Borrowings and Credit Arrangements - Interest Expense Senior Notes (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Mar. 27, 2021	Mar. 28, 2020	Mar. 27, 2021	Mar. 28, 2020	Sep. 28, 2020
Line of Credit Facility [Line Items]
Interest expense	$ 13.1	$ 15.7	$ 28.2	$ 31.4
Senior Notes | 2028 Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate	4.625%		4.625%
Interest expense	$ 4.8	4.8	$ 9.6	9.6
Senior Notes | 2025 Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate	4.375%		4.375%
Interest expense	$ 0.0	10.9	$ 2.3	21.8
Senior Notes | 2029 Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate	3.25%		3.25%		3.25%
Interest expense	$ 8.3	$ 0.0	$ 16.3	$ 0.0