Segment Information (Reconciliation Of Company's Consolidated Segment Operating Income To Consolidated Income Before Income Taxes) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 27, 2019	Sep. 28, 2018	Sep. 27, 2019	Sep. 28, 2018
Segment Reporting Information [Line Items]
Consolidated operating income	$ 91.7	$ 77.4	$ 287.7	$ 231.1
Unallocated corporate expense	(330.3)	(349.5)	(1,033.2)	(1,014.7)
Restructuring charges	(3.6)	(2.6)	(10.2)	(6.8)
Acquired deferred revenue adjustment	(0.4)	(9.5)	(4.3)	(16.2)
Amortization of purchased intangible assets	(40.8)	(49.8)	(128.6)	(132.9)
Stock-based compensation	(18.6)	(18.8)	(52.1)	(53.1)
Amortization of acquired capitalized commissions	1.5	1.8	4.8	2.9
Acquisition / divestiture items	(8.4)	(10.7)	(11.5)	(34.8)
Non-operating expense, net	(12.8)	(13.3)	(18.2)	(21.1)
Consolidated income before taxes	78.9	64.1	269.5	210.0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated operating income	178.0	191.3	546.3	542.2
Corporate, Non-Segment [Member]
Segment Reporting Information [Line Items]
Unallocated corporate expense	$ (16.0)	$ (24.3)	$ (56.7)	$ (70.2)

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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Amount of income (loss) from continuing operations before deduction of income tax expense (benefit) and income (loss) attributable to noncontrolling interest, and addition of income (loss) from equity method investments.

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Amount, after cash payment, of expenses associated with exit or disposal activities pursuant to an authorized plan. Excludes expenses related to a discontinued operation or an asset retirement obligation.

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