Pensions Plan Assets excluding FV disclosures (Details) (USD $) In Millions	12 Months Ended
Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
Pension and Other Postretirement Benefit Plans Details [Abstract]
Pension and Other Postretirement Benefit Contributions	$ 24.4	$ 41.1	$ 20.7
Estimated Contributions In Next Fiscal Year	Contributions are estimated at between $20 and $30 million for 2011.
Domestic Pension Benefits
Change in Fair Value of Plan Assets
Fair Value of Plan Assets at Beginning of Year	347.1	292.0
Business combination	0	0
Actual return on plan assets	34.7	63.3
Employer contribution	0.4	11.3
Plan participants' contributions	0	0
Benefits paid	(19.7)	(19.5)
Currency translation and other	0	0
Fair Value of Plan Assets at End of Year	362.5	347.1
Non-U.S. Pension Benefits
Change in Fair Value of Plan Assets
Fair Value of Plan Assets at Beginning of Year	475.0	368.9
Business combination	1.3	9.8
Actual return on plan assets	45.5	60.4
Employer contribution	21.5	27.3
Plan participants' contributions	3.3	3.1
Benefits paid	(24.1)	(21.5)
Currency translation and other	(12.0)	27.0
Fair Value of Plan Assets at End of Year	510.5	475.0
SERP Benefits [Member]
Change in Fair Value of Plan Assets
Fair Value of Plan Assets at Beginning of Year	0	0
Employer contribution	0.4	0.5
Plan participants' contributions	0	0
Benefits paid	(0.4)	(0.5)
Fair Value of Plan Assets at End of Year	0	0
Other Postretirement Benefit Plans Defined Benefit [Member]
Change in Fair Value of Plan Assets
Fair Value of Plan Assets at Beginning of Year	0	0
Employer contribution	2.1	2.0
Plan participants' contributions	1.4	1.4
Benefits paid	(3.5)	(3.4)
Fair Value of Plan Assets at End of Year	$ 0	$ 0

Name:	tmo_PensionAndOtherPostretirementBenefitPlansDetailsAbstract
Namespace Prefix:	tmo
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

The difference between fair value of plan assets at the end of the period and the fair value at the beginning of the period, adjusted for contributions and payments of benefits during the period, and after adjusting for taxes and other expenses, as applicable.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph d(iv)(b)(i)

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b

+ Details

Name:	us-gaap_DefinedBenefitPlanActualReturnOnPlanAssets
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of payments made for which participants are entitled under a pension plan, including pension benefits, death benefits, and benefits due on termination of employment. Also includes payments made under a postretirement benefit plan, including prescription drug benefits, health care benefits, life insurance benefits, and legal, educational and advisory services.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph a, b

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 106
-Paragraph 518

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 264

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name FASB Staff Position (FSP)
-Number FAS106-2
-Paragraph 22

+ Details

Name:	us-gaap_DefinedBenefitPlanBenefitsPaid
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of increase in the plan assets attributed to a business combination.

+ References

+ Details

Name:	us-gaap_DefinedBenefitPlanBusinessCombinationsAndAcquisitionsPlanAssets
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ Details

Name:	us-gaap_DefinedBenefitPlanChangeInFairValueOfPlanAssetsRollForward
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of contributions made by the employer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b

+ Details

Name:	us-gaap_DefinedBenefitPlanContributionsByEmployer
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of contributions made by plan participants. Under a contributory plan active employees or retirees contribute part of the cost. In some contributory plans, those wishing to be covered must contribute; in others, the contributions result in increased benefits.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b

+ Details

Name:	us-gaap_DefinedBenefitPlanContributionsByPlanParticipants
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Descriptive information regarding the employer's best estimate, as soon as it can be reasonably determined, of contributions expected to be paid to the plan during the next fiscal year beginning after the date of the latest statement of financial position. Estimated contributions may be presented in the aggregate combining (1) contributions required by funding regulations or laws, (2) discretionary contributions, and (3) noncash contributions. Description may include a range of expected contributions, required minimum contribution, whether the expected contribution is discretionary, and further explanation.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph g

+ Details

Name:	us-gaap_DefinedBenefitPlanEstimatedFutureEmployerContributionsInNextFiscalYearDescription
Namespace Prefix:	us-gaap
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Assets, usually stocks, bonds, and other investments, that have been segregated and restricted (usually in a trust) to provide benefits, at their fair value as of the measurement date. Plan assets include amounts contributed by the employer (and by employees for a contributory plan) and amounts earned from investing the contributions, less benefits paid. If a plan has liabilities other than for benefits, those nonbenefit obligations may be considered as reductions of plan assets.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph d(iv)(b)(i)

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 87
-Paragraph 49

+ Details

Name:	us-gaap_DefinedBenefitPlanFairValueOfPlanAssets
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The amount of increase or decrease in plan assets attributed to foreign currency changes. The effects of foreign currency exchange rate changes that are to be disclosed are those applicable to plans of a foreign operation whose functional currency is not the reporting currency.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 132R
-Paragraph 5
-Subparagraph b

+ Details

Name:	us-gaap_DefinedBenefitPlanForeignCurrencyExchangeRateChangesPlanAssets
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The amount of cash or cash equivalents contributed during the reporting period by the entity to fund its pension plans and its non-pension postretirement benefit plans.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Statement of Financial Accounting Standard (FAS)
-Number 95
-Paragraph 28

+ Details

Name:	us-gaap_PensionAndOtherPostretirementBenefitContributions
Namespace Prefix:	us-gaap
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration