Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 28, 2019	Jun. 29, 2018	Jun. 28, 2019	Jun. 29, 2018
Segment Reporting Information [Line Items]
Revenue	$ 854.8	$ 785.5	$ 1,656.4	$ 1,527.7
Acquired deferred revenue adjustment	1.0	3.8	3.9	6.7
Amortization of acquired capitalized commissions	(1.6)	(0.6)	(3.3)	(1.1)
Consolidated segment operating income	109.7	89.5	196.0	153.7
Depreciation expense			20.3	17.2
Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	194.7	182.4	367.7	345.3
Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	855.8	789.3	1,660.3	1,534.4
Consolidated segment operating income	194.1	185.6	368.3	350.9
Depreciation expense	6.0	5.1	11.9	10.0
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	339.0	274.3	631.0	499.0
Acquired deferred revenue adjustment	0.9	3.4	3.6	5.9
Amortization of acquired capitalized commissions	(1.6)	(0.5)	(3.2)	(0.9)
Buildings and Infrastructure [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	85.3	67.4	146.7	110.9
Buildings and Infrastructure [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	339.9	277.7	634.6	504.9
Consolidated segment operating income	84.6	70.3	147.1	115.9
Depreciation expense	2.1	1.4	4.2	2.8
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	164.4	184.4	325.6	358.9
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	31.1	41.6	60.5	78.9
Geospatial [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	164.4	184.4	325.6	358.9
Consolidated segment operating income	31.1	41.6	60.5	78.9
Depreciation expense	1.6	1.5	3.2	2.9
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	152.6	145.0	311.9	304.2
Acquired deferred revenue adjustment	0.1	0.3	0.3	0.6
Amortization of acquired capitalized commissions	0.0	(0.1)	(0.1)	(0.2)
Resources and Utilities [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	45.4	42.3	96.4	94.0
Resources and Utilities [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	152.7	145.3	312.2	304.8
Consolidated segment operating income	45.5	42.5	96.6	94.4
Depreciation expense	1.1	1.0	2.2	2.0
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	198.8	181.8	387.9	365.6
Acquired deferred revenue adjustment	0.0	0.1	0.0	0.2
Amortization of acquired capitalized commissions		0.0		0.0
Transportation [Member] \| Segment Reconciling Items [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	32.9	31.1	64.1	61.5
Transportation [Member] \| Operating Segments [Member]
Segment Reporting Information [Line Items]
Segment Revenues	198.8	181.9	387.9	365.8
Consolidated segment operating income	32.9	31.2	64.1	61.7
Depreciation expense	$ 1.2	$ 1.2	$ 2.3	$ 2.3

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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