Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Detail) - USD ($) $ in Millions	3 Months Ended
Apr. 03, 2020	Mar. 29, 2019
Segment Reporting Information [Line Items]
Revenue	$ 792.3	$ 801.6
Acquired deferred revenue adjustment	1.7	2.9
Amortization of acquired capitalized commissions	(1.5)	(1.7)
Consolidated segment operating income	98.3	86.3
Depreciation expense	9.8	10.2
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	174.9	173.0
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	794.0	804.5
Consolidated segment operating income	175.1	174.2
Depreciation expense	5.9	5.9
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	296.8	292.0
Acquired deferred revenue adjustment	0.1	2.7
Amortization of acquired capitalized commissions	(1.4)	(1.6)
Buildings and Infrastructure [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	62.1	61.4
Buildings and Infrastructure [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	296.9	294.7
Consolidated segment operating income	60.8	62.5
Depreciation expense	2.1	2.1
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	146.2	161.2
Acquired deferred revenue adjustment	0.0	0.0
Geospatial [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	30.5	29.4
Geospatial [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	146.2	161.2
Consolidated segment operating income	30.5	29.4
Depreciation expense	1.4	1.6
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	179.0	159.3
Acquired deferred revenue adjustment	1.3	0.2
Amortization of acquired capitalized commissions	0.0	(0.1)
Resources and Utilities [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	65.6	51.0
Resources and Utilities [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	180.3	159.5
Consolidated segment operating income	66.9	51.1
Depreciation expense	1.3	1.1
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	170.3	189.1
Acquired deferred revenue adjustment	0.3	0.0
Amortization of acquired capitalized commissions	(0.1)	0.0
Transportation [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	16.7	31.2
Transportation [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	170.6	189.1
Consolidated segment operating income	16.9	31.2
Depreciation expense	$ 1.1	$ 1.1

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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