Summary of Significant Accounting Policies - Adjustments from Amounts Previously Reported (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 27, 2019	Sep. 28, 2018	Sep. 29, 2017
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities	$ (631.7)	$ (174.7)	$ (130.4)
Cash and cash equivalents at beginning of period	516.4	718.5	846.1
Cash, cash equivalents and restricted cash at end of period	544.1	516.4	718.5
As Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities		(184.0)	(130.1)
Cash and cash equivalents at beginning of period	504.8	716.2	843.5
Cash, cash equivalents and restricted cash at end of period		504.8	716.2
Accounting Standards Update 2016-18 | Adjustments
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Net cash used in investing activities		9.3	(0.3)
Cash and cash equivalents at beginning of period	$ 11.6	2.3	2.6
Cash, cash equivalents and restricted cash at end of period		$ 11.6	$ 2.3