Borrowings and Credit Arrangements - Interest Expense Senior Notes (Details) - USD ($) $ in Millions	3 Months Ended
	Dec. 28, 2019	Dec. 29, 2018	Jan. 19, 2018
Line of Credit Facility [Line Items]
Interest expense	$ 15.7	$ 15.7
2025 Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate	4.375%
Senior Notes | 2028 Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate	4.625%		4.625%
Interest expense	$ 4.8	4.8
Senior Notes | 2025 Senior Notes
Line of Credit Facility [Line Items]
Stated interest rate	4.375%
Interest expense	$ 10.9	$ 10.9