Summary of Significant Accounting Policies - Gain (Loss) on Fair Value Hedges Recognized in Earnings (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 26, 2020	Sep. 28, 2019	Sep. 29, 2018
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 2.6	$ 8.9	$ 5.3
Forward foreign currency contracts
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	0.5	8.8	5.3
Foreign Exchange Option
Derivative Instruments, Gain (Loss) [Line Items]
Gain (Loss) on Fair Value Hedges Recognized in Earnings	$ 2.1	$ 0.1	$ 0.0