Income Taxes (Schedule Of Deferred Tax Assets And Liabilities) (Details) - USD ($) $ in Millions	Dec. 29, 2017	Dec. 30, 2016
Income Tax Disclosure [Abstract]
Purchased intangibles	$ 69.8	$ 91.9
Depreciation and amortization	13.1	11.7
US residual tax on foreign earnings	0.0	11.3
Total deferred tax liabilities	82.9	114.9
Inventory valuation differences	4.6	12.9
Expenses not currently deductible	18.1	27.7
US federal tax credit carryforwards	0.2	0.3
Deferred revenue	5.8	6.9
US state tax credit carryforwards	21.7	15.1
Accrued warranty	2.0	3.1
US federal net operating loss carryforwards	6.4	3.8
Foreign net operating loss carryforwards	20.2	31.2
Stock-based compensation	21.5	31.9
Deferred Tax Liabilities, Other	(4.4)
Other		4.1
Total deferred tax assets	96.1	137.0
Valuation allowance	(25.2)	(30.6)
Total deferred tax assets	70.9	106.4
Total deferred tax liabilities	(12.0)	(8.5)
Non-current deferred income tax assets	28.4	30.3
Non-current deferred income tax liabilities	$ (40.4)	$ (38.8)