Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 29, 2017	Sep. 30, 2016	Sep. 29, 2017	Sep. 30, 2016	Dec. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 670.0	$ 584.1	$ 1,945.8	$ 1,776.7
Consolidated segment operating income	64.0	55.3	183.2	125.7
Depreciation expense			26.4	27.9
Accounts receivable	407.2		407.2		$ 354.8
Inventories	254.7		254.7		218.8
Goodwill	2,289.3		2,289.3		2,077.6
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	214.5	189.3	625.3	565.8
Accounts receivable	117.1		117.1		104.7
Inventories	57.8		57.8		51.3
Goodwill	705.9		705.9		663.7
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	169.7	159.9	484.8	476.0
Accounts receivable	122.4		122.4		108.3
Inventories	106.7		106.7		100.4
Goodwill	415.7		415.7		405.1
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	114.4	87.5	345.3	300.3
Accounts receivable	69.7		69.7		65.5
Inventories	41.5		41.5		31.0
Goodwill	317.0		317.0		217.7
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	171.4	147.4	490.4	434.6
Accounts receivable	98.0		98.0		76.3
Inventories	48.7		48.7		36.1
Goodwill	850.7		850.7		$ 791.1
Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	146.6	127.9	415.8	352.8
Depreciation expense	5.1	5.1	15.2	15.9
Operating Segments [Member] \| Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	52.2	40.9	135.3	102.2
Depreciation expense	1.4	1.7	4.7	5.4
Operating Segments [Member] \| Geospatial [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	36.7	35.3	94.8	89.9
Depreciation expense	1.5	1.5	4.3	5.0
Operating Segments [Member] \| Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	26.5	25.2	103.5	90.0
Depreciation expense	0.9	0.5	2.1	1.5
Operating Segments [Member] \| Transportation [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	31.2	26.5	82.2	70.7
Depreciation expense	$ 1.3	$ 1.4	$ 4.1	$ 4.0

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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