Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 29, 2019	Mar. 30, 2018
Segment Reporting Information [Line Items]
Revenue	$ 801.6	$ 742.2
Acquired deferred revenue adjustment	2.9	2.9
Amortization of acquired capitalized commissions	(1.7)	(0.5)
Consolidated segment operating income	86.3	64.2
Depreciation expense	10.2	8.5
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	173.0	162.9
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	804.5	745.1
Consolidated segment operating income	174.2	165.3
Depreciation expense	5.9	4.9
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	292.0	224.7
Acquired deferred revenue adjustment	2.7	2.5
Amortization of acquired capitalized commissions	(1.6)	(0.4)
Buildings and Infrastructure [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	61.4	43.5
Buildings and Infrastructure [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	294.7	227.2
Consolidated segment operating income	62.5	45.6
Depreciation expense	2.1	1.4
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	161.2	174.5
Acquired deferred revenue adjustment	0.0	0.0
Geospatial [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	29.4	37.3
Geospatial [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	161.2	174.5
Consolidated segment operating income	29.4	37.3
Depreciation expense	1.6	1.4
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	159.3	159.2
Acquired deferred revenue adjustment	0.2	0.3
Amortization of acquired capitalized commissions	(0.1)	(0.1)
Resources and Utilities [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	51.0	51.7
Resources and Utilities [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	159.5	159.5
Consolidated segment operating income	51.1	51.9
Depreciation expense	1.1	1.0
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	189.1	183.8
Acquired deferred revenue adjustment	0.0	0.1
Amortization of acquired capitalized commissions		0.0
Transportation [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	31.2	30.4
Transportation [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	189.1	183.9
Consolidated segment operating income	31.2	30.5
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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