Segment Information (Schedule Of Revenue, Operating Income And Identifiable Assets By Segment) (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 30, 2018	Mar. 31, 2017		Dec. 29, 2017
Segment Reporting Information [Line Items]
Revenue	$ 742.2	$ 610.6	[1],[2],[3]
Consolidated segment operating income	64.2	54.7	[2],[4]
Depreciation expense	8.5	8.9	[5]
Accounts receivable	475.7			$ 427.7	[3],[6]
Inventories	289.1			264.6	[3],[6],[7]
Goodwill	2,726.4			2,287.1	[6]
Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	162.9	125.7	[3],[4]
Depreciation expense	4.9	5.1
Resources and Utilities [Member]
Segment Reporting Information [Line Items]
Revenue	159.2	120.2	[1],[3]
Accounts receivable	99.1			78.5	[3]
Inventories	48.6			46.0	[3]
Goodwill	318.4			314.5
Resources and Utilities [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	51.7	42.6	[3]
Depreciation expense	1.0	0.6
Transportation [Member]
Segment Reporting Information [Line Items]
Revenue	183.8	154.3	[1],[3]
Accounts receivable	104.6			107.6	[3]
Inventories	52.4			46.2	[3]
Goodwill	851.8			850.5
Transportation [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	30.4	23.5	[3]
Depreciation expense	1.1	1.4
Buildings and Infrastructure [Member]
Segment Reporting Information [Line Items]
Revenue	224.7	186.5	[1],[3]
Accounts receivable	148.0			120.1	[3]
Inventories	66.3			62.1	[3]
Goodwill	1,139.7			706.8
Buildings and Infrastructure [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	43.5	31.7	[3]
Depreciation expense	1.4	1.8
Geospatial [Member]
Segment Reporting Information [Line Items]
Revenue	174.5	149.6	[1],[3]
Accounts receivable	124.0			121.5	[3]
Inventories	121.8			110.3	[3]
Goodwill	416.5			$ 415.3
Geospatial [Member] | Operating Segments [Member]
Segment Reporting Information [Line Items]
Consolidated segment operating income	37.3	27.9	[3]
Depreciation expense	$ 1.4	$ 1.3

[1] Adjusted to reflect adoption of the new revenue recognition standard, Revenue from Contracts with Customers. For further information, see Note 2.

[2] See Note 2 for a summary of adjustments

[3] See Note 2 for a summary of adjustments

[4] See Note 2 for a summary of adjustments

[5] See Note 2 for a summary of adjustments

[6] See Note 2 for a summary of adjustments

[7] See Note 2 for a summary of adjustments