Updates to Significant Accounting Policies - Revenue From Contract With Customer (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended
		Mar. 30, 2018	Mar. 31, 2017		Dec. 29, 2017		Dec. 30, 2016	[7]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		$ 742.2	$ 610.6	[1],[2],[3]
Gross margin		396.2	324.3	[2]
Consolidated operating income		64.2	54.7	[2],[4]
Income tax provision		8.0	13.9	[2]
Net income attributable to Trimble Inc.		$ 58.5	$ 49.8	[2]
Diluted earnings per share		$ 0.23	$ 0.19	[2]
Accounts receivable		$ 475.7			$ 427.7	[3],[5]
Inventories		289.1			264.6	[3],[5],[6]
Deferred costs, non-current		35.6			35.0	[5]
Other current adn non-current assets					182.9
Current and non-current deferred revenue		360.4	$ 302.5	[7]	276.6		$ 246.4
Other current liabilities		110.0			99.2	[5]
Deferred income tax liabilities		49.8			47.8	[5]
Total stockholders' equity		$ 2,499.9			2,414.5	[5]
Calculated under Revenue Guidance in Effect before Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue			613.9
Gross margin			326.6
Consolidated operating income			56.6
Income tax provision			15.1
Net income attributable to Trimble Inc.			$ 50.5
Diluted earnings per share			$ 0.20
Accounts receivable					414.8
Inventories					271.8
Deferred costs, non-current					0.0
Other current adn non-current assets					205.5
Current and non-current deferred revenue					313.4
Other current liabilities					101.0
Deferred income tax liabilities					40.4
Total stockholders' equity					2,366.0
Difference between Revenue Guidance in Effect before and after Topic 606 [Member] | Accounting Standards Update 2014-09 [Member]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue	[8]		$ (3.3)
Gross margin	[8]		(2.3)
Consolidated operating income	[8]		(1.9)
Income tax provision	[8]		(1.2)
Net income attributable to Trimble Inc.	[8]		$ (0.7)
Diluted earnings per share	[8]		$ (0.01)
Accounts receivable	[8]				12.9
Inventories	[8]				(7.2)
Deferred costs, non-current	[8]				35.0
Other current adn non-current assets	[8]				(22.6)
Current and non-current deferred revenue	[8]				(36.8)
Other current liabilities	[8]				(1.8)
Deferred income tax liabilities	[8]				7.4
Total stockholders' equity	[8]				$ 48.5

[1] Adjusted to reflect adoption of the new revenue recognition standard, Revenue from Contracts with Customers. For further information, see Note 2.

[2] See Note 2 for a summary of adjustments

[3] See Note 2 for a summary of adjustments

[4] See Note 2 for a summary of adjustments

[5] See Note 2 for a summary of adjustments

[6] See Note 2 for a summary of adjustments

[7] See Note 2 for a summary of adjustments

[8] Adjusted to reflect the adoption of Revenue from Contracts with Customers