Derivative Instruments and Hedging Activities - Effective Portion of Foreign Currency Forward Contracts Designated as Cash Flow Hedges (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Oct. 02, 2020	Jul. 03, 2020	Apr. 03, 2020	Jan. 03, 2020	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Oct. 02, 2020	Sep. 27, 2019	Sep. 28, 2018
Derivative [Line Items]
Revenues	$ 850.5	$ 694.3	$ 794.5	$ 828.9	$ 878.9	$ 825.8	$ 779.4	$ 741.0	$ 3,168.2	$ 3,225.1	$ 2,919.1
Amount gain (loss) reclassified from other comprehensive earnings (loss) into earnings									2.0	0.2	(0.6)
Revenues
Derivative [Line Items]
Revenues									3,168.2	3,225.1	2,919.1
Amount gain (loss) reclassified from other comprehensive earnings (loss) into earnings									2.6	0.2	(0.9)
Foreign currency forward contracts
Derivative [Line Items]
Foreign currency forward contracts									$ (0.3)	$ 3.0	$ (0.9)