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. 29, 2017		Dec. 30, 2016		Jan. 01, 2016
Quarterly Financial Information Disclosure [Abstract]
Revenues	$ 708.4	$ 670.0	$ 661.9	$ 613.9	$ 585.5	$ 584.1	$ 609.6	$ 583.0	$ 2,654.2	[1]	$ 2,362.2	[1]	$ 2,290.4	[1]
Gross margin	370.0	349.5	346.5	326.6	312.8	309.0	315.6	300.6	1,392.6		1,238.0		1,202.2
Net income attributable to Trimble Inc.	$ (35.0)	$ 55.7	$ 49.9	$ 50.5	$ 37.7	$ 39.2	$ 35.7	$ 19.8	$ 121.1		$ 132.4		$ 121.1
Basic net income per share	$ (0.14)	$ 0.22	$ 0.20	$ 0.20	$ 0.15	$ 0.16	$ 0.14	$ 0.08	$ 0.48		$ 0.53		$ 0.47
Diluted net income per share	$ (0.14)	$ 0.22	$ 0.19	$ 0.20	$ 0.15	$ 0.15	$ 0.14	$ 0.08	$ 0.47		$ 0.52		$ 0.47

[1] Revenue is attributed to countries based on the location of the customer.