Fair Value Measurements (Assets And Liabilities Measured At Fair Value On A Recurring Basis) (Details) - USD ($) $ in Millions		12 Months Ended
		Dec. 29, 2017	Dec. 30, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities		$ 205.7	$ 133.3
Business Combination, Contingent Consideration, Asset	[1]	0.0	7.0
Assets, Fair Value Disclosure, Recurring		233.3	163.1
Business Combination, Contingent Consideration, Liability	[2]	14.2	4.5
Liabilities, Fair Value Disclosure, Recurring		41.4	27.2
Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Assets, Fair Value Disclosure, Recurring		27.1	22.6
Liabilities, Fair Value Disclosure, Recurring		27.1	22.6
Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities		205.7	133.3
Assets, Fair Value Disclosure, Recurring		206.2	133.5
Liabilities, Fair Value Disclosure, Recurring		0.1	0.1
Level III [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Asset	[1]		7.0
Assets, Fair Value Disclosure, Recurring			7.0
Business Combination, Contingent Consideration, Liability	[2]	14.2	4.5
Liabilities, Fair Value Disclosure, Recurring		14.2	4.5
Deferred Compensation Plan Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	[3]	27.1	22.6
Deferred Compensation Plan Assets [Member] | Fair Value, Inputs, Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair Value, Assets	[3]	27.1	22.6
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	[4]	0.5	0.2
Derivative Financial Instruments, Assets [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contract, Asset, Fair Value Disclosure	[4]	0.5	0.2
Deferred Compensation Plan Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financial Liabilities Fair Value Disclosure	[3]	27.1	22.6
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	[3]	27.1	22.6
Derivative Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contracts, Liability, Fair Value Disclosure	[4]	0.1	0.1
Derivative Liabilities [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Foreign Currency Contracts, Liability, Fair Value Disclosure	[4]	0.1	0.1
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	9.6	11.7
US Treasury Securities [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	9.6	11.7
Municipal Bonds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	0.0	10.0
Municipal Bonds [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	0.0	10.0
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	96.0	31.7
Corporate Debt Securities [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	96.0	31.7
Bank Time Deposits [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	0.0	2.4
Bank Time Deposits [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	0.0	2.4
Commercial Paper [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	100.1	77.5
Commercial Paper [Member] | Level II [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale Securities, Debt Securities	[5]	100.1	$ 77.5
Other Current and Non Current Liabilities [Member] | Maximum [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Business Combination, Contingent Consideration, Liability		50.3
Other Income [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Other Asset Impairment Charges		$ 7.0

[1] Contingent consideration asset represents an arrangement for buyers to pay the Company for a business that it has divested. The fair value is determined based on the Company's expectations of future receipts.

[2] Contingent consideration liabilities represent arrangements to pay the former owners of certain companies that Trimble acquired. The undiscounted maximum payment under the arrangements is $50.3 million at the end of fiscal 2017.

[3] 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. Deferred compensation plan assets and liabilities are included in Other non-current assets and Other non-current liabilities, respectively, on the Company's Consolidated Balance Sheets.

[4] Derivative assets and liabilities primarily represent forward currency exchange contracts. The Company typically enters into these contracts to minimize the short-term impact of foreign currency exchange rates on certain trade and inter-company receivables and payables. Derivative assets and liabilities are included in Other current assets and Other current liabilities on the Company's Consolidated Balance Sheets.

[5] The Company’s available-for sale securities are valued using readily available pricing sources for comparable instruments, or model-driven valuations using significant inputs derived from or corroborated by observable market data, including yield curves and credit ratings.