Business Combinations (Narratives) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Apr. 03, 2015	Apr. 04, 2014
Business Acquisition [Line Items]
Number of Businesses Acquired	4us-gaap_NumberOfBusinessesAcquired
Business Acquisition, Transaction Costs	$ 2.8	$ 1.4
Revenue of Business Acquiree Since Acquisition Date Percentage of Total Revenue	1.00%
Series of Individually Immaterial Business Acquisitions [Member] \| Minimum
Business Acquisition [Line Items]
Cash Payments to Acquire Businesses, ranges	3.0
Series of Individually Immaterial Business Acquisitions [Member] \| Maximum
Business Acquisition [Line Items]
Cash Payments to Acquire Businesses, ranges	17.0
General and Administrative Expense [Member]
Business Acquisition [Line Items]
Business Acquisition, Transaction Costs	$ 2.8	$ 1.4

This element represents the percentage of revenue of the acquiree since the acquisition date included in the consolidated income statement for the reporting period.

No definition available.

+ Details

Name:	trmb_BusinessCombinationProFormaInformationRevenueOfAcquireeSinceAcquisitionDateActualPercentage
Namespace Prefix:	trmb_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 805

-SubTopic 10

-Section 25

-Paragraph 23

-URI http://asc.fasb.org/extlink&oid=34752592&loc=d3e1043-128460

+ Details

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The number of businesses acquired by the entity during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_NumberOfBusinessesAcquired
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The cash outflow associated with the acquisition of business during the period. The cash portion only of the acquisition price.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Glossary Investing Activities

-URI http://asc.fasb.org/extlink&oid=6516133

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 13

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3213-108585

+ Details

Name:	us-gaap_PaymentsToAcquireBusinessesGross
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=us-gaap_SeriesOfIndividuallyImmaterialBusinessAcquisitionsMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_IncomeStatementLocationAxis=us-gaap_GeneralAndAdministrativeExpenseMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: