Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Trading Arrangement: Trading Arrangement [Axis] Consumables Product, Consumables [Member] Consumable, single-use products Maximum Maximum [Member] Fair value – assets Offsetting Derivative Assets [Abstract] Statistical Measurement [Domain] Statistical Measurement [Domain] Short-term Debt, Type [Axis] Short-Term Debt, Type [Axis] Title of 12(b) Security Title of 12(b) Security Subsequent Event Subsequent Event [Member] 5.404% 20-Year Senior Notes, Due 8/10/2043 Senior Notes 5.404% Due 2043 [Member] Senior Notes 5.404% Due 2043 Document Fiscal Year Focus Document Fiscal Year Focus Gross amounts subject to offset in master netting arrangements not offset in the consolidated balance sheets Derivative Liability, Subject to Master Netting Arrangement, Asset Offset 5.30% 30-Year Senior Notes, Due 2/1/2044 Senior Notes 5.30% Due 2044 [Member] 5.30% 30-Year Senior Notes, Due 2/1/2044 [Member] Remaining performance obligation, expected timing Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Period Bank time deposits Cash Equivalent, Time Deposit, Carrying Value 1.45% 10-Year Senior Notes, Due 3/16/2027 (euro-denominated) 1.45% Senior Notes Due 2027 [Member] 1.45% 10-Year Senior Notes, Due 3/16/2027 (euro-denominated) Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] Adjustment to Compensation, Amount Adjustment to Compensation Amount Schedule of Reconciliation of Unrecognized Tax Benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Segment Reporting [Abstract] Segment Reporting [Abstract] Common stock, $1 par value, 1,200,000,000 shares authorized; 445,673,899 and 445,160,301 shares issued Common Stock, Value, Issued Accrued payroll and employee benefits Employee-related Liabilities, Current Settlements Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis] State and local income taxes, net of federal income tax effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Restatement Determination Date Restatement Determination Date Other Other Debt [Member] Other Debt Proceeds from sales and maturities of investments Proceeds from Sale, Maturity and Collection of Investments Tax Jurisdiction of Domicile [Extensible Enumeration] Tax Jurisdiction of Domicile [Extensible Enumeration] Changes in valuation allowances Benefit in jurisdictions for deferred tax assets Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount 5.00% 5-Year Senior Notes, Due 1/31/2029 Senior Notes 5.00% Due 2029 [Member] Senior Notes 5.00% Due 2029 Derivative Instrument [Axis] Derivative Instrument [Axis] Effect of changes in tax laws or rates enacted in the current period Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Schedule of Effective Income Tax Rate Reconciliation Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] 1.50% 12-Year Senior Notes, Due 9/6/2035 (Japanese yen-denominated) Senior Notes 1.50% Due 2035 [Member] Senior Notes 1.50% Due 2035 ImmunoDiagnostics ImmunoDiagnostics [Member] ImmunoDiagnostics Amendment Flag Amendment Flag Current liabilities: Liabilities, Current [Abstract] Schedule of the Aggregate Notional Value of Outstanding Derivative Contracts Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Acquisitions (including assumed balances) Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Issuances Seller note Disposal Group, Including Discontinued Operation, Consideration, Seller Note Disposal Group, Including Discontinued Operation, Consideration, Seller Note Disposal Group Classification [Axis] Disposal Group Classification [Axis] Percent Effective Income Tax Rate Reconciliation, Percent [Abstract] Held for sale Disposal Group, Held-for-Sale, Not Discontinued Operations [Member] 4.215% 5-Year Senior Notes, Due 2/12/2031 Senior Notes 4.215% Due 2031 [Member] Senior Notes 4.215% Due 2031 Foreign tax effects Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] 2.00% 30-Year Senior Notes, Due 10/18/2051 (euro-denominated) Senior Notes 2.00% Due 2051 [Member] Senior Notes 2.00% Due 2051 Entity Address, State or Province Entity Address, State or Province 1.50% 20-Year Senior Notes, Due 10/1/2039 (euro-denominated) Senior Notes 1.500% Due 2039 [Member] Senior Notes 1.500% Due 2039 [Member] PEO Total Compensation Amount PEO Total Compensation Amount 1.47% 25-Year Senior Notes, Due 1/6/2050 (Swiss franc-denominated) Senior Notes 1.47% Due 2050 [Member] Senior Notes 1.47% Due 2050 Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Assets Assets, Fair Value Disclosure [Abstract] Purchases of property, plant and equipment Segment Reporting, Long-Lived Asset, Expenditure for Addition Acquisition-related intangible assets, net Intangible Asset, Excluding Goodwill, after Accumulated Amortization Notional amount Derivative, Notional Amount Additions for tax positions of prior years Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Contributions from (distributions to) noncontrolling interests Temporary Equity, Decrease from Distributions to Noncontrolling Interest Holders Temporary Equity, Decrease from Distributions to Noncontrolling Interest Holders Cumulative translation adjustment: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax [Abstract] Basic (in shares) Basic weighted average shares (in shares) Weighted Average Number of Shares Outstanding, Basic Contract assets, net Current contract assets, net Contract with Customer, Asset, after Allowance for Credit Loss, Current Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Healthcare market channel Healthcare Market Channel [Member] Healthcare Market Channel Fair Value, by Balance Sheet Grouping [Table] Fair Value, by Balance Sheet Grouping [Table] 1.875% 30-Year Senior Notes, Due 10/1/2049 (euro-denominated) Senior Notes 1.875% Due 2049 [Member] Senior Notes 1.875% Due 2049 [Member] Number of reportable segments Number of Reportable Segments Total current liabilities Liabilities, Current Subsegments Consolidation Items [Axis] Subsegments Consolidation Items [Axis] Work in process Inventory, Work in Process, Net of Reserves Customer relationships Customer Relationships [Member] Instruments Product, Instruments [Member] Instruments (longer-lived products) Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Comprehensive income/(loss) Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Entity Address, City or Town Entity Address, City or Town 2.0375% 12-Year Senior Notes, Due 3/7/2036 (Swiss franc-denominated) Senior Notes 2.0375% Due 2036 [Member] Senior Notes 2.0375% Due 2036 Schedule of Supplemental Cash Flow Information Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Effect of cross-border tax laws Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Percent 1.279% 7-Year Senior Notes, Due 10/19/2029 (Japanese yen-denominated) Senior Notes 1.279% Due 2029 [Member] Senior Notes 1.279% Due 2029 Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Product revenues Product [Member] Class of Stock [Axis] Class of Stock [Axis] Specialty Diagnostics Specialty Diagnostics [Member] Specialty Diagnostics Segment Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Marc N. Casper [Member] Marc N. Casper Significant Other Observable Inputs (Level 2) Fair Value, Inputs, Level 2 [Member] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Countries with taxable presence Number Of Countries With Taxable Presence Number Of Countries With Taxable Presence Net other comprehensive income/(loss) Other Comprehensive Income (Loss), Net of Tax Borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] 1.8401% 8-Year Senior Notes, Due 3/8/2032 (Swiss franc-denominated) Senior Notes 1.8401% Due 2032 [Member] Senior Notes 1.8401% Due 2032 Clinical diagnostics Clinical Diagnostics [Member] Clinical Diagnostics Tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent Subsequent Event Type [Axis] Subsequent Event Type [Axis] 2.375% Notes due 2032 Senior Notes 2.375% Due 2032 [Member] Senior Notes 2.375% Due 2032 Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Euro Commercial Paper Program Euro Commercial Paper Program [Member] Borrowings under the company's euro commercial paper program Recent Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Acquired but unpaid property, plant and equipment Capital Expenditures Incurred but Not yet Paid Schedule of Business Segment Information Segment Reporting [Table Text Block] Noncontrolling Interests Noncontrolling Interest [Member] BioProduction BioProduction [Member] BioProduction 0.790% 3-Year Senior Notes, Due 1/6/2028 (Swiss franc-denominated) Senior Notes 0.790% Due 2028 [Member] Senior Notes 0.790% Due 2028 Use of Estimates Use of Estimates, Policy [Policy Text Block] Chemical analysis Chemical Analysis [Member] Chemical Analysis Other comprehensive income/(loss) Other Comprehensive Income (Loss), Net Of Tax, Excluding Redeemable Noncontrolling Interest Other Comprehensive Income (Loss), Net Of Tax, Excluding Redeemable Noncontrolling Interest 4.894% 12-Year Senior Notes, Due 10/7/2037 Senior Notes 4.894% Due 2037 [Member] Senior Notes 4.894% Due 2037 Schedule of Fair Value of Investments, Liabilities Measured on Recurring Basis Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Total borrowings at carrying value Carrying value Long-Term Debt Document Period End Date Document Period End Date 1.054% 5-Year Senior Notes, Due 10/20/2027 (Japanese yen-denominated) Senior Notes 1.054% Due 2027 [Member] Senior Notes 1.054% Due 2027 Pension and other postretirement benefit liability adjustments arising during the period (net of tax (provision) benefit of $0, $3, $(1), and $4) Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, after Tax Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Current liabilities Disposal Group, Including Discontinued Operation, Liabilities, Current Unrecognized tax benefits Balance at beginning of year Balance at end of period Unrecognized Tax Benefits Comprehensive Income/(Loss) and Shareholders' Equity Equity [Text Block] 5.086% 10-Year Senior Notes, Due 8/10/2033 Senior Notes 5.086% Due 2033 [Member] Senior Notes 5.086% Due 2033 Costs and operating expenses: Costs and Expenses [Abstract] Security Exchange Name Security Exchange Name Term Debt Instrument, Term Treasury stock at cost, 75,926,613 and 68,938,831 shares Treasury Stock, Common, Value Effective interest rate Debt Instrument, Interest Rate, Effective Percentage 0.50% 8.5-Year Senior Notes, Due 3/1/2028 (euro-denominated) Senior Notes 0.500% Due 2028 [Member] Senior Notes 0.500% Due 2028 [Member] 2.875% 20-Year Senior Notes, Due 7/24/2037 (euro-denominated) Senior Notes 2.875% Due 2037 [Member] 2.875% 20-Year Senior Notes, Due 7/24/2037 (euro-denominated) [Member] 5.546% 20-Year Senior Notes, Due 2/12/2046 Senior Notes 5.546% Due 2046 [Member] Senior Notes 5.546% Due 2046 Supplemental Cash Flow Information Cash Flow, Supplemental Disclosures [Text Block] Total liabilities Liabilities, Fair Value Disclosure Accumulated other comprehensive income/(loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Entity Shell Company Entity Shell Company Consolidation Items [Domain] Consolidation Items [Domain] Changes in fair value included in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Other adjustments Effective Income Tax Rate Reconciliation, Other Adjustments, Amount 4.10% 30-Year Senior Notes, Due 8/15/2047 Senior Notes 4.10% Due 2047 [Member] 4.10% 30-Year Senior Notes, Due 8/15/2047 [Member] Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Foreign currency-denominated debt and other payables Foreign currency-denominated debt [Member] Foreign currency-denominated debt [Member] 1.90% 12-Year Senior Notes, Due 3/3/2038 (Swiss franc-denominated) Senior Notes 1.90% Due 2038 [Member] Senior Notes 1.90% Due 2038 Name Outstanding Recovery, Individual Name Earnings per share attributable to Thermo Fisher Scientific Inc. Earnings Per Share [Abstract] Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Document Fiscal Period Focus Document Fiscal Period Focus Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Net other assets/(liabilities) Business Combination, Recognized Asset Acquired, Other Asset Business Combination, Recognized Asset Acquired, Other Asset Trading Symbol Trading Symbol Geographical [Domain] Geographical [Domain] Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Reconciliation of Unrecognized Tax Benefits [Roll Forward] Unrecognized Tax Benefits [Roll Forward] Supplemental Income Statement Elements [Abstract] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] 1.75% 7-Year Senior Notes, Due 4/15/2027 (euro-denominated) Senior Notes 1.75% Due 2027 [Member] Senior Notes 1.75% Due 2027 Company Selected Measure Name Company Selected Measure Name Schedule of Cash, Cash Equivalents and Restricted Cash Restrictions on Cash and Cash Equivalents [Table Text Block] Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Non-cash investing and financing activities Noncash Investing and Financing Items [Abstract] 1.625% 20-Year Senior Notes, Due 10/18/2041 (euro-denominated) Senior Notes 1.625% Due 2041 [Member] Senior Notes 1.625% Due 2041 Pension and other postretirement benefit liability adjustment Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Total borrowings at par value Long-Term Debt, Gross Cross-currency interest rate swaps designated as net investment hedge - Swiss franc Switzerland, Francs Changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Percent Asset Class [Domain] Asset Class [Domain] Credit Facility [Domain] Credit Facility [Domain] Operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Compensation Amount Outstanding Recovery Compensation Amount Individual: Individual [Axis] Diluted (in shares) Diluted weighted average shares (in shares) Weighted Average Number of Shares Outstanding, Diluted Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Backlog Order or Production Backlog [Member] Cross-currency interest rate swaps Cross Currency Interest Rate Contract [Member] Proceeds from cross-currency interest rate swap interest settlements Proceeds From (Payments For) Cross-Currency Interest Rate Swap Interest Settlements The cash inflow (outflow) provided by (paid for) cross-currency interest rate swap interest rate settlements, which are classified as investing activities, for hedging instruments designated as net investment hedges. Entity Emerging Growth Company Entity Emerging Growth Company Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Disposal Group Name [Domain] Disposal Group Name [Domain] Line of Credit Facility [Table] Line of Credit Facility [Table] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Commercial Paper Commercial Paper [Member] Derivatives Derivative Instruments and Hedging Activities Disclosure [Text Block] Declared but unpaid dividends Dividends Payable Pharma services Pharma Services [Member] Pharma Services Disposal Groups, Including Discontinued Operations Disposal Groups, Including Discontinued Operations [Table Text Block] Fair value – liabilities Gross amounts recognized in the consolidated balance sheets Derivative Liability, Subject to Master Netting Arrangement, before Offset Schedule of Fair Value of Investments, Assets Measured on Recurring Basis Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Proceeds from issuance of commercial paper Proceeds from Issuance of Commercial Paper Impairment of long-lived assets Long-Lived Asset, Held and Used, Impairment Loss 2.11% 20-Year Senior Notes, Due 3/3/2046 (Swiss franc-denominated) Senior Notes 2.11% Due 2046 [Member] Senior Notes 2.11% Due 2046 Changes in assets and liabilities, excluding the effects of acquisitions Increase (Decrease) in Other Operating Assets and Liabilities, Net Tax provision (benefit) on cumulative translation adjustment OCI, Foreign Currency Transaction and Translation Gain (Loss), Arising During Period, Tax Award Timing Predetermined Award Timing Predetermined [Flag] Treasury Stock Treasury Stock, Common [Member] Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Stock-based compensation APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Total derivatives, net Derivative Liability, Subject to Master Netting Arrangement, after Offset Quoted Prices in Active Markets (Level 1) Fair Value, Inputs, Level 1 [Member] Tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Amount Effective tax rate Effective Income Tax Rate Reconciliation, Percent Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] 5.00% 3-Year Senior Notes, Due 12/5/2026 Senior Notes 5.00% Due 2026 [Member] Senior Notes 5.00% Due 2026 Plus effect of: stock options and restricted stock units (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements All Executive Categories All Executive Categories [Member] Currency translation Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Foreign Currency Translation Adjustments Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Foreign Currency Translation Adjustments Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Other comprehensive income/(loss): Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent [Abstract] Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Redeemable noncontrolling interest Beginning balance Ending balance Redeemable Noncontrolling Interest, Equity, Carrying Amount Depreciation of property, plant and equipment Depreciation Excise tax from stock repurchases Stock Repurchased During Period, Value, Excise Tax Payable Stock Repurchased During Period, Value, Excise Tax Payable Analytical Instruments Analytical Instruments [Member] Analytical Instruments Segment 1.49% 10-Year Senior Notes, Due 10/20/2032 (Japanese yen-denominated) Senior Notes 1.49% Due 2032 [Member] Senior Notes 1.49% Due 2032 Schedule of Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Total assets acquired Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Intra-entity transfers Effective Income Tax Rate Reconciliation, Disposition of Asset, Amount Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Business Segment Information Segment Reporting [Text Block] Borrowings outstanding Long-Term Line of Credit Minimum Minimum [Member] Dividends paid Payments of Ordinary Dividends, Common Stock 0.50% 8.5-Year Senior Notes, Due 3/1/2028 (euro-denominated) Senior Notes 0.50% Due 2028 [Member] Senior Notes 0.50% Due 2028 Expiration Date Trading Arrangement Expiration Date Chromatography and mass spectrometry Chromatography And Mass Spectrometry [Member] Chromatography And Mass Spectrometry Investments Investments, Fair Value Disclosure Hedging Relationship [Axis] Hedging Relationship [Axis] Schedule of Disaggregated Revenues Disaggregation of Revenue [Table Text Block] Income Statement Location [Axis] Location, Statement of Income, Balance [Axis] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Cash equivalents Cash and Cash Equivalents, Fair Value Disclosure Total equity Beginning balance Ending balance Equity, Including Portion Attributable to Noncontrolling Interest Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Disposal Group, Including Discontinued Operations [Line Items] Disposal Group, Including Discontinued Operations [Line Items] Purchase price payable Business Combination, Consideration Transferred, Liabilities Incurred Business Combination [Line Items] Business Combination [Line Items] Effect of changes in tax laws or rates enacted in the current period Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Common stock, shares authorized (in shares) Common Stock, Shares Authorized Debt settled Business Combination, Consideration Transferred, Debt Settled Business Combination, Consideration Transferred, Debt Settled Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Unamortized discount Debt Instrument, Unamortized Discount (Premium), Net Schedule of the Carrying Value of the Company's Debt Instruments Schedule of Carrying Values and Estimated Fair Values of Debt Instruments [Table Text Block] Exercise Price Award Exercise Price Schedule of Restructuring and Related Costs [Table] Restructuring Cost [Table] Investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Segment Reporting [Line Items] Segment Reporting [Line Items] Floating Rate Notes due 2027 Floating Rate Senior Notes Due 2027 [Member] Floating Rate Senior Notes Due 2027 Document Quarterly Report Document Quarterly Report Insurance contracts Cash Surrender Value, Fair Value Disclosure Disposal Groups, Including Discontinued Operations [Table] Disposal Groups, Including Discontinued Operations [Table] Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Segments [Domain] Segments [Domain] Interest rate swaps Interest Rate Swap [Member] Europe Europe [Member] Exchange rate effect on cash Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Income before income taxes Consolidated income before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Debt and Other Financing Arrangements Debt Disclosure [Text Block] Repayment of debt Repayments of Long-Term Debt Noncurrent contract assets, net Contract with Customer, Asset, after Allowance for Credit Loss, Noncurrent Disposal Group Classification [Domain] Disposal Group Classification [Domain] Unamortized debt issuance costs Debt Issuance Costs, Net Schedule of Restructuring and Other Costs by Segment Restructuring and Related Costs [Table Text Block] Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Income Tax Scenario [Domain] Income Tax Scenario [Domain] Income Tax Scenario [Domain] Beginning balance Ending balance Restructuring Reserve Business Combination [Table] Business Combination [Table] Acquisitions and Divestiture Mergers, Acquisitions and Dispositions Disclosures [Text Block] Equity Component [Domain] Equity Component [Domain] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Changes in fair value included in earnings Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Gain (Loss) Included in Earnings Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Currency exchange contracts Foreign Exchange Contract [Member] Total costs and operating expenses Costs and Expenses Adoption Date Trading Arrangement Adoption Date Discontinued operation, consideration Disposal Group, Including Discontinued Operation, Consideration Cross-currency interest rate swaps designated as net investment hedge - euro Euro Member Countries, Euro Interest rate Debt Instrument, Interest Rate, Stated Percentage Dividends declared Dividends, Common Stock, Cash Total Thermo Fisher Scientific Inc. shareholders’ equity Equity, Attributable to Parent Non-cash charges Restructuring and Related Costs, Non-Cash Costs Restructuring and other costs which consist principally of gains and losses resulting from changes in estimates for significant litigation-related matters, and, in some periods, may also include gains and losses on the sale of businesses, product lines and real estate, and asset impairment charges. 4.794% 10-Year Senior Notes, Due 10/7/2035 Senior Notes 4.794% Due 2035 [Member] Senior Notes 4.794% Due 2035 Total other comprehensive income/(loss) Other Comprehensive Income (Loss), Net of Tax Including Portion Attributable to Redeemable and NonRedeemable Noncontrolling Interest Other Comprehensive Income (Loss), Net of Tax Including Portion Attributable to Redeemable and NonRedeemable Noncontrolling Interest Assets Assets [Abstract] Title Trading Arrangement, Individual Title Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Gianluca Pettiti [Member] Gianluca Pettiti Insider Trading Policies and Procedures [Line Items] Finance lease liabilities Finance Lease, Liability Other financing activities, net Proceeds from (Payment for) Other Financing Activity Allowance Accounts Receivable, Allowance for Credit Loss, Current Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Property, plant and equipment Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment, Equipment Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Contingent consideration liabilities Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Change in deferred income taxes Deferred Income Tax Expense (Benefit) Selling, general and administrative expenses Selling, General and Administrative Expense Long-term liabilities Disposal Group, Including Discontinued Operation, Liabilities, Noncurrent Supplemental Balance Sheet Information Supplemental Balance Sheet Disclosures [Text Block] Business Combination [Domain] Business Combination [Domain] Laboratory products Laboratory Products [Member] Laboratory Products Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Antidilutive stock options excluded from diluted weighted average shares (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Entity Central Index Key Entity Central Index Key Capital in excess of par value Additional Paid in Capital, Common Stock All Adjustments to Compensation All Adjustments to Compensation [Member] Corporate Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Business Combination [Axis] Business Combination [Axis] Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Effect of cross-border tax laws Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Amount Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation U.S. federal statutory tax rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount 2.01% 15-Year Senior Notes, Due 3/3/2041 (Swiss franc-denominated) Senior Notes 2.01% Due 2041 [Member] Senior Notes 2.01% Due 2041 Remaining performance obligation percentage Revenue, Remaining Performance Obligation, Percentage Other comprehensive income/(loss) before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Income Statement [Abstract] Income Statement [Abstract] Thermo Fisher Scientific Inc. shareholders’ equity: Equity, Attributable to Parent [Abstract] Document Transition Report Document Transition Report 2.02% 20-Year Senior Notes, Due 9/6/2043 (Japanese yen-denominated) Senior Notes 2.02% Due 2043 [Member] Senior Notes 2.02% Due 2043 Gain (loss) on sale of investments Gain (Loss) on Investments Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Derivatives designated as hedging instruments Designated as Hedging Instrument [Member] Elimination of intersegment revenues Intersegment Eliminations [Member] 3.20% 3-Year Senior Notes, Due 1/21/2026 (euro-denominated) Senior Notes 3.20% Due 2026 [Member] Senior Notes 3.20% Due 2026 Entity Listings [Line Items] Entity Listings [Line Items] Stock Appreciation Rights (SARs) Stock Appreciation Rights (SARs) [Member] Amount Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Contingent consideration Business Combination, Contingent Consideration, Liabilities, Fair Value Disclosures Fair value of contingent consideration liability. City Area Code City Area Code Accumulated Other Comprehensive Income/(Loss) Total AOCI Attributable to Parent [Member] 1.95% 12-Year Senior Notes, Due 7/24/2029 (euro-denominated) Senior Notes 1.95% Due 2029 [Member] 1.95% 12-Year Senior Notes, Due 7/24/2029 (euro-denominated) [Member] All Individuals All Individuals [Member] Fair value Debt Instrument, Fair Value Disclosure 0.77% 5-Year Senior Notes, Due 9/6/2028 (Japanese yen-denominated) Senior Notes 0.77% Due 2028 [Member] Senior Notes 0.77% Due 2028 Name Forgone Recovery, Individual Name Asset Rollforward Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Finished goods Inventory, Finished Goods, Net of Reserves Entity Listings [Table] Entity Listings [Table] Supplemental Income Statement Information Supplemental Income Statement Disclosure [Text Block] Supplemental Income Statement Disclosure Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] 0.832% 1.5-Year Senior Notes, Due 9/7/2026 (Swiss franc-denominated) Senior Notes 0.832% Due 2026 [Member] Senior Notes 0.832% Due 2026 Statement [Line Items] Statement [Line Items] Total assets Segment assets Assets Effective Income Tax Rate Reconciliation [Line Items] Effective Income Tax Rate Reconciliation [Line Items] Contingent consideration Business Combination, Contingent Consideration, Asset, Fair Value Disclosure Business Combination, Contingent Consideration, Asset, Fair Value Disclosure Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued 4.977% 7-Year Senior Notes, Due 8/10/2030 Senior Notes 4.977% Due 2030 [Member] Senior Notes 4.977% Due 2030 Biosciences Biosciences [Member] Biosciences Total Reportable Segments Operating Segments Operating Segments [Member] Interest expense Interest expense Interest Expense, Nonoperating Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Foreign tax effects Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent 0.80% 9-Year Senior Notes, Due 10/18/2030 (euro-denominated) Senior Notes 0.80% Due 2030 [Member] Senior Notes 0.80% Due 2030 PEO PEO [Member] 2.00% 10-Year Senior Notes, Due 10/15/2031 Senior Notes 2.00% Due 2031 [Member] Senior Notes 2.00% Due 2031 Gross amounts subject to offset in master netting arrangements not offset in the consolidated balance sheets Derivative Asset, Subject to Master Netting Arrangement, Liability Offset Other long-term liabilities Other Liabilities, Noncurrent Goodwill Goodwill Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Amount Revenue recognized that was included in the current contract liability balance at the beginning of the period Contract with Customer, Liability, Revenue Recognized Subsequent Event Type [Domain] Subsequent Event Type [Domain] Retained Earnings Retained Earnings [Member] Revolving Credit Facility Revolving Credit Facility [Member] 4.473% 7-Year Senior Notes, Due 10/7/2032 Senior Notes 4.473% Due 2032 [Member] Senior Notes 4.473% Due 2032 Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Cost of revenues adjustments Cost Of Revenues Charges (Credits) Certain charges to cost of revenues primarily for 1) the sale of inventories revalued at fair value at the date of acquisition and 2) accelerated depreciation at facilities closing due to facility consolidations. Common stock, beginning balance (in shares) Common stock, ending balance (in shares) Common Stock, Shares, Outstanding Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Award Timing Disclosures [Line Items] Cumulative translation adjustment Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Currency translation and other Restructuring Reserve, Translation and Other Adjustment Schedule of the Fair Value of the Company's Debt Instruments Fair Value, by Balance Sheet Grouping [Table Text Block] Diluted (in dollars per share) Diluted earnings per share (in dollars per share) Earnings Per Share, Diluted Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Entity Current Reporting Status Entity Current Reporting Status Net cash used in financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Total Shareholder Return Amount Total Shareholder Return Amount Intersubsegment Eliminations Intersubsegment Eliminations [Member] Derivatives designated as cash flow hedges Cash Flow Hedging [Member] Liabilities Liabilities, Fair Value Disclosure [Abstract] Life Sciences Solutions Life Sciences Solutions [Member] Life Sciences Solutions Segment Amortization of acquisition-related intangible assets Amortization of acquisition-related intangible assets Intangible Asset, Finite-Lived, Amortization Expense Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Stockholders' Equity Note [Abstract] Stockholders' Equity Note [Abstract] Schedule of Components of Purchase Price and Net Assets Acquired Business Combination [Table Text Block] Research and development expenses Research and Development Expense Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] 1.375% 12-Year Senior Notes, Due 9/12/2028 (euro-denominated) Senior Notes 1.375% Due 2028 [Member] Senior Notes 1.375% Due 2028 [Member] Financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Total revenues Revenue from Contract with Customer, Excluding Assessed Tax Property, plant and equipment, net Property, Plant, and Equipment, after Accumulated Depreciation, Depletion, and Amortization U.S. Commercial Paper Program U.S. Commercial Paper Program [Member] Borrowings under the company's U.S. commercial paper program Other adjustments Effective Income Tax Rate Reconciliation, Other Adjustments, Percent 1.76% 10-Year Senior Notes, Due 3/3/2036 (Swiss franc-denominated) Senior Notes 1.76% Due 2036 [Member] Senior Notes 1.76% Due 2036 1.75% 7-Year Senior Notes, Due 10/15/2028 Senior Notes 1.75% Due 2028 [Member] Senior Notes 1.75% Due 2028 Current assets Disposal Group, Including Discontinued Operation, Assets, Current Schedule of Changes in the Company's Accrued Restructuring Balance Schedule of Restructuring Reserve by Type of Cost [Table Text Block] Amortization of net loss included in net periodic pension cost (net of tax (provision) benefit of $0, $1, $1 and $1) Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, after Tax Laboratory Products and Biopharma Services Laboratory Products and Biopharma Services [Member] Laboratory Products and Biopharma Services Derivative contracts Derivative Asset Intangible Asset, Finite-Lived, Class [Axis] Intangible Asset, Finite-Lived, Class [Axis] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] 2.80% 20-Year Senior Notes, Due 10/15/2041 Senior Notes 2.80% Due 2041 [Member] Senior Notes 2.80% Due 2041 Underlying Securities Award Underlying Securities Amount Less: comprehensive income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Subsegments [Domain] Subsegments [Domain] Other Other Subsegment [Member] Other Subsegment Subsegments [Axis] Subsegments [Axis] 2.069% 20-Year Senior Notes, Due 10/20/2042 (Japanese yen-denominated) Senior Notes 2.069% Due 2042 [Member] Senior Notes 2.069% Due 2042 Other investing activities, net Payment for (Proceeds from) Other Investing Activity State and local income taxes, net of federal income tax effect Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Segment Reporting [Table] Segment Reporting [Table] Excise tax from stock repurchases Share Repurchase Program, Excise Tax Issuance of stock upon vesting of restricted stock units Stock Issued 1.125% 12-Year Senior Notes, Due 10/18/2033 (euro-denominated) Senior Notes 1.125% Due 2033 [Member] Senior Notes 1.125% Due 2033 Other current assets Other Assets, Current Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] All Trading Arrangements All Trading Arrangements [Member] Gain (loss) on derivative Derivative, Gain (Loss) on Derivative, Net Beginning balance Ending balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability Value Other Performance Measure, Amount Other Performance Measure, Amount Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Tax benefit on reclassification adjustment for losses on hedging instruments recognized in net income Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, Tax Operating income Segment income Operating Income (Loss) Service revenues Services Service [Member] Asia-Pacific Asia Pacific [Member] Remaining performance obligation amount Revenue, Remaining Performance Obligation, Amount Current Fiscal Year End Date Current Fiscal Year End Date 1.125% 4-Year Senior Notes, Due 3/7/2029 (Swiss franc-denominated) Senior Notes 1.125% Due 2029 [Member] Senior Notes 1.125% Due 2029 5.20% 10-Year Senior Notes, Due 1/31/2034 Senior Notes 5.20% Due 2034 [Member] Senior Notes 5.20% Due 2034 Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Clinical research Clinical Research [Member] Clinical Research Additional restructuring charges Restructuring and Related Cost, Expected Cost Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Dividends declared (in dollars per share) Common Stock, Dividends, Per Share, Declared Entity File Number Entity File Number Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Issuance of shares under stock plans Shares Issued, Value, Share-Based Payment Arrangement, after Forfeiture 1.50% 20-Year Senior Notes, Due 10/1/2039 (euro-denominated) Senior Notes 1.50% Due 2039 [Member] Senior Notes 1.50% Due 2039 Contributions from (distributions to) noncontrolling interests Noncontrolling Interest, Decrease from Distributions to Noncontrolling Interest Holders Amount reclassified from accumulated other comprehensive income/(loss) to interest expense Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, before Tax 4.902% 10-Year Senior Notes, Due 2/12/2036 Senior Notes 4.902% Due 2036 [Member] Senior Notes 4.902% Due 2036 Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Net proceeds from terminations of cross-currency interest rate swaps Proceeds From (Payments For) Cross Currency Interest Rate SwapTerminations Proceeds From (Payments For) Cross Currency Interest Rate SwapTerminations Common stock, shares issued (in shares) Common Stock, Shares, Issued Measure: Measure [Axis] Beginning balance Ending balance Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset Value Treasury stock at cost (in shares) Treasury stock beginning balance (in shares) Treasury stock ending balance (in shares) Treasury Stock, Common, Shares 1.120% 5-Year Senior Notes, Due 1/6/2030 (Swiss franc-denominated) Senior Notes 1.120% Due 2030 [Member] Senior Notes 1.120% Due 2030 Income Tax Scenario [Axis] Income Tax Scenario [Axis] Income Tax Scenario Other regions Other Regions [Member] All geographical regions not separately disclosed Equity Components [Axis] Equity Components [Axis] Currency [Axis] Currency [Axis] Product and Service [Domain] Product and Service [Domain] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Entity Interactive Data Current Entity Interactive Data Current Filtration and separation business Solventum’s Filtration and Separation Business [Member] Solventum’s Filtration and Separation Business Less: net income/(loss) attributable to noncontrolling interests and redeemable noncontrolling interest Net Income (Loss) Attributable to Noncontrolling Interest Deferred income taxes Deferred Income Tax Liabilities, Net Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Entity Small Business Entity Small Business Domestication Transaction(s) Domestication Transaction(s) [Member] Domestication Transaction(s) Comprehensive income attributable to Thermo Fisher Scientific Inc. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Tax benefit (provision) on amortization of net loss included in net periodic pension cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Reclassification Adjustment from AOCI, Tax Tax benefit (provision) on pension and other postretirement benefit liability adjustments arising during the period Other Comprehensive (Income) Loss, Defined Benefit Plan, before Reclassification Adjustment, Tax Termination Date Trading Arrangement Termination Date Weighted-average amortization period Intangible Asset, Finite-Lived, Acquired, Weighted-Average Amortization Period Effective Income Tax Rate Reconciliation [Table] Effective Income Tax Rate Reconciliation [Table] Payments Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Settlements Fair Value, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Definite-lived intangible assets Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Finite-Lived Statutory federal income tax rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Other accrued expenses Other Liabilities, Current Total derivatives, net Derivative Asset, Subject to Master Netting Arrangement, after Offset Nontaxable or nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount Other assets Other Assets, Noncurrent Document Type Document Type Acquisitions, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Fair Value, Assets and Liabilities Measured on Recurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value as of Grant Date Award Grant Date Fair Value 2.60% 10-Year Senior Notes, Due 10/1/2029 Senior Notes 2.60% Due 2029 [Member] Senior Notes 2.60% Due 2029 [Member] Reductions for tax positions of prior years Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Redemption price (as a percent) Debt Instrument, Redemption Price, Percentage 0.875% 12-Year Senior Notes, Due 10/1/2031 (euro-denominated) Senior Notes 0.875% Due 2031 [Member] Senior Notes 0.875% Due 2031 [Member] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Contract liabilities Business Combination, Recognized Liability Assumed, Deferred Revenue, Current Cumulative translation adjustment (net of tax provision (benefit) of $(41), $(207), $(14), and $(414)) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Arrangement Duration Trading Arrangement Duration Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Net proceeds from issuance of debt Proceeds from Issuance of Long-Term Debt Local Phone Number Local Phone Number Noncurrent contract liabilities Contract with Customer, Liability, Noncurrent Deferred tax benefits related to domestic transactions Effective Income Tax Rate Reconciliation, Domestication Transaction, Amount Effective Income Tax Rate Reconciliation, Domestication Transaction, Amount Consolidation Items [Axis] Consolidation Items [Axis] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Financial instruments designated as net investment hedges Net Investment Hedging [Member] Additions for tax positions of current year Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions 1.450% Notes due 2027 Senior Notes 1.45% Due 2027 [Member] 1.45% 10-Year Senior Notes, Due 3/16/2027 (euro-denominated) Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Equity in earnings/(losses) of unconsolidated entities Income (Loss) from Equity Method Investments Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Executive Category: Executive Category [Axis] Acquisitions Business Combination [Policy Text Block] Liabilities, redeemable noncontrolling interest and equity Liabilities and Equity [Abstract] Intangible Asset, Finite-Lived, Class [Domain] Intangible Asset, Finite-Lived, Class [Domain] Trade names Trade Names [Member] Schedule of Information About the Company's Financial Assets and Liabilities Measured at Fair Value on a Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Inventories Inventories Inventory, Net All Award Types Award Type [Domain] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Significant Unobservable Inputs (Level 3) Fair Value, Inputs, Level 3 [Member] Supplemental Cash Flow Information [Abstract] Supplemental Cash Flow Information [Abstract] Reclassification adjustment for losses included in net income (net of tax (provision) benefit of $0, $0, $0, and $0) Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), Reclassification, after Tax 2.06% 30-Year Senior Notes, Due 3/3/2056 (Swiss franc-denominated) Senior Notes 2.06% Due 2056 [Member] Senior Notes 2.06% Due 2056 Purchases of company common stock (in shares) Treasury Stock, Shares, Acquired Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Table] PEO Name PEO Name Geographical [Axis] Geographical [Axis] Unrealized gains/(losses) on hedging instruments Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Schedule of Short-term Debt [Table] Short-Term Debt [Table] Cash acquired Cash Acquired from Acquisition Other segment items Segment Reporting, Other Segment Item, Amount 1.6525% 4-Year Senior Notes, Due 3/7/2028 (Swiss franc-denominated) Senior Notes 1.6525% Due 2028 [Member] Senior Notes 1.6525% Due 2028 3.650% Notes due 2034 Senior Notes 3.650% Due 2034 [Member] Senior Notes 3.650% Due 2034 Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Genetic sciences Genetic Sciences [Member] Genetic Sciences Net assets acquired Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill [Abstract] Liability Class [Axis] Liability Class [Axis] 3.628% Notes due 2035 Senior Notes 3.628% Due 2035 [Member] Senior Notes 3.628% Due 2035 Purchases of company common stock Treasury Stock, Value, Acquired, Cost Method Payments Payments for Restructuring 4.80% 5-Year Senior Notes, Due 11/21/2027 Senior Notes 4.80% Due 2027 [Member] Senior Notes 4.80% Due 2027 Cash, cash equivalents and restricted cash at beginning of period Cash, cash equivalents and restricted cash at end of period Cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code 1.40% 8.5-Year Senior Notes, Due 1/23/2026 (euro-denominated) Senior Notes 1.40% Due 2026 [Member] 1.40% 8.5-Year Senior Notes, Due 1/23/2026 (euro-denominated) [Member] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Non-NEOs Non-NEOs [Member] Restricted cash included in other current assets Restricted Cash and Cash Equivalent, Current Research and safety market channel Research And Safety Market Channel [Member] Research And Safety Market Channel Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Selling, general and administrative expenses adjustments Selling General And Administrative Charges Net Certain charges/credits to selling, general and administrative expenses principally associated with acquisition accounting. Comprehensive income/(loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest 4.200% 5.5-Year Senior Notes Due 3/1/2031 Senior Notes 4.200% Due 2031 [Member] Senior Notes 4.200% Due 2031 Debt Instrument [Axis] Debt Instrument [Axis] Cash paid Payments to Acquire Businesses, Gross Stock-based compensation Share-Based Payment Arrangement, Noncash Expense 1.6524% 12-Year Senior Notes, Due 3/6/2037 (Swiss franc-denominated) Senior Notes 1.6524% Due 2037 [Member] Senior Notes 1.6524% Due 2037 Minimum consolidated interest coverage ratio Debt, Covenant, Minimum Consolidated Interest Coverage Ratio Minimum permitted Consolidated Interest Coverage Ratio (the ratio of Consolidated EBITDA to Consolidated Interest Expense) as defined in the debt or line of credit facility agreements. Disposal Group Name [Axis] Disposal Group Name [Axis] Schedule of Outstanding Debt Schedule of Debt [Table Text Block] Subsegments Consolidation Items [Domain] Subsegments Consolidation Items [Domain] 4.95% 10-Year Senior Notes, Due 11/21/2032 Senior Notes 4.95% Due 2032 [Member] Senior Notes 4.95% Due 2032 Schedule of Components of Inventories Schedule of Inventory, Current [Table Text Block] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Schedule of the Fair Value of Derivative Instruments Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Basic (in dollars per share) Basic earnings per share (in dollars per share) Earnings Per Share, Basic Purchases of company common stock Payments for Repurchase of Common Stock Contract liabilities Current contract liabilities Contract with Customer, Liability, Current Total current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Insider Trading Arrangements [Line Items] 1.8975% 20-Year Senior Notes, Due 3/7/2045 (Swiss franc-denominated) Senior Notes 1.8975% Due 2045 [Member] Senior Notes 1.8975% Due 2045 Schedule of Derivative Instruments Gains and Losses Derivative Instruments, Gain (Loss) [Table Text Block] Cost of revenues Cost of Revenue Changes in valuation allowances Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Award Type Award Type [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Accounts receivable, less allowances of $148 and $147 Accounts Receivable, after Allowance for Credit Loss, Current Retained earnings Retained Earnings (Accumulated Deficit) Microbiology Microbiology [Member] Microbiology Repayments of commercial paper Repayments of Commercial Paper Product and Service [Axis] Product and Service [Axis] All Currencies [Domain] All Currencies [Domain] Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Short-term Financing [Line Items] Short-Term Debt [Line Items] Common Stock Common Stock [Member] Intra-Entity Transactions Intra-Entity Transactions [Member] Intra-Entity Transactions Fair value of contingent consideration Business Combination, Contingent Consideration, Liability Cross-currency interest rate swaps designated as net investment hedge - Japanese yen Japan, Yen Nontaxable or nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Included in cumulative translation adjustment within other comprehensive income/(loss) Derivatives used in Net Investment Hedge, Increase (Decrease), Gross of Tax Nature of Operations and Summary of Significant Accounting Policies Organization, Consolidation and Presentation of Financial Statements Disclosure and Significant Accounting Policies [Text Block] Cover page. Cover [Abstract] Workforce reduction Restructuring and Related Cost, Number of Positions Eliminated, Period Percent Derivative Contract [Domain] Derivative Contract [Domain] Unrealized gains/(losses) on hedging instruments: Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax, Parent [Abstract] Equity Awards Adjustments Equity Awards Adjustments [Member] Long-term assets Disposal Group, Including Discontinued Operation, Assets, Noncurrent Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items] Hedging Relationship [Domain] Hedging Relationship [Domain] Total liabilities, redeemable noncontrolling interest and equity Liabilities and Equity Employee Stock Option Share-Based Payment Arrangement, Option [Member] Purchases Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Purchases Short-term obligations and current maturities of long-term obligations Less: Short-term obligations and current maturities Debt, Current Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Noncontrolling interests Equity, Attributable to Noncontrolling Interest Segments [Axis] Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Asset Class [Axis] Asset Class [Axis] Net restructuring charges incurred in 2026 Restructuring Charges Redeemable Noncontrolling Interest [Roll Forward] Redeemable Noncontrolling Interest [Roll Forward] Redeemable Noncontrolling Interest Weighted average shares Weighted Average Shares [Abstract] Weighted Average Shares Tabular List, Table Tabular List [Table Text Block] Restricted cash included in other assets Restricted Cash and Cash Equivalent, Noncurrent Other income/(expense) Other Nonoperating Income (Expense) 1.4175% 8-Year Senior Notes, Due 3/7/2033 (Swiss franc-denominated) Senior Notes 1.4175% Due 2033 [Member] Senior Notes 1.4175% Due 2033 Total Thermo Fisher Scientific Inc. Shareholders’ Equity Parent [Member] Name Awards Close in Time to MNPI Disclosures, Individual Name Equity: Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] 2.382% 30-Year Senior Notes, Due 10/18/2052 (Japanese yen-denominated) Senior Notes 2.382% Due 2052 [Member] Senior Notes 2.382% Due 2052 Purchases of investments Payments to Acquire Investments Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Fair Value Measurements Derivatives and Fair Value [Text Block] Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Derivatives, Fair Value [Line Items] Derivatives, Fair Value [Line Items] Additions due to acquisitions Unrecognized Tax Benefits, Increase Resulting from Acquisition Preferred stock, $100 par value, 50,000 shares authorized; none issued Preferred Stock, Value, Issued Adjustment to Compensation: Adjustment to Compensation [Axis] Amounts reclassified from accumulated other comprehensive income/(loss) Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Net income/(loss) Net Income (Loss) Attributable to Redeemable Noncontrolling Interest Hedging Designation [Domain] Hedging Designation [Domain] Class of Stock [Domain] Class of Stock [Domain] Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] 1.49% 20-Year Senior Notes, Due 1/6/2045 (Swiss franc-denominated) Senior Notes 1.49% Due 2045 [Member] Senior Notes 1.49% Due 2045 Hedging Designation [Axis] Hedging Designation [Axis] Credit Facility [Axis] Credit Facility [Axis] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Total assets Assets, Fair Value Disclosure Long-term obligations Long-Term Debt and Lease Obligation Name Measure Name Income Taxes Income Tax Disclosure [Text Block] Accounts payable Accounts Payable, Current Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Other net non-cash expenses Other Noncash Income (Expense) Debt Instrument [Line Items] Debt Instrument [Line Items] Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Total purchase consideration Business Combination, Consideration Transferred Capital in Excess of Par Value Additional Paid-in Capital [Member] Entity Filer Category Entity Filer Category Short-term investments Short-Term Investments 3.65% 12-Year Senior Notes, Due 11/21/2034 (euro-denominated) Senior Notes 3.65% Due 2034 [Member] Senior Notes 3.65% Due 2034 Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and Cash Equivalent Pension and other postretirement benefit liability adjustments: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Tax and Reclassification Adjustment, Attributable to Parent [Abstract] Raw materials Inventory, Raw Materials, Net of Reserves Company Selected Measure Amount Company Selected Measure Amount Derivatives not designated as hedging instruments Not Designated as Hedging Instrument [Member] 1.520% 12-Year Senior Notes, Due 1/6/2037 (Swiss franc-denominated) Senior Notes 1.520% Due 2037 [Member] Senior Notes 1.520% Due 2037 Restructuring and other costs Restructuring and other costs Restructuring And Other Costs (Income) Net Amount of restructuring charges, remediation costs and assets impairment loss; and, in some periods, may also include gains and losses on the sale of businesses, product lines and real estate. Microbiology Business Microbiology Business [Member] Microbiology Business Issuance of shares under stock plans (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Finance lease ROU assets obtained in exchange for new finance lease liabilities Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Other comprehensive income/(loss) Temporary Equity, Other Changes Current assets: Assets, Current [Abstract] Derivative contracts Derivative Liability Non-PEO NEO Non-PEO NEO [Member] Senior Notes Senior notes Senior Notes [Member] Entity Address, Address Line One Entity Address, Address Line One North America North America [Member] Benefit from/(provision for) income taxes Provision for/(benefit from) income taxes Income Tax Expense (Benefit) Net income/(loss) Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Cost of revenues Cost of Product and Service Sold Product technology Technology-Based Intangible Assets [Member] Award Timing Method Award Timing Method [Text Block] Increase/(decrease) in cash, cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Fair value – liabilities Offsetting Derivative Liabilities [Abstract] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Deferred tax assets/(liabilities) Business Combination, Recognized Liability Assumed, Deferred Tax Liability Net income attributable to Thermo Fisher Scientific Inc. Net income attributable to Thermo Fisher Scientific Inc. Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Investments Investments [Member] Proceeds from sale of property, plant and equipment Proceeds from Sale of Property, Plant, and Equipment Statement [Table] Statement [Table] Segment Reconciling Items Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment [Member] Transplant diagnostics Transplant Diagnostics [Member] Transplant Diagnostics Restatement Determination Date: Restatement Determination Date [Axis] Schedule of Changes in Each Component of Accumulated Other Comprehensive Items Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Interest income Investment Income, Interest Clario Holdings, Inc. Clario Holdings, Inc. [Member] Clario Holdings, Inc. Contingent Consideration Contingent Consideration [Member] Contingent Consideration [Member] Schedule of Contract Asset and Liability Balances Contract with Customer, Contract Asset, Contract Liability, and Receivable [Table Text Block] 4.550% 7.3-Year Senior Notes, Due 6/15/2033 Senior Notes 4.550% Due 2033 [Member] Senior Notes 4.550% Due 2033 Fair value – assets Gross amounts recognized in the consolidated balance sheets Derivative Asset, Subject to Master Netting Arrangement, before Offset Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Revenues Revenues [Abstract] 4.953% 3-Year Senior Notes, Due 8/10/2026 Senior Notes 4.953% Due 2026 [Member] Senior Notes 4.953% Due 2026 Warranty agreement (in years) Extended Warranty, Contract Manufacturing and Clinical Research Service Agreements, Duration Extended Warranty, Contract Manufacturing and Clinical Research Service Agreements, Duration Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Electron microscopy Electron Microscopy [Member] Electron Microscopy Derivative Instruments and Hedging Activities Disclosure [Abstract] UNITED STATES