Income 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		9 Months Ended
	Oct. 02, 2015	Oct. 03, 2014	Oct. 02, 2015	Oct. 03, 2014
Earnings Per Share Reconciliation [Abstract]
Net income attributable to Trimble Navigation Ltd.	$ 37.1	$ 11.8	$ 97.1	$ 158.3
Weighted average number of common shares used in basic income per share	254.8	260.3	257.5	260.4
Effect of dilutive securities	2.4	4.1	2.8	4.7
Weighted average number of common shares and dilutive potential common shares used in diluted income per share	257.2	264.4	260.3	265.1
Basic income per share	$ 0.15	$ 0.05	$ 0.38	$ 0.61
Diluted income per share	$ 0.14	$ 0.04	$ 0.37	$ 0.60