Income Taxes - Provision for Income Taxes (Detail) - USD ($) $ in Millions	12 Months Ended
	Oct. 01, 2017	Oct. 02, 2016	Sep. 27, 2015
Income Tax Disclosure [Abstract]
Federal	$ 0.8	$ 0.0	$ 0.0
State	0.6	0.2	0.2
Foreign	12.2	4.3	4.2
Federal	2.5	4.1	4.6
State	0.4	0.2	0.0
Foreign	(56.7)	(1.6)	3.3
Income Tax Expense (Benefit)	$ (40.2)	$ 7.2	$ 12.3