Selected Quarterly Financial Data (Schedule Of Selected Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 29, 2017	Sep. 29, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 30, 2016	Sep. 30, 2016	Jul. 01, 2016	Apr. 01, 2016	Dec. 28, 2018	Dec. 29, 2017	[1]	Dec. 30, 2016	[1]
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 785.5	$ 795.2	$ 785.5	$ 742.2	$ 699.8	$ 676.2	$ 659.9	$ 610.6	$ 3,108.4	$ 2,646.5		$ 2,362.1
Gross Profit	435.2	426.9	422.7	396.2	359.5	351.2	342.6	324.3	1,681.0	1,377.6		1,234.5
Net income attributable to Trimble Inc.	$ 86.5	$ 73.7	$ 64.1	$ 58.5	$ (35.9)	$ 57.2	$ 47.3	$ 49.8	$ 282.8	$ 118.4		$ 132.4
Basic net income per share	$ 0.34	$ 0.29	$ 0.26	$ 0.24	$ (0.14)	$ 0.23	$ 0.19	$ 0.20	$ 1.13	$ 0.47		$ 0.53
Diluted net income per share	$ 0.34	$ 0.29	$ 0.25	$ 0.23	$ (0.14)	$ 0.22	$ 0.18	$ 0.19	$ 1.12	$ 0.46		$ 0.52

[1] See Note 2 for a summary of adjustments