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Other Comprehensive Income Loss Reclassification Adjustment From A O C I For Derivatives Securities Net Of Tax Reclassifications to income in period Litigation Settlement, Fee Expense Penalties paid Defined Benefit Plan, Expected Future Benefit Payment, Year Two 2027 Cybersecurity Risk Management, Strategy, and Governance [Abstract] Common Stock, Shares, Issued Common stock, shares issued Cybersecurity Risk Management Positions or Committees Responsible Report to Board [Flag] Cybersecurity Risk Board of Directors Oversight [Text Block] Foreign Plan [Member] Foreign Plan [Member] United Kingdom [Member] Pre tax charge. Pre Tax Charge Pre tax charge Unallocated Capital Expenditures Income Unallocated Capital Expenditures Unallocated capital expenditures (income). Statement [Table] Statement [Table] Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Gross increases – current period tax positions Right-of-use assets obtained in exchange for new operating lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Percentage of value of leases reside. 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Assets held for sale operating lease right-of use assets Debt Instrument [Line Items] Debt Instrument [Line Items] Payables and Accruals [Abstract] Current maturities of debt (Note 6) Long-Term Debt, Current Maturities Less current maturities Long-Term Debt, Current Maturities, Total Foreign Currency Contract, Asset, Fair Value Disclosure Foreign currency contracts Percentage of worldwide changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Percent Effective Income Tax Rate Reconciliation, Tax Contingency, Percent, Total Tax cuts and jobs act of 2017 deduction percentage of dividends received from distribution to earnings previously taxed. 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Liabilities held for sale operating lease liabilities Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Segment Data and Reconciliation of Segment Data to Consolidated Financial Statements and Non-GAAP Measures PHILIPPINES Philippines [Member] Pension plans postretirement and other employee benefits. Pension Plans Postretirement And Other Employee Benefits [Line Items] Pension Plans, Postretirement and Other Employee Benefits [Line Items] Schedule of Inventory, Current [Table Text Block] Composition of Inventories Derivative Instruments and Hedging Activities Disclosures [Line Items] Derivative Instruments And Hedging Activities Disclosures [Line Items] Additional Paid in Capital, Common Stock Additional paid-in capital Defined Benefit Plan, Plan Assets, Benefits Paid Benefits paid Recovery Of Penalty Recovery of penalty. Recovery of penalty Fair value measurement with unobservable inputs reconciliation recurring basis asset change in unrealized gain loss. Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Change In Unrealized Gain Loss Change in unrealized gain Number of Agreements for Amendment Number of agreements for amendment Number of agreements for amendment. Significant Accounting Policies [Text Block] Summary of Significant Accounting Policies Finite-Lived Intangible Asset, Useful Life Finite-lived intangible asset, useful life US fixed income securities. 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Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Foreign currency translation adjustments (Note 19) Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Shares, Ending Balance Shares, Beginning Balance Stock Issued Noncash financing activities issued value Interest Income (Expense), Nonoperating Interest, net (Note 6) Interest expense, net Interest expense, net Revolving Credit Facility [Member] Revolving Credit Facility [Member] Retirement Plan Type [Domain] Retirement Plan Type Liabilities, Current Total current liabilities Accrued additional remediation expenses Accrued additional remediation expenses. Accrued additional remediation expenses Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Lessee, Operating Lease, Liability, to be Paid, Year Five 2030 Revenues from External Customers and Long-Lived Assets [Line Items] U.S. federal Income Tax Paid, Federal, after Refund Received Income Tax Paid, Federal, after Refund Received, Total Pledging Purpose [Axis] Inventory, Finished Goods, Net of Reserves Finished products Effective Income Tax Rate Reconciliation [Table] Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Gross increases - tax positions in prior period Consolidated capital expenditures Payments for (Proceeds from) Productive Assets Payments for (Proceeds from) Productive Assets, Total Consolidated Capital Expenditures Segment Reporting, Reconciling Item, Excluding Corporate Nonsegment [Member] Segment Reconciling Items [Member] Consolidation Items [Domain] Consolidation Items Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Fair Value Changes within Asset Categories for which Fair Value Measurements Use Significant Unobservable Inputs (Level 3) Defined Benefit United States Plans and United Kingdom Plans Open market repurchases. 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Supply Contracts [Member] Supply Contracts [Member] Effect of cross-border tax laws Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Amount Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Amount, Total Entity Well-known Seasoned Issuer Entity Well Known Seasoned Issuer Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period, Intrinsic Value Intrinsic values of options exercised Current Foreign Tax Expense (Benefit) Current Foreign Share-Based Payment Arrangement [Text Block] Stock-based Compensation Periodic benefit cost and other comprehensive income. Periodic Benefit Cost And Other Comprehensive Income Total recognized in net periodic benefit cost and other comprehensive income Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax [Abstract] Cash flow hedges: Defined Contribution Plan [Table] Defined Contribution Plan [Table] Income Tax Reconciliation, Interest expense deduction on equity Income tax reconciliation, interest expense deduction on equity. Interest expense deduction on equity Payments of Dividends Dividends paid Payments of Dividends, Total Leases [Abstract] Stock appreciation rights (SARS) granted prior to 2017. Stock Appreciation Rights S A R S Granted Prior To Two Thousand And Seventeen [Member] SARs Granted Prior to 2017 [Member] Contract with Customer, Liability Contract liabilities Contract with Customer, Liability, Total Debt Instrument, Payment Terms Debt instrument, payment terms Amendment Flag Amendment Flag Product and Service [Domain] Product and Service Loss Contingencies [Line Items] Loss Contingencies [Line Items] The aggregate costs incurred (1) in a planned search or critical investigation aimed at discovery of new knowledge with the hope that such knowledge will be useful in developing a new product or service, a new process or technique, or in bringing about a significant improvement to an existing product or process; or (2) to translate research findings or other knowledge into a plan or design for a new product or process or for a significant improvement to an existing product or process whether intended for sale or the entity's use, during the reporting period charged to research and development projects, including the costs of developing computer software up to the point in time of achieving technological feasibility, and costs allocated in accounting for a business combination to in-process projects deemed to have no alternative future use; or 3) to perform technical services which include routine product testing, quality control and sales support service. Research Development Technical Services Expense Research, development and technical services (Note 1) Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Federal income tax provision at statutory tax rate Inventory Disclosure [Text Block] Inventories Decrease in multiple used in market-based computation result in impairment Decrease in multiple used in market-based computation resulting impairment Decrease in multiple used in market-based computation resulting impairment. Earnings Per Share, Policy [Policy Text Block] Earnings Per Share Defined Benefit Plan, Equity Securities, US [Member] U.S. Equities [Member] Disposal Group, Including Discontinued Operation, Assets, Current Disposal Group, Including Discontinued Operation, Assets, Current, Total Assets held for sale Liabilities and Equity [Abstract] Liabilities and Equity Entity Address, Postal Zip Code Entity Address, Postal Zip Code Accounts Receivable [Policy Text Block] Receivables and Credit Risk/Losses Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Net Cash Provided By Operating Activities Composition of Other Non-Current Liabilities Schedule of other liabilities noncurrent. Schedule Of Other Liabilities Noncurrent Table [Text Block] Reporting Unit [Domain] Share based compensation arrangement by share based payment award equity instruments other than options cancelled in period weighted average exercise price. Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Cancelled In Period Weighted Average Exercise Price Forfeited, Weighted Average Exercise Price Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description Capitalized interest Interest Costs Capitalized Adjustment Common Stock [Member] Common Stock [Member] Foreign tax effects, repatriation Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Amount Share-Based Payment Arrangement, Exercise of Option, Tax Benefit Actual tax benefit recognized for the tax deductions from stock based compensation Cybersecurity Risk Role of Management [Text Block] Line of credit facility maximum maturity period. Line Of Credit Facility Maximum Maturity Period Line of credit facility, Maximum maturity period Long-Term Debt, Maturity, Year One Debt matures in 2025 Nanjing Stepan Jinling Chemical Limited Liability Company. Nanjing Stepan Jinling Chemical Limited Liability Company [Member] Nanjing Stepan Jinling Chemical Limited Liability Company [Member] LIBOR [Member] LIBOR [Member] LIBOR. Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Granted, Weighted Average Exercise Price Hedging Relationship [Domain] Assets for Plan Benefits, Defined Benefit Plan Non-current asset Lessee, Operating Lease, Liability, to be Paid, Year Three 2028 Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: Accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance Bonds [Member] Surety Bond [Member] Income Tax Paid, by Individual Jurisdiction [Line Items] Payment Related To Nonqualified Plan In Current Fiscal Year Payment related to nonqualified plan in current fiscal year. Payment related to non-qualified plan, 2025 Entity Address, Address Line One Entity Address, Address Line One Deferred Tax Liabilities, Gross Deferred Tax Liabilities, Gross Deferred Tax Liabilities, Gross, Total Schedule of Share-Based Payment Award, Stock Options, Valuation Assumptions [Table Text Block] Fair Value Assumptions for Stock Options Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV Earnings Per Share [Abstract] Net Income Per Common Share Attributable to Stepan Company (Note 18): Net Income Per Common Share (Note 18): Income Tax, Policy [Policy Text Block] Income Taxes Loss Contingency Accrual Environmental losses accrual Loss Contingency Accrual, Beginning Balance Loss Contingency Accrual, Ending Balance Cybersecurity Risk Materially Affected or Reasonably Likely to Materially Affect Registrant [Flag] Supplemental Cash Flow Information [Abstract] Supplemental Cash Flow Information Foreign Currency Transactions and Translations Policy [Policy Text Block] Translation of Foreign Currencies 2023 Restructuring [Member] Two Thousand Twenty Three Restructuring [Member] Two thousand twenty three restructuring. Goodwill and Intangible Assets Disclosure [Text Block] Goodwill and Other Intangible Assets The amount of retained earnings available for dividend distribution as calculated in accordance with loan covenants. Unrestricted Retained Earnings Unrestricted retained earnings Effective income tax rate reconciliation foreign tax credit expense (benefit) nondeductible expenses. Effective Ncome Tax Rate Reconciliation Foreign Tax Credit Expense Benefit Nondeductible Expenses Non-deductible expenses and other items, net Loss Contingency [Abstract] Defined Benefit Plan, Expected Future Benefit Payment, Year Four 2029 Profit sharing contributions. Profit Sharing Contributions [Member] Profit Sharing Contributions [Member] Unsecured private placement notes two. Unsecured Private Placement Notes Two [Member] Unsecured private placement 3.86% note [Member] Operating Lease, Right-of-Use Asset Operating lease assets (Note 7) Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category Deferred Tax Assets, Gross Deferred Tax Assets, Gross Cybersecurity Risk Board Committee or Subcommittee Responsible for Oversight [Text Block] Wilmington site. Wilmington Site [Member] Wilmington Site [Member] Inventory Disclosure [Abstract] Concentration risk Payment terms. Concentration Risk Payment Terms Concentration risk Payment terms extended Land Land Document Type Document Type Notional amount of utility contracts. Notional Amount Of Utility Contracts Purchased Contract Price Goodwill and Intangible Assets, Policy [Policy Text Block] Goodwill and Other Intangible Assets Longford Mills. Longford Mills [Member] Longford Mills [Member] Income Taxes Paid, Net Cash payments of income taxes, net of refunds (Note 9) Total Cash payments of income taxes, net of refunds Gross Profit Gross Profit Collaborative Arrangement and Arrangement Other than Collaborative [Axis] Collaborative Arrangement and Arrangement Other than Collaborative Subsidiary, Ownership Percentage, Parent Ownership percentage Collaborative Arrangement and Arrangement Other than Collaborative [Domain] Collaborative Arrangement and Arrangement Other than Collaborative Entity Central Index Key Entity Central Index Key Accounts Receivable, Allowance for Credit Loss, Current Allowance, balance at ending Allowance, balance at the beginning Allowances Cybersecurity Risk Process for Informing Board Committee or Subcommittee Responsible for Oversight [Text Block] Prime Rate [Member] Prime Rate [Member] Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Net Increase (Decrease) in Cash and Cash Equivalents Subsequent Event Type [Domain] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Options/SARs to purchase shares of common stock were excluded from the computations of diluted earnings per share Increase (Decrease) in Obligation, Pension Benefits Pension liabilities Disposal Group Classification [Domain] Disposal Group Classification Common Stock, Par or Stated Value Per Share Common stock, par value Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Net current period other comprehensive income (loss) Goodwill [Line Items] Goodwill [Line Items] Fixed Income [Member] Fixed income member. Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Weighted Average Remaining Contractual Term, Ending Balance Defined Contribution Plan Disclosure [Line Items] Defined Contribution Plan Disclosure [Line Items] Retirement Plan Sponsor Location [Domain] Retirement Plan Sponsor Location Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) Foreign exchange impact Foreign Tax Jurisdiction, Other [Member] Other [Member] Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest [Abstract] Income before Taxes Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] Effective income tax rate reconciliation foreign tax credit expense (benefit) repatriation of foreign earnings. Effective Income Tax Rate Reconciliation Foreign Tax Credit Expense Benefit Repatriation Of Foreign Earnings Percentage of U.S. taxation of foreign earnings Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Number of shares of common stock issued under stock option plan Exercised, Shares Debt Disclosure [Abstract] GERMANY Germany [Member] Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Net cash flow hedge activity (Note 19) Unsecured Private Placement Notes Seven [Member] Unsecured private placement notes seven. Unsecured private placement 6.17% note [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Foreign Currency Translation Adjustments [Member] State State and Local Income Tax Expense (Benefit), Continuing Operations State and Local Income Tax Expense (Benefit), Continuing Operations, Total Settlements/State voluntary disclosure Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Settlements Supplemental Cash Flow Elements [Abstract] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income Effective Income Tax Rate Reconciliation, Tax Holiday, Percent Percentage of Philippine Economic Zone Authority tax holiday Derivative, Notional Amount Derivative notional amount Accrued Liabilities, Current Accrued liabilities (Note 14) Total accrued liabilities Payments for Legal Settlements Cash expenditures related to legal and environmental matters Ownership [Domain] Ownership Current Fiscal Year End Date Current Fiscal Year End Date Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Actual return on plan assets Schedule of Long-Term Debt Instruments [Table] Debt Instrument [Table] Legal Matters and Contingencies [Text Block] Customer Claims Other Matter Computers equipment and software. Computers Equipment And Software [Member] Computers Equipment And Software [Member] Customer Relationships [Member] Customer Relationships [Member] Entity Address, State or Province Entity Address, State or Province Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Shares, Ending Balance Shares, Beginning Balance Line of Credit Facility, Remaining Borrowing Capacity Unused Revolving credit Withholding tax rate Withholding Tax Rate Withholding tax rate. Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive Income Attributable to Stepan Company Defined Benefit Plan, Cash and Cash Equivalents [Member] Cash and Cash Equivalents [Member] Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Add weighted-average net shares from assumed exercise of options (under treasury share method) Defined Benefit Plan, Assumptions [Table Text Block] Weighted-Average Assumptions Used to Determine Benefit Obligations/Net Periodic Benefit Costs Geographical [Axis] Geographical Contract with Customer, Liability, Revenue Recognized Contract liabilities revenue recognized Increase in deferred compensation. Increase In Deferred Compensation Additional compensation expense, Increase Proceeds from Sale and Collection of Receivables Proceeds from Sale and Collection of Receivables, Total Proceeds from Sale and Collection of Receivables Petroleum Reserves [Axis] Petroleum Reserves Business Insurance Recoveries [Text Block] Insurance Recovery Tax benefit recognized threshold limit percentage. Tax Benefit Recognized Threshold Limit Percentage Percentage of Tax benefit recognized Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount State income tax provision, less applicable federal tax benefit Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount Nontaxable or nondeductible items, other Deferred compensation liability Deferred Compensation Liability, Classified, Noncurrent Deferred Compensation Liability, Classified, Noncurrent, Total Stock Issued During Period, Value, Stock Options Exercised Issuance of common stock under stock option plan Comprehensive Income, Policy [Policy Text Block] Comprehensive Income and Accumulated Other Comprehensive Income Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule Showing Tax Effects of Significant Temporary Differences Representing Deferred Tax Assets and Liabilities Other Comprehensive Income (Loss), Net of Tax [Abstract] Other Comprehensive Income (Loss): Performance Shares [Member] Performance Stock Award [Member] Concentration risk number of major customers. Concentration Risk Number Of Major Customers Single customer comprised more than 10 percent of the Company's consolidated net sales Long-Term Debt, Fair Value Fair value Two thousand sixteen restructuring. Two Thousand Sixteen Restructuring [Member] 2016 Restructuring [Member] Subsequent Event [Member] Subsequent Event [Member] Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Amounts reclassified from AOCI Other Assets, Noncurrent Other non-current assets Inventories Deferred Tax Assets, Inventory Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage Percentage of awards vesting in each year Effective Income Tax Rate Reconciliation, Repatriation of Foreign Earnings, Percent Percentage of foreign tax effects, repatriation Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Aggregate Intrinsic Value Vested or expected to vest, Aggregate Intrinsic Value Percentage of lease asset categories Percentage Of Lease Asset Categories Percentage of lease asset categories Income Tax Paid, Foreign, after Refund Received Income Tax Paid, Foreign, after Refund Received, Total Total foreign Interest Expense, Debt Interest expense Interest Expense, Debt, Total Unsecured private placement notes. Unsecured Private Placement Notes [Member] Unsecured Private Placement Notes [Member] AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name Cash [Member] Cash [Member] Treasury Stock, Common, Shares Treasury stock, shares Goodwill impairment (Note 4) Goodwill impairment Goodwill impairment Goodwill impairment (Note 4) Life to date payments for environmental remediation response activities. Payments For Site Contingencies Payment of environmental response costs Cash and Cash Equivalents [Domain] Cash and Cash Equivalents Site contingency maximum future response cost percentage. Site Contingency Maximum Future Response Cost Percentage Contribution for future response costs Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Deferred Defined Benefit Plan, Equity Securities, Non-US [Member] Non-U.S. Equities [Member] Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income Debt Instrument, Maturity Date Debt Instrument, Maturity Date Debt instrument, maturity date Defined Benefit Plan, Equity Securities [Member] Equity Securities [Member] Minimum [Member] Minimum [Member] Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Granted, Weighted Average Grant Date Fair Value Weighted-average grant-date fair values of awards granted The increase (decrease) during the reporting period in the amounts payable for environmental remediation and associated legal costs incurred but not paid. Environmental And Legal Liabilities Increase Decrease Environmental and legal liabilities Financial Instrument [Axis] Financial Instrument Assets, Current [Abstract] Current Assets: Real Estate [Member] Real Estate [Member] Amortization of Intangible Assets Amortization of Intangible Assets, Total Fair Value, Inputs, Level 3 [Member] Level 3 [Member] Liabilities, Fair Value Disclosure [Abstract] Derivative liabilities: Repayments of Other Debt Other debt repayments (Note 6) Percentage of expected long term rate of return on plan assets. Percentage Of Expected Long Term Rate Of Return On Plan Assets Expected long-term rate of return on assets Segment Reporting [Abstract] Deferred Tax Liabilities, Property, Plant and Equipment Depreciation Business Combination [Policy Text Block] Business Combinations Share based compensation arrangement by share based payment award options for forfeitures and modification in period. Share Based Compensation Arrangement By Share Based Payment Award Options For Forfeitures And Modification In Period Forfeited/Modified due to change of assumptions, Shares Forfeited/Modified due to change of assumptions, Shares Insurance recovery. Insurance Recovery [Line Items] Insurance Recovery [Line Items] Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Cash Flow Hedge Adjustments [Member] Volume derivative contract. Volume Derivative Contract Volume in derivative contract Real Estate [Member] Employee Benefit Plan, Real Estate [Member] Liabilities, Current [Abstract] Current Liabilities: Expected Payment Related To Qualified Plan In Next Fiscal Year Expected payment related to qualified plan in next fiscal year. Expected payment related to qualified plan Operating Loss Carryforwards Tax loss carryforwards Income Tax Paid, by Individual Jurisdiction [Abstract] Reporting Unit [Axis] Commitments and Contingencies Commitments and Contingencies (Note 16) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Unvested Weighted Average Grant Date Fair Value, Ending Balance Unvested Weighted Average Grant Date Fair Value, Beginning Balance Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification Out Of Accumulated Other Comprehensive Income [Table] Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, Tax Net actuarial gain (loss) arising in period, tax benefit Other Matter. Other Matter [Abstract] Income Tax Reconciliation, Nondeductible Expense, Penalties and Interest Income tax reconciliation, nondeductible expense, penalties and interest. Penalties and interest Accounts Receivable, Credit Loss Expense (Reversal) Provision Operating Lease, Liability Total lease liabilities Present value Operating Lease, Liability Goodwill, Measurement Period Adjustment Goodwill measurement period adjustment Auditor Firm ID Auditor Firm ID Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Legal Settlements Legal and environmental accruals Spread rate Debt Instrument, Basis Spread on Variable Rate Short-term debt short term current maturities debt short term current maturities debt Schedule of Goodwill [Table Text Block] Schedule of Changes in Carrying Value of Goodwill Cash Flow, Operating Activities, Lessee [Abstract] Cash paid for amounts included in the measurement of lease liabilities: Accrued Marketing Costs, Current Accrued customer rebates Long-Term Debt, Maturity, Year Two Debt matures in 2026 Assets held for sale property, prepaid assets, mostly supplies and parts Disposal Group, Including Discontinued Operation, Prepaid and Other Assets Colombia Reporting Unit [Member] Colombia reporting unit. Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Percentage of valuation allowance Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Weighted Average Remaining Contractual Term, Ending balance Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Effect of Exchange Rate Changes on Cash Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Other Changes in Plan Assets and Benefit Obligations Recognized in Other Comprehensive Income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net Income Net Income Net income Disposal Group, Including Discontinued Operation, Liabilities, Current Disposal Group, Including Discontinued Operation, Liabilities, Current, Total Liabilities held for sale Two thousand eighteen restructuring. Two Thousand Eighteen Restructuring [Member] 2018 Restructuring [Member] Cybersecurity Risk Management Positions or Committees Responsible [Text Block] Loss Contingencies [Table] Loss Contingencies [Table] Other Current Other Tax Expense Benefit Amount of other current income tax expense (benefit). Weighted Average Number of Shares Outstanding, Basic Basic Weighted-average number of shares outstanding Weighted Average Number of Shares Outstanding, Basic, Total Goodwill, Acquired During Period Goodwill acquired Delayed Draw Term Loan Credit Facility [Member] Delayed Draw Term Loan Credit Facility [Member] Delayed draw term loan credit facility. Multi currency revolving credit agreement. Multi Currency Revolving Credit Agreement [Member] Multi Currency Revolving Credit Agreement [Member] Stockholders' Equity, Other Other Duration Matching Bonds [Member] Duration matching bonds. Duration-matching Bonds [Member] European Polymers Reporting Unit [Member] European Polymers Reporting Unit. Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Summary of Variations Between the Effective and Statutory U.S. Federal Income Tax Rates Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Schedule Of Share Based Compensation Arrangements By Share Based Payment Award [Table] Schedule of Operating Leased Assets [Table] Schedule Of Operating Leased Assets [Table] Segments [Axis] Segments Surfactants [Member] Long-Lived Tangible Asset [Domain] Long-Lived Tangible Asset Foreign earnings intends to repatriate cash Foreign earnings intends to repatriate cash. Number of countries Number of Countries Number of countries. Cybersecurity Risk Process for Informing Management or Committees Responsible [Text Block] Subsequent Event Deferred Compensation Liability, Current and Noncurrent Deferred compensation liability Deferred Compensation Liability, Current and Noncurrent, Total Inventory, Raw Materials, Net of Reserves Raw materials Effective Income Tax Rate Reconciliation, Tax Credit, Percent Percentage of U.S. tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent, Total Long-Term Debt Total debt Total debt Deferred Tax Asset, Interest Carryforward Disallowed interest expense carryforwards Share based compensation arrangement by share based payment award options forfeitures and modification in period weighted average exercise price. Share Based Compensation Arrangement By Share Based Payment Award Options Forfeitures And Modification In Period Weighted Average Exercise Price Forfeited/Modified due to change of assumptions, Weighted Average Grand Date Fair Value Decommissioning costs. Decommissioning Costs [Member] Decommissioning Costs [Member] Variable Rate [Domain] Variable Rate Actuarial (income) loss Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Valuation allowance Equity, Attributable to Parent Ending Balance Beginning Balance Total Stepan Company stockholders’ equity Interest Income and Interest Expense Disclosure [Table Text Block] Schedule of Net Interest Expense Foreign Currency Contracts, Liability, Fair Value Disclosure Foreign currency contracts Long term debt without deferred loan expenses. Long Term Debt Without Deferred Loan Expenses Carrying value Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other Other accruals and reserves Statement of Stockholders' Equity [Abstract] Percentage of long term return in cash. Percentage Of Long Term Return In Cash Percentage of long term return in cash Cost of Goods and Service [Policy Text Block] Cost of Sales Type of Restructuring [Domain] Type of Restructuring Other Liabilities Disclosure [Abstract] Use of Estimates, Policy [Policy Text Block] Use of Estimates Schedule of Nonvested Share Activity [Table Text Block] Summary of Stock Award Activity Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Net actuarial (gain) loss Treasury Stock, Common [Member] Common Treasury Stock [Member] Long-Term Debt, Maturity, Year Five Debt matures in 2029 Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Unsecured private placement notes five. Unsecured Private Placement Notes Five [Member] Unsecured private placement 2.73% note [Member] Gain (Loss), Foreign Currency Transaction, before Tax Foreign Currency Transaction Gain (Loss), before Tax, Total Foreign exchange gains (losses) Entity Address, Address Line Two Entity Address, Address Line Two Fair Value Disclosures [Text Block] Fair Value Measurements Environmental and legal matters liabilities non current. Environmental And Legal Matters Liabilities Non Current Environmental and legal matters NETHERLANDS Netherlands [Member] UNITED STATES United States [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Defined Benefit Pension Plan Adjustments [Member] Income tax reconciliation nondeductible expenses and other items, net. Income Tax Reconciliation Nondeductible Expense And Other Items Net Non-deductible expenses and other items, net Noncontrolling Interest [Member] Noncontrolling Interests [Member] Schedule of Accrued Liabilities [Table Text Block] Composition of Accrued Liabilities Debt Instrument, Name [Domain] Debt Instrument, Name Other Liabilities Disclosure [Text Block] Other Non-Current Liabilities Other Assets, Current Other current assets Long-Term Debt, Maturity, Year Four Debt matures in 2028 Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Schedule of Reconciliations of Unrecognized Tax Benefits Derivative Instruments and Hedging Activities Disclosure [Abstract] Share based compensation arrangement by share based payment award equity instruments other than options exercised in period. Share Based Compensation Arrangement By Share Based Payment Award Equity Instruments Other Than Options Exercised In Period Exercised, Shares Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration] Plan Name [Domain] Plan Name Increase (Decrease) in Other Operating Assets Other current assets Increase (Decrease) in Other Operating Assets, Total Environmental Remediation Obligations [Abstract] Number of countries leases reside Number Of Countries Leases Reside Number of countries leases reside Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value Assets And Liabilities Measured On Recurring And Nonrecurring Basis [Line Items] Unrecognized tax benefits increase decrease resulting from foreign currency translation. Unrecognized Tax Benefits Increase Decreases Resulting From Foreign Currency Translation Foreign currency translation Building [Member] Building [Member] Credit Facility [Axis] Cost of Product and Service Sold Cost of Sales Cost of Goods and Services Sold, Total Proceeds from (Repayments of) Lines of Credit Revolving debt and bank overdrafts, net (Note 6) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average Exercise Price Exercisable, Weighted Average Exercise Price Current State and Local Tax Expense (Benefit) State Schedule of Expected Benefit Payments [Table Text Block] Estimated Future Benefit Payments Cybersecurity Risk Management Expertise of Management Responsible [Text Block] Debt Securities [Member] Debt Securities [Member] Defined Benefit Plan, Expected Future Employer Contributions, Next Fiscal Year Expected payment related to qualified plan Restructuring Plan [Axis] Restructuring Plan Supply Commitment Arrangement [Domain] Supply Commitment Arrangement Other Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Foreign Tax Jurisdiction [Member] Defined Benefit Plan, Equity Securities, Common Stock, Employer, Related Party [Member] Employer Securities [Member] Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount Prior years return to provision true-up Pension Plan [Member] Defined Contribution Plans [Member] Property, Plant and Equipment, Policy [Policy Text Block] Property, Plant and Equipment Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, after Tax Net actuarial (loss) arising in period (net of tax benefit of $438, tax benefit of $2,044 and tax benefit of $508 for 2025, 2024 and 2023, respectively) Foreign Exchange Contract [Member] Foreign exchange contracts [Member] Entity Address, City or Town Entity Address, City or Town Other retirement obligation. Other Retirement Obligation Other retirement obligation Defined Contribution Plan Disclosures [Table Text Block] Defined Contribution Expenses for Company's Qualified Defined Contribution Plans and Statutory Profit Sharing Contributions Number of Reportable Segments Number of reportable segments Percentage of union and non-union employees eligible for either statutory or Company's sponsored profit sharing contributions. Percentage Of Union And Non Union Employees Eligible For Either Statutory Or Companys Sponsored Profit Sharing Contributions Percentage of union and non-union employees eligible for either statutory or Company's sponsored profit sharing contributions Security Exchange Name Security Exchange Name Deferred Other Tax Expense (Benefit) Other Credit Facility [Domain] Demand deposits and certifates of deposit. Demand Deposits And Certifates of Deposit [Member] Demand Deposits And Certifates of Deposit [Member] Europe [Member] Europe [Member] Indefinite-Lived Intangible Assets (Excluding Goodwill) Indefinite-life intangible assets Indefinite-Lived Intangible Assets (Excluding Goodwill), Total Indefinite-Lived Intangible Assets (Excluding Goodwill), Beginning Balance Indefinite-Lived Intangible Assets (Excluding Goodwill), Ending Balance Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Percentage of other Property, Plant and Equipment, Gross Property, Plant and Equipment, Gross Property, Plant and Equipment, Gross, Beginning Balance Property, Plant and Equipment, Gross, Ending Balance Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Current Nature of operations. Nature Of Operations Policy [Text Block] Nature of Operations Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Consolidated income before income taxes Operating Income Income Before Provision for Income Taxes Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Number Vested or expected to vest, Shares Proceeds from Other Debt Other debt borrowings (Note 6) Compensation Related Costs [Abstract] Pledging Purpose [Domain] Contract with Customer, Duration [Domain] Unallocated Corporate Expenses Unallocated corporate expenses. Unallocated Corporate Expenses Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Percentage of Foreign income taxed at different rates Polymers. Polymers [Member] Polymer Segment [Member] Polymers [Member] Inventory, Net Inventories (Note 5) Total inventories Deferred Tax Assets, Goodwill and Intangible Assets Amortization of intangibles Interest Paid, Excluding Capitalized Interest, Operating Activity Cash payments of interest Statistical Measurement [Domain] Statistical Measurement Remeasurement adjustment related to the Tax Act . Remeasurement Adjustment Related To The Tax Act Remeasurement adjustment related to the Tax Act CIC credit agreement. CIC Credit Agreement [Member] CIC Credit Agreement [Member] MEXICO Mexico [Member] Assets, Current Total current assets Early termination of lease expenses. Early Termination Of Lease Expenses [Member] Early Termination of Lease Expenses [Member] Share-Based Payment Arrangement, Expense Compensation expenses Site Contingency [Line Items] Site Contingency [Line Items] Document Period End Date Document Period End Date Other Income and Expenses [Abstract] Deferred tax assets tax deferred expense reserves and accruals allowance for doubtful accounts and rebate reserves. Deferred Tax Assets Tax Deferred Expense Reserves And Accruals Allowance For Doubtful Accounts And Rebate Reserves Bad debt and rebate reserves Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV Defined Contribution Plan, Cost Defined contribution plan expense Total defined contribution expense ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Retirement contributions. 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Finite-Lived Intangible Asset, Expected Amortization, Year Three For the year ended December 31, 2028 Income Tax Expense (Benefit) Provision for Income Taxes (Note 9) Tax benefit Total income tax expense Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Percentage of target allocation for investment category Common Stock, Dividends, Per Share, Cash Paid Common stock Defined benefit plan percentage of second preceding year asset gain or loss considered to calculate expected return on plan assets. Defined Benefit Plan Percentage Of Second Preceding Year Asset Gain Or Loss Considered To Calculate Expected Return On Plan Assets Assets gains or losses added for second preceding year Capital expenditures Payments to Acquire Productive Assets Payments to Acquire Productive Assets, Total Segment Capital Expenditures Defined Benefit Plan, Expected Future Benefit Payment, Year Five 2030 Percentage of deferred compensation liblity related to performance common stock. Percentage Of Deferred Compensation Liblity Related To Performance Common Stock Percentage of deferred compensation liability related to performance common stock Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Share Based Compensation Arrangement By Share Based Payment Award [Line Items] Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Surfactants. Surfactants [Member] Surfactants Segment [Member] Surfactants [Member] Disposal Group Classification [Axis] Disposal Group Classification Other, Net Other Income and Other Expense Disclosure [Text Block] Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Prior service cost Net Income (Loss) Attributable to Parent, Diluted Net income attributable to Stepan Company Net Income (Loss) Attributable to Parent, Diluted, Total Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss (Note 19) Accumulated Other Comprehensive Income (Loss), Net of Tax, Total Consolidation Items [Axis] Consolidation Items Federal Income Tax Expense (Benefit), Continuing Operations Federal Income Tax Expense (Benefit), Continuing Operations, Total U.S. federal Payments to Acquire Property, Plant, and Equipment Capital expenditures Expenditures for property, plant and equipment Payments to Acquire Property, Plant, and Equipment, Total Payment for (Proceeds from) Other Investing Activity Other, net Gain (Loss) on Investments Gain (Loss) on Investments, Total Realized and unrealized (gains) on long-term investments Realized and unrealized gains on investments Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Granted, Shares Capitalized environmental expenditures depreciation period. Capitalized Environmental Expenditures Depreciation Period Capitalized Environmental expenditures depreciation period Assets Assets Total Assets Customer lists and relationships. Customer Lists And Relationships [Member] Customer Lists/relationships [Member] Inventory, Policy [Policy Text Block] Inventories Income Tax Paid, State and Local, after Refund Received Income Tax Paid, State and Local, after Refund Received, Total Total U.S. state and local Income Statement [Abstract] Retirement Plan Name [Domain] Retirement Plan Name Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Employee Compensation Deferred compensation Schedule Of Restructuring And Related Costs [Table] Restructuring Cost [Table] Gross (decreases) - tax positions in prior period Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Share-Based Payment Arrangement [Policy Text Block] Stock-Based Compensation Amortization of net actuarial (gain) loss Defined Benefit Plan, Amortization of Gain (Loss) Deferred Income Tax Expense (Benefit) Deferred income taxes Total deferred income tax (benefit) expense Lease, Cost [Abstract] Lease Cost Performance RSUs vested Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Vested, Shares Schedule of Allocation of Plan Assets [Table Text Block] Company's Asset Allocations for its U.S. and U.K Pension Plans Earnings Per Share, Diluted [Abstract] Computation of Diluted Earnings per Share Business Combination [Abstract] Earnings Per Share, Diluted Diluted Diluted earnings per share Earnings Per Share, Diluted, Total Operating Segments [Member] Operating Segments [Member] Finite-Lived Intangible Asset, Expected Amortization, Year Five For the year ended December 31, 2030 Long-Term Contract with Customer [Member] Long-Term [Member] Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount Foreign tax effects City Area Code City Area Code Noncash financing activities includes shares issued. Noncash Financing Activities Includes Shares Issued Noncash financing activities shares issued Defined Benefit Plan, Amounts for Asset (Liability) Recognized in Statement of Financial Position Net amount recognized Other Comprehensive Income (Loss) Other Comprehensive Income (Loss), Net of Tax Other comprehensive income Deferred Tax Assets, Tax Deferred Expense, Compensation and Benefits, Pensions Pensions Auditor Name Auditor Name Debt Instrument, Face Amount Aggregate principal amount in debt issued and sold Buildings and Improvements, Gross Buildings and improvements Line of Credit Facility, Maximum Borrowing Capacity Borrowing capacity Business Combination [Line Items] Business Acquisition [Line Items] Effective income tax rate reconciliation share based compensation excess tax benefit percentage. Effective Income Tax Rate Reconciliation Share Based Compensation Excess Tax Benefit Percentage Percentage of stock based compensation, excess tax benefits Defined Benefit Plan [Table] Schedule Of Defined Benefit Plans Disclosures [Table] Deferred Tax Assets, Tax Credit Carryforwards Tax credit carryforwards Tax credit carryforwards Deferred Tax Assets, Tax Credit Carryforwards, Total Effective Income Tax Rate Reconciliation, Nondeductible Expense, Impairment Losses, Percent Percentage of goodwill impairment Know how. Know How [Member] Know-how [Member] Recovery of litigation settlement expense Litigation Settlement, Gain Variable Lease, Cost Variable lease cost Effective Income Tax Rate Reconciliation, Interest expense deduction on equity Effective income tax rate reconciliation, interest expense deduction on equity. Percentage of interest expense deduction on equity Operating Lease, Weighted Average Remaining Lease Term Weighted-average remaining lease term-operating leases Changes in Projected Benefit Obligations, Fair Value of Plan Assets, and Funded Status of Plan [Table Text Block] Obligations and Funded Status Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Lease, Cost Total lease cost Number of foreign subsidiaries. Number Of Foreign Subsidiaries Number of foreign subsidiaries Supplemental executive retirement plan liability. Supplemental Executive Retirement Plan Liability Supplemental plan liability balances Percentage of US based union and non union employees eligible for either Statutory or companys sponsored profit sharing contributions. Percentage Of U S Based Union And Non Union Employees Eligible For Either Statutory Or Companys Sponsored Profit Sharing Contributions Percentage of us based union and non-union employees eligible for either statutory or Company's sponsored profit sharing contributions Retirement Plan Name [Axis] Retirement Plan Name Letter of Credit [Member] Letter of Credit [Member] Cash and Cash Equivalents, Policy [Policy Text Block] Cash and Cash Equivalents Effective Income Tax Rate Reconciliation, Nondeductible Expense, Penalties and Interest Effective income tax rate reconciliation, nondeductible expense, penalties and interest. Percentage of penalties and interest Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax Amortization of actuarial loss included in pension expense, tax Percentage of premium estimated return for equities and properties to risk free rate. Percentage Of Premium Estimated Return For Equities And Properties To Risk Free Rate Percentage of premium estimated return for equities and properties to risk free rate Unsecured private placement notes four. Unsecured Private Placement Notes Four [Member] Unsecured private placement 2.37% note [Member] Property, Plant and Equipment, Net Property, plant and equipment, net BRAZIL Brazil [Member] Defined Benefit Plan, Expected Future Benefit Payment, Year Three 2028 Deferred Foreign Income Tax Expense (Benefit) Foreign Impairment expenses Impairment of Intangible Assets, Finite-Lived Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable, Number Exercisable, Shares Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Cash and Cash Equivalents at End of Year Cash and Cash Equivalents at Beginning of Year Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total Operating Income (Loss) Operating Income Operating income Goodwill, Foreign Currency Translation, Gain (Loss) Foreign currency translation Federal Ministry of Finance, Germany [Member] Germany - Federal [Member] Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Discount rate Retained Earnings [Member] Retained Earnings [Member] Balance of the trust assets. Balance Of Trust Assets Balance of trust assets Stock Issued During Period, Shares, Employee Benefit Plan Treasury stock distributed under deferred compensation plan Cash and Cash Equivalents [Axis] Cash and Cash Equivalents Defined Benefit Plan, Pension Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation Projected benefit obligation Stepan Philippines Quaternaries, Inc.[Member] Stepan Philippines Quaternaries, Inc. Share-Based Payment Arrangement, Noncash Expense Stock-based compensation Share-Based Payment Arrangement, Noncash Expense, Total Restructuring and Related Cost, Number of Positions Eliminated Number positions eliminated Unallocated assets. Unallocated Assets Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax Amortization of prior service cost included in pension expense, tax Operating Lease, Weighted Average Discount Rate, Percent Weighted-average discount rate-operating leases Operating Lease, Liability, Noncurrent Non-current operating lease liability (Note 7) Non-current operating lease liabilities Fair Value, Inputs, Level 1 [Member] Level 1 [Member] Maximum amount not indefinitely reinvested Maximum amount not indefinitely reinvested. Equity securities pooled pension funds. Equity Securities Pooled Pension Funds [Member] Pooled Pension Funds [Member] Class of Stock [Line Items] Class Of Stock [Line Items] Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Net Cash Provided By (Used In) Financing Activities Lease, Cost [Table Text Block] Schedule of Lease Cost Included in Cost of Sale and Operating Expenses Unamortized Debt Issuance Expense Unamortized debt issuance cost Auditor Location Auditor Location Deferred Income Tax Liabilities, Net Deferred income taxes (Note 9) Non-current deferred tax liabilities Amortization of net actuarial gain (loss) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Actuarial loss Nonoperating Income (Expense) [Abstract] Other Income (Expense): Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Asset, Sales Sale proceeds (benefit payments) Derivative Contract [Domain] Derivative Contract Goodwill [Table] Schedule Of Goodwill [Table] Stock appreciation rights (SARS) granted in 2017. Stock Appreciation Rights S A R S Granted In Two Thousand And Seventeen [Member] SARs Granted in 2017 [Member] Deferred Tax Assets, Operating Loss Carryforwards, Foreign Net operating loss carryforwards Income Tax Jurisdiction [Domain] Income tax reconciliation foreign tax credit expense benefit repatriation of foreign earnings. Income Tax Reconciliation Foreign Tax Credit Expense Benefit Repatriation Of Foreign Earnings U.S. taxation of foreign earnings Entity Interactive Data Current Entity Interactive Data Current Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category Deferred Tax Liabilities, Gross [Abstract] Deferred Tax Liabilities: Increase (Decrease) in Contract with Customer, Liability Deferred revenues Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Cash Flows From Operating Activities Furniture and Fixtures [Member] Furniture and Fixtures [Member] Share-Based Payment Arrangement, Stock Appreciation Right, Activity [Table Text Block] Summary of SARs Activity Two thousand nineteen restructuring. Two Thousand Nineteen Restructuring [Member] 2019 Restructuring [Member] Contract with Customer, Asset, after Allowance for Credit Loss Contract assets Contract with Customer, Asset, after Allowance for Credit Loss, Total Share-Based Payment Arrangement, Expense, Tax Benefit Income tax benefit recognized in the income statement for share-based compensation arrangements Entity Tax Identification Number Entity Tax Identification Number Equity, Including Portion Attributable to Noncontrolling Interest [Abstract] Equity (Note 10): Debt Instrument, Term Maturity Dates Two thousand and twenty one acquisition. Two Thousand And Twenty One Acquisition [Member] 2021 Acquisitions [Member] Lake Providence Louisiana [Member] Lake providence louisiana member. Interest Income, Other Interest income Construction in Progress, Gross Construction in progress Local Phone Number Local Phone Number Options and stock appreciation rights. Options And Stock Appreciation Rights [Member] Options and Stock Appreciation Rights (SARs) [Member] Options and Stock Appreciation Rights (SARs) [Member] Line of credit including term loan. Line of Credit Including Term Loan Outstanding borrowings, including term loan Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income Loss [Line Items] Net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Net periodic benefit cost Net periodic benefit cost Demand Deposits [Member] Short-Term Lease, Cost Short-term lease cost CHINA China [Member] Weighted Average Number of Shares Outstanding, Diluted [Abstract] Shares Used to Compute Net Income Per Common Share Attributable to Stepan Company (Note 18): Shares Used to Compute Net Income Per Common Share (Note 18): Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Amortization of actuarial loss included in pension expense (net of tax expense of $89, $104 and $99 for 2025, 2024 and 2023, respectively) Auditor Opinion [Text Block] Restructuring expenses Restructuring Costs Restructuring Costs, Total Trademarks [Member] Trademarks [Member] Long-Lived Assets Long-lived assets Effective income tax rate reconciliation tax cuts and jobs act of 2017 transition tax on accumulated foreign earnings increase percent. Effective Income Tax Rate Reconciliation Tax Cuts And Jobs Act of 2017 Transition Tax on Accumulated Foreign Earnings Increase Percent Increase in effective tax rate Accounting Policies [Abstract] Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other comprehensive income (loss) before reclassifications Disaggregation of Revenue [Line Items] Disaggregation Of Revenue [Line Items] Net sales Net Sales (Note 1) Net Sales Insurance Recoveries Insurance recovery proceeds Earnings Per Share, Basic, by Common Class, Including Two-Class Method [Table] Schedule Of Earnings Per Share Basic By Common Class [Table] Lessee, Operating Lease, Liability, to be Paid, Year Four 2029 Maturity date of current interest swap contract Maturity Date Of Current Interest Swap Contract Maturity date of current interest swap contract. Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Shares available for grant under the 2011 plan Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Weighted average period for amortization of unrecognized compensation cost Incremental tax expense Deferred Tax Liabilities, Deferred Expense Deferred Tax Liabilities, Deferred Expense, Total SARs [Member] Noncash or part noncash investing activities payables incurred for property, plant and equipment expenditures unpaid. Noncash Or Part Noncash Investing Activities Payables Incurred For Property Plant And Equipment Expenditures Unpaid Noncash investing activities, payables incurred for property, plant and equipment expenditures, unpaid Stock, Class of Stock [Table] Schedule Of Stock By Class [Table] Goodwill, Impaired, Accumulated Impairment Loss Accumulated impairment loss, Ending Balance Accumulated impairment loss, Beginning Balance Derivatives, Reporting of Derivative Activity [Policy Text Block] Derivative Instruments Defined benefit plan percentage of preceding year asset gain or loss considered to calculate expected return on plan assets. Defined Benefit Plan Percentage Of Preceding Year Asset Gain Or Loss Considered To Calculate Expected Return On Plan Assets Assets gains or losses added for prior year Entity Emerging Growth Company Entity Emerging Growth Company Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Outstanding, Weighted Average Remaining Contractual Term Vested or expected to vest, Weighted Average Remaining Contractual Term President and chief executive officer. President and Chief Executive Officer [Member]