Borrowings and Credit Arrangements - Interest Expense Credit Agreement (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 28, 2019	Sep. 29, 2018	Sep. 30, 2017	Sep. 24, 2016
Line of Credit Facility [Line Items]
Non-cash interest expense	$ 8.6	$ 15.0	$ 49.4
2018 Credit Agreement
Line of Credit Facility [Line Items]
Interest expense	67.0
Non-cash interest expense	$ 2.6
Weighted average interest rate	3.79%
Interest rate at end of period	3.43%
2017 Credit Agreement
Line of Credit Facility [Line Items]
Interest expense		60.8
Non-cash interest expense		$ 2.6
Weighted average interest rate		3.23%
Interest rate at end of period		3.74%
Prior Credit Agreement
Line of Credit Facility [Line Items]
Interest expense			42.3
Non-cash interest expense			$ 4.2
Weighted average interest rate			2.39%
Interest rate at end of period				2.73%