Income Taxes - Components of Deferred Tax Assets (Liabilities) (Detail) - USD ($) $ in Millions	Oct. 01, 2017	Oct. 02, 2016
Income Tax Disclosure [Abstract]
Accounts receivable, net	$ 2.3	$ 2.1
Inventories	23.5	18.8
Accrued employee benefit expenses	4.0	10.0
Net operating losses	136.5	216.1
Tax credits	236.4	238.0
Accrued other expenses	16.0	10.3
Deferred equity compensation	20.7	20.0
Property and equipment, net	(6.6)	(4.4)
Debt issuance costs	17.3	20.9
Other assets	12.7	12.3
Total deferred tax assets	476.0	552.9
Intangible assets	(131.1)	(176.8)
Foreign declared dividend	(2.3)	(2.5)
Total deferred tax liabilities	(133.4)	(179.3)
Less valuation allowance	(379.2)	(456.4)
Deferred tax assets (liabilities), net	$ (36.6)	$ (82.8)