Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Detail) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2017	Jul. 01, 2016	Jun. 30, 2017	Jul. 01, 2016	Dec. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 661.9	$ 609.6	$ 1,275.8	$ 1,192.6
Consolidated segment operating income	62.6	40.5	119.2	70.4
Depreciation expense			17.7	18.8
Accounts receivable	395.3		395.3		$ 354.8
Inventories	223.3		223.3		218.8
Goodwill	2,183.7		2,183.7		2,077.6
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	222.7	202.8	410.8	376.5
Accounts receivable	127.4		127.4		104.7
Inventories	50.3		50.3		51.3
Goodwill	690.8		690.8		663.7
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	165.3	163.9	315.1	316.1
Accounts receivable	118.7		118.7		108.3
Inventories	100.9		100.9		100.4
Goodwill	409.0		409.0		405.1
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	111.0	99.0	230.9	212.8
Accounts receivable	64.7		64.7		65.5
Inventories	30.7		30.7		31.0
Goodwill	254.7		254.7		217.7
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	162.9	143.9	319.0	287.2
Accounts receivable	84.5		84.5		76.3
Inventories	41.4		41.4		36.1
Goodwill	829.2		829.2		$ 791.1
Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	141.6	117.7	269.2	224.9
Depreciation expense	5.0	5.6	10.1	10.8
Operating Segments [Member] \| Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	50.4	38.9	83.1	61.3
Depreciation expense	1.5	1.9	3.3	3.7
Operating Segments [Member] \| Geospatial [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	30.2	28.5	58.1	54.6
Depreciation expense	1.5	1.9	2.8	3.5
Operating Segments [Member] \| Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	34.8	29.9	77.0	64.8
Depreciation expense	0.6	0.5	1.2	1.0
Operating Segments [Member] \| Transportation [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	26.2	20.4	51.0	44.2
Depreciation expense	$ 1.4	$ 1.3	$ 2.8	$ 2.6

Amount due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer), for goods or services (including trade receivables) that have been delivered or sold in the normal course of business, reduced to the estimated net realizable fair value by an allowance established by the entity of the amount it deems uncertain of collection.

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