduce FV of purchase price consideration					2,600,000		(9,600,000)
Measurement period adjustment to decrease finite-lived intangible assets							(5,400,000)
Measurement period adjustment to decrease goodwill							$ (4,800,000)		(2,200,000)
Breakup fee from Sirtex								$ 9,000,000.0
Number of companies acquired | company										4
Goodwill					612,200,000				612,200,000	$ 293,600,000	222,600,000
Business combination, acquisition related costs									23,400,000	$ 6,700,000	$ 1,700,000
Embolics Microspheres Business
Business Acquisition [Line Items]
Cash paid			$ 90,000,000.0
Contingent liability owed to a third party			16,000,000.0
Indemnification assets			$ 16,000,000.0
Finite-lived intangible assets					37,800,000				37,800,000
Goodwill					45,800,000				45,800,000
Privately-held Company
Business Acquisition [Line Items]
Asset acquisition, purchase price						15,200,000
Asset acquisition, holdback amount						3,600,000
Asset acquisition, fair value of contingent consideration				$ 0		0
Asset acquisition, potential maximum payout of contingent consideration						9,000,000
Privately-held Software Company
Business Acquisition [Line Items]
Acquisition purchase price									28,500,000
Goodwill acquired									21,900,000
Finite-lived intangible assets					6,500,000				6,500,000
Cancer Treatment Services International
Business Acquisition [Line Items]
Cash paid				262,800,000
Acquisition purchase price				277,000,000.0
Contingent consideration					8,200,000				8,200,000
Other consideration				6,000,000.0
Undiscounted range of contingent consideration payments, low				0
Undiscounted range of contingent consideration payments, high				$ 58,000,000
Revenue projection period for consideration payments				18 months
Additional contingent consideration					3,300,000				3,300,000
Finite-lived intangible assets					111,800,000				111,800,000
Goodwill					186,100,000				186,100,000
Endocare and Alicon
Business Acquisition [Line Items]
Cash paid				$ 197,400,000
Acquisition purchase price				210,000,000.0
Contingent consideration					12,600,000				12,600,000
Undiscounted range of contingent consideration payments, low				0
Undiscounted range of contingent consideration payments, high				$ 40,000,000
Change in fair value of contingent consideration									18,600,000
Finite-lived intangible assets					64,100,000				64,100,000
Goodwill					$ 118,500,000				$ 118,500,000
Sirtex Medical Limited
Business Acquisition [Line Items]
Cash paid		$ 1.6
Acquisition share price (in AUD per share) | $ / shares		$ 28
Competing bid for Sirtex made by CDH Investments ( in AUD per share) | $ / shares												$ 33.60
Breakup fee from Sirtex	$ 9,000,000.0
Privately-held Software Companies
Business Acquisition [Line Items]
Number of companies acquired | company										2
Fiscal Year 2018 Acquisitions
Business Acquisition [Line Items]
Cash paid										$ 109,000,000.0
Acquisition purchase price										136,700,000
Finite-lived intangible assets										49,900,000
Goodwill										72,100,000
Goodwill deductible for income tax purposes										$ 14,000,000
Acquisition-related Expenses
Business Acquisition [Line Items]
IPR&D expensed						$ 20,800,000