Earnings Per Share (Schedule Of Computation Of Earnings Per Share And Effect On Weighted-Average Number Of Shares) (Detail) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended
	Mar. 29, 2019	Mar. 30, 2018
Earnings Per Share Reconciliation [Abstract]
Net income attributable to Trimble Inc.	$ 62.3	$ 58.5
Weighted average number of common shares used in basic earnings per share	251.5	248.8
Effect of dilutive securities	2.5	4.4
Weighted average number of common shares and dilutive potential common shares used in diluted earnings per share	254.0	253.2
Basic earnings per share	$ 0.25	$ 0.24
Diluted earnings per share	$ 0.25	$ 0.23