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. 30, 2018	Mar. 31, 2017
Earnings Per Share Reconciliation [Abstract]
Net income attributable to Trimble Inc.	$ 58.5	$ 49.8	[1]
Weighted average number of common shares used in basic earnings per share	248.8	252.0	[1]
Effect of dilutive securities	4.4	3.9
Weighted average number of common shares and dilutive potential common shares used in diluted earnings per share	253.2	255.9	[1]
Basic earnings per share	$ 0.24	$ 0.20	[1]
Diluted earnings per share	$ 0.23	$ 0.19	[1]

[1] See Note 2 for a summary of adjustments