Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 28, 2018	Sep. 29, 2017
Deferred tax assets:
Inventory	$ 5.7	$ 7.4
Bad debts	1.2	0.1
Accrued compensation and benefits	4.9	7.1
Product returns, allowances and warranty	4.6	5.2
Restructuring	0.0	0.1
Intangible assets	0.0	10.6
Share-based and other deferred compensation	26.1	40.2
Net operating loss carry forwards	15.5	7.7
Federal tax credits	20.3	20.1
State tax credits	97.0	71.0
Deferred Tax Assets, Property, Plant and Equipment	9.1	7.9
Other - net	3.3	2.7
Deferred tax assets	187.7	180.1
Less valuation allowance	(118.6)	(90.9)
Net deferred tax assets	69.1	89.2
Deferred Tax Liabilities, Prepaid Expenses	0.6	0.9
Deferred tax liabilities:
Prepaid insurance	(2.0)	0.0
Property, plant and equipment	(25.6)	(24.8)
Intangible assets	(19.3)	(6.2)
Deferred Tax Liabilities, Net	47.5	31.9
Total deferred tax assets	$ 21.6	$ 57.3