Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2017	Apr. 01, 2016	Dec. 30, 2016
Segment Reporting Information [Line Items]
Revenue	$ 613.9	$ 583.0
Consolidated segment operating income	56.6	29.9
Depreciation expense	8.9	9.1
Accounts receivable	394.7		$ 354.8
Inventories	221.1		218.8
Goodwill	2,128.6		2,077.6
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	188.1	173.7
Accounts receivable	117.7		104.7
Inventories	49.9		51.3
Goodwill	674.9		663.7
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	149.8	152.2
Accounts receivable	112.4		108.3
Inventories	104.4		100.4
Goodwill	403.2		405.1
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	119.9	113.8
Accounts receivable	83.9		65.5
Inventories	29.0		31.0
Goodwill	233.5		217.7
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	156.1	143.3
Accounts receivable	80.7		76.3
Inventories	37.8		36.1
Goodwill	817.0		$ 791.1
Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	127.6	107.2
Depreciation expense	5.1	5.2
Operating Segments [Member] | Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	32.7	22.4
Depreciation expense	1.8	1.8
Operating Segments [Member] | Geospatial [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	27.9	26.1
Depreciation expense	1.3	1.6
Operating Segments [Member] | Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	42.2	34.9
Depreciation expense	0.6	0.5
Operating Segments [Member] | Transportation [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	24.8	23.8
Depreciation expense	$ 1.4	$ 1.3