Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (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]
Revenue	$ 783.9	$ 795.2	$ 2,440.3	$ 2,322.9
Acquired deferred revenue adjustment	0.4	9.5	4.3	16.2
Amortization of acquired capitalized commissions	(1.5)	(1.8)	(4.8)	(2.9)
Consolidated segment operating income	91.7	77.4	287.7	231.1
Depreciation expense			29.7	26.2
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	179.1	183.6	546.8	528.9
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	784.3	804.7	2,444.6	2,339.1
Consolidated segment operating income	178.0	191.3	546.3	542.2
Depreciation expense	5.4	5.5	17.3	15.5
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	309.6	286.6	940.6	785.6
Acquired deferred revenue adjustment	0.2	9.2	3.8	15.1
Amortization of acquired capitalized commissions	(1.5)	(1.8)	(4.7)	(2.7)
Buildings and Infrastructure [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	83.0	60.9	229.7	171.8
Buildings and Infrastructure [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	309.8	295.8	944.4	800.7
Consolidated segment operating income	81.7	68.3	228.8	184.2
Depreciation expense	1.9	1.8	6.1	4.6
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	155.1	185.4	480.7	544.3
Acquired deferred revenue adjustment	0.0	0.0	0.0	0.0
Geospatial [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	30.6	47.4	91.1	126.3
Geospatial [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	155.1	185.4	480.7	544.3
Consolidated segment operating income	30.6	47.4	91.1	126.3
Depreciation expense	1.5	1.5	4.7	4.4
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	120.9	133.0	432.8	437.2
Acquired deferred revenue adjustment	0.2	0.2	0.5	0.8
Amortization of acquired capitalized commissions	0.0	0.0	(0.1)	(0.2)
Resources and Utilities [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	34.3	38.3	130.7	132.3
Resources and Utilities [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	121.1	133.2	433.3	438.0
Consolidated segment operating income	34.5	38.5	131.1	132.9
Depreciation expense	1.0	1.1	3.2	3.1
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	198.3	190.2	586.2	555.8
Acquired deferred revenue adjustment	0.0	0.1	0.0	0.3
Amortization of acquired capitalized commissions		0.0		0.0
Transportation [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	31.2	37.0	95.3	98.5
Transportation [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	198.3	190.3	586.2	556.1
Consolidated segment operating income	31.2	37.1	95.3	98.8
Depreciation expense	$ 1.0	$ 1.1	$ 3.3	$ 3.4

The amount of expense recognized in the current period for the periodic realization of capitalized fees that were paid to salespeople, distributors, brokers, and agents at the time of the conclusion of the sale. As a noncash expense, this element is added back to net income when calculating cash provided by or used in operations using the indirect method.

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