Segment Information (Reconciliation Of Company's Consolidated Segment Operating Income To Consolidated Income Before Income Taxes) (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Oct. 02, 2020	Sep. 27, 2019	Oct. 02, 2020	Sep. 27, 2019
Segment Reporting Information [Line Items]
Consolidated operating income	$ 102.0	$ 91.7	$ 297.9	$ 287.7
Unallocated corporate expense	(337.7)	(330.3)	(988.5)	(1,033.2)
Restructuring charges / executive transition costs	(13.5)	(3.6)	(21.9)	(10.2)
COVID-19 expenses	(1.2)	0.0	(4.8)	0.0
Acquired deferred revenue adjustment	(0.7)	(0.4)	(4.0)	(4.3)
Amortization of purchased intangible assets	(40.0)	(40.8)	(120.2)	(128.6)
Stock-based compensation / deferred compensation	(32.0)	(18.5)	(61.9)	(55.9)
Amortization of acquired capitalized commissions	1.3	1.5	4.2	4.8
Acquisition / divestiture items	(3.7)	(8.4)	(16.4)	(11.5)
Non-operating expense, net	(5.6)	(12.8)	(31.2)	(18.2)
Consolidated income before taxes	96.4	78.9	266.7	269.5
Operating segment
Segment Reporting Information [Line Items]
Consolidated operating income	210.2	178.0	571.6	546.3
Corporate
Segment Reporting Information [Line Items]
Unallocated corporate expense	$ (18.4)	$ (16.1)	$ (48.7)	$ (52.9)

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