Fair Value Measurements (Assets And Liabilities Measured At Fair Value On Recurring Basis) (Detail) - USD ($) $ in Millions		Sep. 27, 2019	Dec. 28, 2018
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Consideration, Liabilities	[1]	$ 9.2	$ 5.6
Fair Value Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Contingent Consideration, Liabilities	[1]	9.2	5.6
Deferred Compensation Plan Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	[2]	33.5	28.5
Deferred Compensation Plan Liabilities [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	[2]	33.5	28.5
Derivative Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contracts, Liability, Fair Value Disclosure	[3]	0.3
Derivative Liabilities [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contracts, Liability, Fair Value Disclosure	[3]	0.3
Deferred Compensation Plan Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	[2]	33.5	28.5
Deferred Compensation Plan Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure	[2]	33.5	28.5
Derivative Financial Instruments, Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	[3]	0.6	0.4
Derivative Financial Instruments, Assets [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	[3]	0.6	0.4
Fair Value, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		34.1	28.9
Financial Liabilities Fair Value Disclosure		43.0	34.1
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		33.5	28.5
Financial Liabilities Fair Value Disclosure		33.5	28.5
Fair Value, Recurring [Member] | Fair Value, Inputs, Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure		0.6	0.4
Financial Liabilities Fair Value Disclosure		0.3
Fair Value, Recurring [Member] | Fair Value Inputs, Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure			0.0
Financial Liabilities Fair Value Disclosure		$ 9.2	$ 5.6

[1] Contingent consideration liabilities represent arrangements to pay the former owners of certain companies that Trimble acquired. The fair values are estimated using scenario-based methods or option pricing methods based upon estimated future revenues, gross margins, or other milestones.

[2] The Company maintains a self-directed, non-qualified deferred compensation plan for certain executives and other highly compensated employees. The plan assets and liabilities are invested in actively traded mutual funds and individual stocks valued using observable quoted prices in active markets.

[3] Derivative assets and liabilities primarily represent forward currency exchange contracts to minimize the short-term impact of foreign currency exchange rates on certain trade and inter-company receivables and payables.