Segment Information (Reconciliation Of Company's Consolidated Segment Operating Income To Consolidated Income Before Income Taxes) (Detail) - USD ($) $ in Millions	3 Months Ended
Apr. 03, 2020	Mar. 29, 2019
Segment Reporting Information [Line Items]
Consolidated operating income	$ 98.3	$ 86.3
Unallocated corporate expense	(342.7)	(352.0)
Restructuring charges	(3.2)	(3.7)
COVID-19 expenses	(3.8)
Acquired deferred revenue adjustment	(1.7)	(2.9)
Amortization of purchased intangible assets	(40.4)	(44.3)
Stock-based compensation and deferred compensation	(4.5)	(19.1)
Amortization of acquired capitalized commissions	1.5	1.7
Acquisition / divestiture items	(10.8)	(1.1)
Non-operating expense, net	(18.9)	(11.1)
Consolidated income before taxes	79.4	75.2
Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated operating income	175.1	174.2
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expense	$ (13.9)	$ (18.5)

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The aggregate amount of recurring noncash expense charged against earnings in the period to allocate the cost of assets over their estimated remaining economic lives.

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