Updates to Significant Accounting Policies - Revenue From Contract With Customer (Details) - USD ($) $ / shares in Units, $ in Millions		3 Months Ended			6 Months Ended
		Jun. 29, 2018	Jun. 30, 2017		Jun. 29, 2018	Jun. 30, 2017		Mar. 30, 2018	Dec. 29, 2017		Mar. 31, 2017	[7]	Dec. 30, 2016	[7]
Revenue, Initial Application Period Cumulative Effect Transition [Line Items]
Revenue		$ 785.5	$ 659.9	[1],[2],[3]	$ 1,527.7	$ 1,270.5	[1],[2],[3]
Gross margin		422.7	342.6	[2]	818.9	666.9	[2]
Consolidated operating income		89.5	59.0	[2],[4]	153.7	113.7	[2],[4]
Income tax provision		15.1	16.7	[2]	23.1	30.6	[2]
Net income attributable to Trimble Inc.		$ 64.1	$ 47.3	[2]	$ 122.6	$ 97.1	[2]
Diluted earnings per share		$ 0.25	$ 0.18	[2]	$ 0.49	$ 0.38	[2]
Accounts receivable		$ 446.2			$ 446.2				$ 427.7	[3],[5]
Inventories		282.4			282.4				264.6	[3],[5],[6]
Deferred costs, non-current		35.3			35.3				35.0	[5]
Other current adn non-current assets									182.9
Current and non-current deferred revenue		356.2	$ 307.3	[7]	356.2	$ 307.3	[7]	$ 360.4	276.6		$ 302.5		$ 246.4
Other current liabilities		85.0			85.0				99.2	[5]
Deferred income tax liabilities		40.5			40.5				47.8	[5]
Total stockholders' equity		$ 2,517.6			$ 2,517.6				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			661.9			1,275.8
Gross margin			346.5			673.1
Consolidated operating income			62.6			119.2
Income tax provision			17.7			32.8
Net income attributable to Trimble Inc.			$ 49.9			$ 100.4
Diluted earnings per share			$ 0.19			$ 0.39
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]		$ (2.0)			$ (5.3)
Gross margin	[8]		(3.9)			(6.2)
Consolidated operating income	[8]		(3.6)			(5.5)
Income tax provision	[8]		(1.0)			(2.2)
Net income attributable to Trimble Inc.	[8]		$ (2.6)			$ (3.3)
Diluted earnings per share	[8]		$ (0.01)			$ (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