Business Combinations - Narrative (Details) - USD ($) $ / shares in Units, shares in Millions									1 Months Ended		2 Months Ended	3 Months Ended				12 Months Ended
	Aug. 23, 2020	Dec. 30, 2019	Nov. 21, 2019	Oct. 01, 2019	Aug. 01, 2019	Oct. 01, 2018	Jul. 31, 2018	Dec. 11, 2017	Nov. 30, 2019	Sep. 30, 2019	Sep. 28, 2019	Sep. 26, 2020	Jun. 27, 2020	Mar. 28, 2020	Dec. 28, 2019	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018	Nov. 20, 2019	Mar. 30, 2019
Business Acquisition [Line Items]
Intangible assets											$ 1,459,800,000	$ 1,307,500,000				$ 1,307,500,000	$ 1,459,800,000
Goodwill											2,563,700,000	2,657,900,000				2,657,900,000	2,563,700,000
Portion allocable to fair value of noncontrolling interest			$ 8,600,000
Payment of contingent holdbacks																24,300,000	6,500,000	$ 0
Acessa
Business Acquisition [Line Items]
Total purchase price	$ 161,300,000
Contingent consideration	$ 81,800,000
Fair value discount rate (percent)	18.00%
Weighted average amortization period	10 years
Goodwill	$ 48.4
Acessa | Holdback
Business Acquisition [Line Items]
Contingent consideration	$ 3,000,000.0
Payment period for contingent consideration	5 months
Acessa | Developed technology
Business Acquisition [Line Items]
Identifiable intangible assets:	$ 127.0
Acessa | Trade names
Business Acquisition [Line Items]
Identifiable intangible assets:	$ 1.2
Health Beacons
Business Acquisition [Line Items]
Total purchase price													$ 19,700,000
Holdback												2,300,000				2,300,000
Intangible assets												10,700,000				10,700,000
Goodwill												6,200,000				6,200,000
Acquired tangible assets and liabilities												2,800,000				2,800,000
Alpha Imaging
Business Acquisition [Line Items]
Total purchase price		$ 18,000,000.0
Contingent consideration												$ 900,000				$ 900,000
Holdback											1,000,000.0						$ 1,000,000.0
SuperSonic Imagine
Business Acquisition [Line Items]
Total purchase price			69,300,000		$ 18,200,000
Fair value discount rate (percent)																	12.00%
Goodwill			34,300,000
Identifiable intangible assets			$ 4,000,000.0
Percentage of voting interests acquired					46.00%														50.00%
Cash tender offer price per share										$ 1.50
Acquired shares			7.6
Ownership of outstanding shares (as a percent)			78.00%
Equity interest in acquiree (as a percent)					46.00%							81.00%				81.00%
Remeasurement gain			$ 3,200,000
Portion allocable to equity method investment			17,900,000
Portion allocable to newly acquired shares									$ 12,600,000
Portion allocable to loan repaymnet			30,200,000
Additional purchase consideration			$ 12,600,000
Additional outstanding shares purchased (in shares)																1.1
Additional outstanding shares purchased, amount																$ 1,800,000
SuperSonic Imagine | Other Income
Business Acquisition [Line Items]
Income (loss) from equity method investments											$ 3,300,000
SuperSonic Imagine | Developed technology
Business Acquisition [Line Items]
Weighted average amortization period			9 years
SuperSonic Imagine | Customer relationships
Business Acquisition [Line Items]
Weighted average amortization period			9 years
SuperSonic Imagine | Trade names
Business Acquisition [Line Items]
Weighted average amortization period			8 years 7 months 6 days
Focal Therapeutics
Business Acquisition [Line Items]
Total purchase price				$ 12,500,000		$ 120,100,000
Contingent consideration						$ 14,000,000.0														$ 1,500,000
Payment period for contingent consideration						1 year
Goodwill						$ 31,100,000
Focal Therapeutics | In-process research and development
Business Acquisition [Line Items]
Identifiable intangible assets:						$ 11,400,000
Focal Therapeutics | In-process research and development | Measurement Input, Discount Rate | Minimum
Business Acquisition [Line Items]
Fair value discount rate (percent)						15.50%
Focal Therapeutics | In-process research and development | Measurement Input, Discount Rate | Maximum
Business Acquisition [Line Items]
Fair value discount rate (percent)						16.50%
Focal Therapeutics | Developed technology
Business Acquisition [Line Items]
Weighted average amortization period						11 years
Identifiable intangible assets:						$ 83,100,000
Focal Therapeutics | Trade names
Business Acquisition [Line Items]
Weighted average amortization period						13 years
Identifiable intangible assets:						$ 2,700,000
Faxitron
Business Acquisition [Line Items]
Total purchase price							$ 89,500,000
Contingent consideration							2,900,000
Goodwill							45,600,000
Increase in contingent consideration liability												$ 1,700,000
Payment of contingent holdbacks														$ 5,000,000.0
Payment of contingent consideration															$ 4,100,000
Faxitron | Holdback
Business Acquisition [Line Items]
Contingent consideration							$ 11,700,000
Payment period for contingent consideration							1 year
Payment of contingent holdbacks																6,500,000
Contingent holdback withheld under indemnification provisions																$ 5,200,000
Faxitron | In-process research and development | Measurement Input, Discount Rate | Minimum
Business Acquisition [Line Items]
Fair value discount rate (percent)							17.00%
Faxitron | In-process research and development | Measurement Input, Discount Rate | Maximum
Business Acquisition [Line Items]
Fair value discount rate (percent)							19.00%
Faxitron | Customer relationships
Business Acquisition [Line Items]
Weighted average amortization period							9 years
Faxitron | Trade names
Business Acquisition [Line Items]
Weighted average amortization period							7 years
Emsor
Business Acquisition [Line Items]
Total purchase price								$ 16,300,000
Contingent consideration								4,900,000
Goodwill								5,700,000
Identifiable intangible assets:								4,600,000
Tangible assets and liabilities								$ 6,000,000.0
Emsor | Holdback
Business Acquisition [Line Items]
Payment period for contingent consideration								2 years