Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Summary of Significant Accounting Policies - Intangible Assets and Goodwill (Details) - USD ($)	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018	Oct. 01, 2018
Finite-Lived Intangible Assets [Line Items]
Goodwill		$ 2,657,900,000	$ 2,563,700,000
Goodwill impairment charge	$ 685,700,000	0	$ 0	$ 685,700,000
Goodwill not at risk of failing impairment		$ 2,600,000,000
Focal Therapeutics
Finite-Lived Intangible Assets [Line Items]
Goodwill					$ 31,100,000