Summary of Significant Accounting Policies - Changes in accumulated balances of other comprehensive income (Details) - USD ($) $ in Millions	12 Months Ended
	Sep. 29, 2018	Sep. 30, 2017	Sep. 24, 2016
Accumulated Other Comprehensive Income (Loss) [Line Items]
Accumulated Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Net of Tax	$ (26.6)	$ (18.5)	$ (26.1)
Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	0.0	(0.4)	(0.3)
Accumulated Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax	(1.1)	(1.6)	(2.5)
Accumulated other comprehensive Income loss Hedge	2.2	4.3	(3.4)
Accumulated Other Comprehensive Income (Loss), Net of Tax	(25.5)	(16.2)	(32.3)
Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Portion Attributable to Parent	(8.1)	7.6	(10.4)
Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax	0.0	2.3	(1.1)
Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent	(0.5)	(0.9)	$ 0.7
Derivative Instruments, Gain (Loss) Recognized in Other Comprehensive Income (Loss), Effective Portion, Net	(5.7)	0.8
Other Comprehensive Income (Loss), before Reclassifications, before Tax	(13.3)	11.6
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	4.0	4.5
Accumulated Foreign Currency Adjustment Attributable to Parent [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.0	0.0
Pension in Accumulated Other Comprehensive Income [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.0	0.0
Equity Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	0.4	(2.4)
Interest Rate Cap [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax	$ 3.6	$ 6.9