Earnings Per Share (Schedule Of Computation Of Earnings Per Share And Effect On Weighted-Average Number Of Shares) (Details) - USD ($) $ / shares in Units, shares in Millions, $ 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
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
Weighted average number of common shares used in basic earnings per share									252.1	250.5	255.8
Effect of dilutive securities									4.6	3.4	2.7
Weighted average number of common shares and dilutive potential common shares used in diluted earnings per share									256.7	253.9	258.5
Basic earnings 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 earnings per share	$ (0.14)	$ 0.22	$ 0.19	$ 0.20	$ 0.15	$ 0.15	$ 0.14	$ 0.08	$ 0.47	$ 0.52	$ 0.47