Summary of Significant Accounting Policies - Additional Information (Detail)			3 Months Ended							12 Months Ended
	Oct. 01, 2018 USD ($)	Jul. 31, 2018 USD ($)	Sep. 26, 2020 USD ($) Customer	Mar. 28, 2020 USD ($)	Dec. 28, 2019 USD ($)	Mar. 30, 2019 USD ($)	Dec. 29, 2018 USD ($)	Sep. 29, 2018	Mar. 31, 2018 USD ($)	Sep. 26, 2020 USD ($) Customer	Sep. 28, 2019 USD ($) Customer	Sep. 29, 2018 USD ($)	Dec. 11, 2017 USD ($)
Significant Accounting Policies [Line Items]
Net proceeds from sale of business										$ 139,300,000	$ 0	$ 0
Impairment of intangible assets and equipment			$ 241,600,000	$ 443,800,000	$ 30,200,000					4,400,000	106,700,000	46,000,000.0
Impairment charge					$ 30,200,000	$ 685,400,000
Goodwill impairment charge									$ 685,700,000	$ 0	0	685,700,000
Cash Equivalents Maturity Period										three months or less
Gross Carrying Value			$ 4,931,100,000							$ 4,931,100,000	$ 4,786,600,000
Number of customers with balance greater than specified percentage | Customer			1							1	0
Accumulated Amortization			$ 3,623,600,000							$ 3,623,600,000	$ 3,326,800,000
Goodwill			2,657,900,000							2,657,900,000	2,563,700,000
Purchase of interest rate caps							$ 3,700,000			0	1,500,000	3,700,000
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										2,300,000	3,100,000	3,600,000
Derivative Instruments, Gain (Loss) Reclassification from Accumulated OCI to Income, Estimated Net Amount to be Transferred										500,000
Notional Amount			172,600,000							$ 172,600,000
Product Warranty Term										1 year
Advertising cost										$ 15,600,000	29,500,000	26,900,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax										2,300,000	3,100,000
Increase to cash flows used in financing activities										141,600,000	280,700,000	195,200,000
Goodwill and Intangible Asset Impairment											685,400,000
Notional amount			1,000,000,000.0							1,000,000,000.0
(Loss) gain recognized, net of tax of $(8.3) million in 2020 and $1.2 million in 2019 for interest rate swaps										(500,000)	(8,000,000.0)
Trade names
Significant Accounting Policies [Line Items]
Gross Carrying Value			245,500,000							245,500,000	245,400,000
Accumulated Amortization			181,200,000							181,200,000	171,100,000
Developed technology
Significant Accounting Policies [Line Items]
Gross Carrying Value			4,054,000,000.0							4,054,000,000.0	3,927,700,000
Accumulated Amortization			2,907,200,000							$ 2,907,200,000	$ 2,654,800,000
Minimum
Significant Accounting Policies [Line Items]
Intangible assets useful life										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
Interest rate caps - derivative
Significant Accounting Policies [Line Items]
Interest rate caps - derivative			0.0							$ 0.0	$ 100,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax										2,300,000	3,100,000
Interest Rate Swap [Member]
Significant Accounting Policies [Line Items]
Interest rate caps - derivative			31,200,000							31,200,000
Notional Amount			380,200,000							380,200,000
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax										0	0
(Loss) gain recognized, net of tax of $(8.3) million in 2020 and $1.2 million in 2019 for interest rate swaps										(27,600,000)	3,500,000	$ 0
Focal Therapeutics
Significant Accounting Policies [Line Items]
Goodwill	$ 31,100,000
Focal Therapeutics | Trade names
Significant Accounting Policies [Line Items]
Identifiable intangible assets:	2,700,000
Focal Therapeutics | Developed technology
Significant Accounting Policies [Line Items]
Identifiable intangible assets:	83,100,000
Focal Therapeutics | In-process research and development
Significant Accounting Policies [Line Items]
Identifiable intangible assets:	$ 11,400,000
In process research and development reclassified to developed technology											$ 5,500,000
Emsor
Significant Accounting Policies [Line Items]
Identifiable intangible assets:													$ 4,600,000
Goodwill													$ 5,700,000
Faxitron
Significant Accounting Policies [Line Items]
Goodwill		$ 45,600,000
Acessa Health [Member] | Trade names
Significant Accounting Policies [Line Items]
Identifiable intangible assets:			1,200,000							1,200,000
Acessa Health [Member] | Developed technology
Significant Accounting Policies [Line Items]
Identifiable intangible assets:			127,000,000.0							$ 127,000,000.0
Medical Aesthetics
Significant Accounting Policies [Line Items]
Impairment charge				30,200,000
Medical Aesthetics | In-process research and development
Significant Accounting Policies [Line Items]
Impairment charge									$ 46,000,000.0
Medical Aesthetics | Distribution agreement [Member]
Significant Accounting Policies [Line Items]
Impairment charge			27,700,000	1,200,000
Medical Aesthetics | Customer relationships
Significant Accounting Policies [Line Items]
Impairment charge			22,400,000	900,000
Medical Aesthetics | Trade names
Significant Accounting Policies [Line Items]
Impairment charge			48,600,000	2,000,000.0
Medical Aesthetics | Developed Technology [Member]
Significant Accounting Policies [Line Items]
Impairment charge			576,900,000	$ 24,100,000
Medical Aesthetics | Property, Plant and Equipment [Member]
Significant Accounting Policies [Line Items]
Impairment charge			$ 9,800,000
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 | 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%