Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Oct. 02, 2020	Sep. 27, 2019	Oct. 02, 2020	Sep. 27, 2019
Segment Reporting Information [Line Items]
Revenue	$ 792.1	$ 783.9	$ 2,318.0	$ 2,440.3
Acquired deferred revenue adjustment	0.7	0.4	4.0	4.3
Segment revenue	792.8	784.3	2,322.0	2,444.6
Amortization of acquired capitalized commissions	(1.3)	(1.5)	(4.2)	(4.8)
Consolidated segment operating income	102.0	91.7	297.9	287.7
Depreciation expense			29.4	29.7
Segment Reconciling
Segment Reporting Information [Line Items]
Consolidated segment operating income	210.8	179.1	571.8	546.8
Operating segment
Segment Reporting Information [Line Items]
Consolidated segment operating income	210.2	178.0	571.6	546.3
Depreciation expense	5.9	5.4	17.7	17.3
Buildings and Infrastructure
Segment Reporting Information [Line Items]
Revenue	317.4	309.6	909.4	940.6
Acquired deferred revenue adjustment	0.0	0.2	0.2	3.8
Segment revenue	317.4	309.8	909.6	944.4
Amortization of acquired capitalized commissions	(1.3)	(1.5)	(4.0)	(4.7)
Buildings and Infrastructure | Segment Reconciling
Segment Reporting Information [Line Items]
Consolidated segment operating income	97.2	83.0	245.9	229.7
Buildings and Infrastructure | Operating segment
Segment Reporting Information [Line Items]
Consolidated segment operating income	95.9	81.7	242.1	228.8
Depreciation expense	2.0	1.9	6.1	6.1
Geospatial
Segment Reporting Information [Line Items]
Revenue	165.6	155.1	457.0	480.7
Acquired deferred revenue adjustment	0.0	0.0	0.0	0.0
Segment revenue	165.6	155.1	457.0	480.7
Amortization of acquired capitalized commissions	0.0	0.0	0.0	0.0
Geospatial | Segment Reconciling
Segment Reporting Information [Line Items]
Consolidated segment operating income	51.4	30.6	119.3	91.1
Geospatial | Operating segment
Segment Reporting Information [Line Items]
Consolidated segment operating income	51.4	30.6	119.3	91.1
Depreciation expense	1.5	1.5	4.4	4.7
Resources and Utilities
Segment Reporting Information [Line Items]
Revenue	150.2	120.9	472.1	432.8
Acquired deferred revenue adjustment	0.4	0.2	2.6	0.5
Segment revenue	150.6	121.1	474.7	433.3
Amortization of acquired capitalized commissions	0.0	0.0	(0.1)	(0.1)
Resources and Utilities | Segment Reconciling
Segment Reporting Information [Line Items]
Consolidated segment operating income	53.9	34.3	167.8	130.7
Resources and Utilities | Operating segment
Segment Reporting Information [Line Items]
Consolidated segment operating income	54.3	34.5	170.3	131.1
Depreciation expense	1.5	1.0	4.1	3.2
Transportation
Segment Reporting Information [Line Items]
Revenue	158.9	198.3	479.5	586.2
Acquired deferred revenue adjustment	0.3	0.0	1.2	0.0
Segment revenue	159.2	198.3	480.7	586.2
Amortization of acquired capitalized commissions	0.0	0.0	(0.1)	0.0
Transportation | Segment Reconciling
Segment Reporting Information [Line Items]
Consolidated segment operating income	8.3	31.2	38.8	95.3
Transportation | Operating segment
Segment Reporting Information [Line Items]
Consolidated segment operating income	8.6	31.2	39.9	95.3
Depreciation expense	$ 0.9	$ 1.0	$ 3.1	$ 3.3