Selected Quarterly Financial Data (Schedule Of Selected Quarterly Financial Data) (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Jan. 03, 2020	Sep. 27, 2019	Jun. 28, 2019	Mar. 29, 2019	Dec. 28, 2018	Sep. 28, 2018	Jun. 29, 2018	Mar. 30, 2018	Jan. 03, 2020	Dec. 28, 2018	Dec. 29, 2017
Quarterly Financial Information Disclosure [Abstract]
Revenue	$ 824.0	$ 783.9	$ 854.8	$ 801.6	$ 785.5	$ 795.2	$ 785.5	$ 742.2	$ 3,264.3	$ 3,108.4	$ 2,646.5
Gross Profit	460.0	422.0	460.6	438.3	435.2	426.9	422.7	396.2	1,780.9	1,681.0	1,377.6
Net income attributable to Trimble Inc.	$ 279.3	$ 78.1	$ 94.6	$ 62.3	$ 86.5	$ 73.7	$ 64.1	$ 58.5	$ 514.3	$ 282.8	$ 118.4
Basic net income per share	$ 1.12	$ 0.31	$ 0.38	$ 0.25	$ 0.34	$ 0.29	$ 0.26	$ 0.24	$ 2.05	$ 1.13	$ 0.47
Diluted net income per share	$ 1.11	$ 0.31	$ 0.37	$ 0.25	$ 0.34	$ 0.29	$ 0.25	$ 0.23	$ 2.03	$ 1.12	$ 0.46