Summary of Significant Accounting Policies - Additional Information (Detail)					3 Months Ended					12 Months Ended
	Nov. 20, 2019 USD ($)	Oct. 01, 2018 USD ($)	Jul. 31, 2018 USD ($)	Mar. 22, 2017 USD ($)	Sep. 28, 2019 USD ($) Customer	Mar. 30, 2019 USD ($)	Mar. 31, 2018 USD ($)	Sep. 30, 2017 USD ($)	Apr. 01, 2017	Sep. 28, 2019 USD ($) Customer	Sep. 29, 2018 USD ($) Customer	Sep. 30, 2017 USD ($)	Sep. 26, 2015 USD ($)	Dec. 11, 2017 USD ($)
Significant Accounting Policies [Line Items]
Proceeds from sale of business										$ 0	$ 0	$ 1,865,000,000.0
Impairment of intangible assets and equipment					$ 241,600,000	$ 443,800,000	$ 46,000,000.0			106,700,000	46,000,000.0	0
Goodwill impairment charge							685,700,000			$ 0	685,700,000	0
Cash Equivalents Maturity Period										three months or less
Gross Carrying Value					$ 4,786,600,000					$ 4,786,600,000	$ 5,571,800,000
Number of customers with balance greater than specified percentage | Customer					0					0	0
Accumulated Amortization					$ 3,326,800,000					$ 3,326,800,000	$ 3,173,200,000
Goodwill					2,563,700,000					2,563,700,000	2,533,200,000
Other-than-temporary impairment charges								$ 0
Purchase of interest rate caps										1,500,000	3,700,000	1,900,000	$ 13,200,000
Principal amount of borrowings					1,000,000,000.0					1,000,000,000.0
Loss reclassified from accumulated other comprehensive loss to the statement of operations, net										3,100,000	3,600,000	6,900,000
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred										2,300,000
Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments										11,000,000.0	1,300,000	3,100,000
Unrealized Gain (Loss) on Foreign Currency Derivatives, Net, before Tax										2,200,000	6,600,000	3,600,000
Notional Amount					104,200,000					$ 104,200,000
Product Warranty Term										1 year
Advertising cost										$ 29,500,000	26,900,000	22,500,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax										3,100,000	4,000,000.0
Increase to cash flows used in financing activities										280,700,000	195,200,000	(285,800,000)
Accelerated Depreciation											5,900,000	$ 3,000,000.0
Developed Technology Rights [Member]
Significant Accounting Policies [Line Items]
Gross Carrying Value					3,927,700,000					3,927,700,000	4,573,300,000
Accumulated Amortization					2,654,800,000					2,654,800,000	2,505,800,000
Trade Names [Member]
Significant Accounting Policies [Line Items]
Gross Carrying Value					245,400,000					245,400,000	312,500,000
Accumulated Amortization					171,100,000					171,100,000	175,000,000.0
In-process research and development
Significant Accounting Policies [Line Items]
Gross Carrying Value					0					0	5,500,000
Accumulated Amortization					0					$ 0	0
Minimum
Significant Accounting Policies [Line Items]
Intangible assets useful life										2 years
Transition services agreement term									2 years
Minimum | Accounts receivable [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage								10.00%		10.00%
Minimum | Total revenues [Member]
Significant Accounting Policies [Line Items]
Concentration risk, percentage								10.00%		10.00%		10.00%
Maximum
Significant Accounting Policies [Line Items]
Intangible assets useful life										30 years
Transition services agreement term									3 years
Equity Securities [Member]
Significant Accounting Policies [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax											400,000
Interest rate caps - derivative
Significant Accounting Policies [Line Items]
Interest rate caps - derivative					100,000					$ 100,000	7,700,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax										3,100,000	3,600,000
Focal Therapeutics
Significant Accounting Policies [Line Items]
Goodwill		$ 31,100,000
Focal Therapeutics | Developed Technology Rights [Member]
Significant Accounting Policies [Line Items]
Intangible assets		83,100,000
Focal Therapeutics | Trade Names [Member]
Significant Accounting Policies [Line Items]
Intangible assets		2,700,000
Focal Therapeutics | In-process research and development
Significant Accounting Policies [Line Items]
Intangible assets		$ 11,400,000
In process research and development reclassified to developed technology										5,500,000
Cynosure
Significant Accounting Policies [Line Items]
Goodwill impairment charge							685,700,000
Goodwill				$ 685,700,000
Cynosure | Developed Technology Rights [Member]
Significant Accounting Policies [Line Items]
Impairment charge							46,000,000.0
Cynosure | In-process research and development
Significant Accounting Policies [Line Items]
Intangible assets				$ 107,000,000.0
Cynosure | Goodwill [Member]
Significant Accounting Policies [Line Items]
Goodwill impairment charge							$ 685,700,000
Emsor
Significant Accounting Policies [Line Items]
Intangible assets														$ 4,600,000
Goodwill														$ 5,700,000
Faxitron
Significant Accounting Policies [Line Items]
Intangible assets											53,400,000
Goodwill			$ 45,600,000
Medical Aesthetics
Significant Accounting Policies [Line Items]
Goodwill					0					0	$ 0
Operating Segments [Member]
Significant Accounting Policies [Line Items]
Goodwill					$ 2,600,000,000					$ 2,600,000,000
Accounting Standards Update 2016-09 [Member]
Significant Accounting Policies [Line Items]
Increase to cash flows used in financing activities								$ 11,000,000				$ 10,700,000
Forward foreign currency contracts
Significant Accounting Policies [Line Items]
Derivative contract period, or less										1 year
Measurement Input, Discount Rate | Focal Therapeutics | Minimum | In-process research and development
Significant Accounting Policies [Line Items]
Fair value, discount rate		15.50%
Measurement Input, Discount Rate | Focal Therapeutics | Maximum | In-process research and development
Significant Accounting Policies [Line Items]
Fair value, discount rate		16.50%
Measurement Input, Discount Rate | Cynosure | Minimum | Other intangible assets
Significant Accounting Policies [Line Items]
Fair value, discount rate				11.00%
Measurement Input, Discount Rate | Cynosure | Minimum | In-process research and development
Significant Accounting Policies [Line Items]
Fair value, discount rate				14.00%
Measurement Input, Discount Rate | Cynosure | Maximum | Other intangible assets
Significant Accounting Policies [Line Items]
Fair value, discount rate				12.00%
Measurement Input, Discount Rate | Cynosure | Maximum | In-process research and development
Significant Accounting Policies [Line Items]
Fair value, discount rate				22.00%
Measurement Input, Discount Rate | Faxitron | Minimum | In-process research and development
Significant Accounting Policies [Line Items]
Fair value, discount rate			17.00%
Measurement Input, Discount Rate | Faxitron | Maximum | In-process research and development
Significant Accounting Policies [Line Items]
Fair value, discount rate			19.00%
Measurement Input, Discount Rate | Medical Aesthetics | Cynosure | Maximum | Other intangible assets
Significant Accounting Policies [Line Items]
Fair value, discount rate				12.00%
Subsequent Event | Medical Aesthetics Business
Significant Accounting Policies [Line Items]
Proceeds from sale of business	$ 205,000,000.0
Sales price	$ 138,000,000