Income Taxes (Deferred Tax Assets and Liabilities) (Details) - USD ($) $ in Millions	Sep. 27, 2019	Sep. 28, 2018
Deferred tax assets:
Inventory	$ 10.1	$ 5.7
Bad debts	0.2	1.2
Accrued compensation and benefits	5.9	4.9
Product returns, allowances and warranty	0.3	4.6
Restructuring	0.6	0.0
Share-based and other deferred compensation	21.2	26.1
Net operating loss carry forwards	11.3	15.5
Federal tax credits	20.7	20.3
State tax credits	106.4	97.0
Deferred Tax Assets, Property, Plant and Equipment	17.7	9.1
Other - net	5.9	3.3
Deferred tax assets	200.3	187.7
Less valuation allowance	(129.1)	(118.6)
Net deferred tax assets	71.2	69.1
Deferred Tax Liabilities, Prepaid Expenses	0.5	0.6
Deferred tax liabilities:
Prepaid insurance	(6.3)	(2.0)
Property, plant and equipment	(19.3)	(25.6)
Intangible assets	(17.4)	(19.3)
Deferred Tax Liabilities, Net	43.5	47.5
Total deferred tax assets	$ 27.7	$ 21.6