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Statement - Condensed Consolidated Statements of Equity (Parenthetical) (Unaudited) link:presentationLink link:calculationLink link:definitionLink 995455 - Disclosure - Basis of Presentation link:presentationLink link:calculationLink link:definitionLink 995465 - Disclosure - Segment Reporting link:presentationLink link:calculationLink link:definitionLink 995475 - Disclosure - Earnings Per Share link:presentationLink link:calculationLink link:definitionLink 995485 - Disclosure - Goodwill link:presentationLink link:calculationLink link:definitionLink 995495 - Disclosure - Other Intangible Assets link:presentationLink link:calculationLink link:definitionLink 995505 - Disclosure - Pension and Post-Employment Benefits link:presentationLink link:calculationLink link:definitionLink 995515 - Disclosure - Income Taxes link:presentationLink link:calculationLink link:definitionLink 995525 - Disclosure - Long-Term Debt link:presentationLink link:calculationLink link:definitionLink 995535 - Disclosure - 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Disclosure - Goodwill - Summary of Goodwill (Detail) link:presentationLink link:calculationLink link:definitionLink 995795 - Disclosure - Other Intangible Assets - Summary of Other Intangible Assets (Detail) link:presentationLink link:calculationLink link:definitionLink 995805 - Disclosure - Other Intangible Assets - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995815 - Disclosure - Pension and Post-Employment Benefits - Plan Net Pension Credit (Detail) link:presentationLink link:calculationLink link:definitionLink 995825 - Disclosure - Pension and Post-Employment Benefits - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995835 - Disclosure - Income Taxes - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995845 - Disclosure - Long-Term Debt - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995855 - Disclosure - Plant Closure Provisions - Movements in Plant Closure and Restructuring Provisions (Detail) link:presentationLink link:calculationLink link:definitionLink 995865 - Disclosure - Plant Closure Provisions - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995875 - Disclosure - Fair Value Measurements - Carrying Amount and Fair Values of the Company's Assets and Liabilities Measured on a Recurring Basis (Detail) link:presentationLink link:calculationLink link:definitionLink 995885 - Disclosure - Fair Value Measurements - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 995895 - Disclosure - Derivative Instruments and Risk Management - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995905 - Disclosure - Contingencies - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995915 - Disclosure - Stock-Based Compensation Plans - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995925 - Disclosure - Stock-Based Compensation Plans - Summary of Transactions of the Company's Share Based Compensation (Detail) link:presentationLink link:calculationLink link:definitionLink 995935 - Disclosure - Stock-Based Compensation Plans - Summary of Transactions of the Share Based Compensation Plans (Detail) link:presentationLink link:calculationLink link:definitionLink 995945 - Disclosure - Reclassifications Out of Accumulated Other Comprehensive Loss - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995955 - Disclosure - Reclassifications Out of Accumulated Other Comprehensive Loss - Changes in Accumulated Other Comprehensive Loss (Detail) link:presentationLink link:calculationLink link:definitionLink 995965 - Disclosure - Related Party Transactions - Additional Information (Detail) link:presentationLink link:calculationLink link:definitionLink 995975 - Disclosure - Subsequent Events (Additional Information) (Details) link:presentationLink link:calculationLink link:definitionLink Proceeds from Sale of Property, Plant, and Equipment, Total Proceeds from Sale of Property, Plant, and Equipment Proceeds on disposal of property, plant and equipment Retirement Plan Type [Axis] Oilfield services. Oilfield Services [Member] Oilfield Services [Member] Segments [Domain] Segments [Domain] Restructuring Reserve Restructuring Reserve, Total Ending Balance Beginning Balance Entity Incorporation, State or Country Code Movements On Defined Benefit Pension Plans Movements on defined benefit pension plans. Movements on defined benefit pension plans Adjustment to fair value of contingent consideration Adjustment to fair value of contingent consideration Business Combination, Contingent Consideration, Change in Contingent Consideration, Liability, Increase (Decrease) Equity [Abstract] Entity Current Reporting Status Goodwill, Gross Gross cost, ending balance Gross cost, beginning balance Operating Expenses [Abstract] Operating expenses: Common Stock, Shares Authorized Common stock, shares authorized Defined benefit plan net periodic other benefit cost. Defined Benefit Plan Net Periodic Other Benefit Cost Net periodic benefit/(cost) Document Fiscal Period Focus Entity Shell Company Cash and Cash Equivalents, at Carrying Value, Total Cash and Cash Equivalent Cash and cash equivalents Defined Benefit Plan, Benefit Obligation Defined Benefit Plan, Benefit Obligation, Ending Balance Defined Benefit Plan, Benefit Obligation, Beginning Balance Projected Benefit Obligation Goodwill Disclosure [Text Block] Goodwill Common Stock, Shares, Issued Common stock, shares issued Foreign Plan [Member] Statement [Table] Statement [Table] Increase (Decrease) in Prepaid Expense Prepaid expenses Share-Based Payment Arrangement, Disclosure [Abstract] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Granted Increase (Decrease) in Receivables, Total Increase (Decrease) in Receivables Trade and other accounts receivable Statement [Line Items] Statement [Line Items] Treasury Stock, Value, Acquired, Cost Method Treasury stock repurchased Business Combination [Domain] Entity Filer Category Liabilities and Equity Total liabilities and equity Debt Instrument [Line Items] Debt Instrument [Line Items] Restructuring Type [Axis] Restructuring Type [Axis] Repayment of historical cost Severance Costs Quimica Geral S A [Member] Quimica Geral S A. Restructuring and Related Costs [Table Text Block] Movements in Plant Closure and Restructuring Provisions Derivative [Line Items] Derivative [Line Items] Cash and Cash Equivalents, Fair Value Disclosure Cash and cash equivalents Other performance chemicals. Other Performance Chemicals [Member] Other [Member] Subsequent Event [Line Items] Refinery and performance. Refinery And Performance [Member] Refinery and Performance [Member] Goodwill, Ending Balance Goodwill, Beginning Balance Goodwill, Total Goodwill Goodwill Stock Options Plan [Member] Asset Retirement Obligation, Accretion Expense Accretion expense recognized Inventory, Finished Goods, Gross Finished goods Other comprehensive income/(loss), before tax Other Comprehensive Income (Loss), before Tax Additional Paid in Capital, Common Stock Additional paid-in capital Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Number of shares, Granted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Summary of Earnings Per Share Increase (Decrease) in Other Operating Assets and Liabilities, Net, Total Increase (Decrease) in Other Operating Assets and Liabilities, Net Other assets and liabilities Earnings Per Share, Basic, Total Earnings Per Share, Basic Basic Earnings per share, basic: Retirement Benefits [Text Block] Pension and Post-Employment Benefits Changes in cumulative translation adjustment, net of tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Changes in cumulative translation adjustment, net of tax of $0.5 million, $1.0 million, $(0.2) million and $2.2 million, respectively Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested, Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Vested Interest Income (Expense), Nonoperating Interest income, net Revolving Credit Facility [Member] Revolving Credit Facility [Member] Revolving Loan Facility [Member] Retirement Plan Type [Domain] Liabilities, Current Total current liabilities Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] Adjustments to reconcile net income attributable to Innospec to net cash provided by operating activities: Hedging Designation [Domain] Hedging Designation [Domain] Subsegments [Axis] Subsegments [Axis] Home care. Home Care [Member] Home Care [Member] Refinancing costs Payments of Debt Issuance Costs Refinancing costs Consolidation Items [Domain] Consolidation Items [Domain] Equity, Attributable to Parent [Abstract] Equity: Entity Small Business Hedging Designation [Axis] Hedging Designation [Axis] Retained Earnings (Accumulated Deficit), Total Retained Earnings (Accumulated Deficit) Retained earnings Other Commitments [Line Items] Accretion Expense Accretion charge Share-Based Payment Arrangement [Text Block] Stock-Based Compensation Plans Organization, Consolidation and Presentation of Financial Statements [Abstract] Payments of Dividends Payments of Dividends, Total Dividend paid Dividend paid Inventory Valuation Reserves Inventory allowances Reduction in the fair value of the expected payable Reduction In The Fair Value Of The Expected Payable Reduction in the fair value of the expected payable. Amendment Flag Guarantor obligations, fixed maturity remaining term. Guarantor Obligations Fixed Maturity Remaining Term Fixed maturity guarantee remaining term Liabilities and Equity [Abstract] Liabilities and Equity Entity Address, Postal Zip Code Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Payments to Develop Software Internally developed software Payments to Develop Software Segment Reporting, CODM, Profit (Loss) Measure, How Used, Description Common Stock [Member] Common Stock [Member] Assets for Plan Benefits, Defined Benefit Plan Pension asset Portion at Fair Value Measurement [Member] Portion at Fair Value Measurement [Member] [Default] Entity Address, Address Line One Deferred Income Taxes and Tax Credits, Total Deferred Income Taxes and Tax Credits Deferred taxes Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Earnings Per Share [Abstract] Earnings per share: Operating Lease, Right-of-Use Asset Operating lease right-of-use assets Operating lease right-of-use assets Defined Benefit Plan, Plan Assets, Category [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Guarantor Obligations, Current Carrying Value Guarantees Income taxes Increase (Decrease) in Income Taxes Net Income (Loss) Attributable to Noncontrolling Interest Share of net income Less: Net income attributable to noncontrolling interests Share of net income Share of net income Document Type Gross Profit Gross profit Gross profit/(loss) Gross profit Entity Central Index Key Accounts Receivable, Allowance for Credit Loss, Current Allowances for doubtful accounts Schedule of Segment Reporting Information Related to Selling, General and Administrative Expense and Research and Development Expense, by Segment [Table Text Block] Schedule of segment reporting information related to selling, general and administrative expense and research and development expense, by segment. Summary of Segment Reporting related to Selling, General and Administrative Expense and Research and Development Expense Due within one year Restructuring Reserve, Current Current portion of plant closure provisions Due within one year Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Net change in cash and cash equivalents Subsequent Event Type [Domain] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Average number of anti-dilutive options excluded from the calculation of diluted earnings per share Restructuring Reserve, Period Increase (Decrease) Charge for the period Contingent Consideration Adjustment To Fair Value Adjustment to fair value of contingent consideration. Adjustment to fair value of contingent consideration Common Stock, Par or Stated Value Per Share Common stock, par value Goodwill [Line Items] Goodwill [Line Items] Acquisition-related contingent consideration Asset Acquisition, Contingent Consideration, Liability Asset Acquisition, Contingent Consideration, Liability, Total Retirement Plan Sponsor Location [Domain] Retirement Plan Sponsor Location [Domain] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested, Number of Shares Number of shares , Ending balance Number of shares, Begining balance Debt Disclosure [Abstract] GERMANY Foreign Currency Translation Items [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Derivative [Table] Derivative [Table] Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block] Fair Value Measurements Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Estimate of Fair Value Measurement [Member] Fair Value [Member] Accrued Liabilities, Current, Total Accrued Liabilities, Current Accrued liabilities Cost of Sales [Member] Cost of Sales [Member] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Current Fiscal Year End Date Schedule of Long-Term Debt Instruments [Table] Schedule of Long-term Debt Instruments [Table] Document Quarterly Report Customer Relationships [Member] Customer Relationships [Member] Entity Address, State or Province Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Dilutive effect of stock options and awards Inventory, Raw Materials, Gross Raw materials Stockholders' Equity Attributable to Noncontrolling Interest, Ending Balance Stockholders' Equity Attributable to Noncontrolling Interest, Beginning Balance Stockholders' Equity Attributable to Noncontrolling Interest, Total Equity, Attributable to Noncontrolling Interest Non-controlling interest Remediation. Remediation [Member] Remediation [Member] Deferred Income Tax Assets, Net Deferred tax assets Subsequent Event [Member] Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Total reclassifications Amounts reclassified from AOCL Non-financial liabilities. Non Financial Liabilities [Abstract] Non-financial liabilities (Level 3 measurement): Tax related to cumulative translation adjustment Tax related to cumulative translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, Net of Tax Other Assets, Noncurrent Other non-current assets Stock equivalent units fair value disclosure. Stock Equivalent Units Fair Value Disclosure Stock equivalent units Other Commitments [Domain] Other Commitments [Domain] AOCI Attributable to Parent [Member] Accumulated Other Comprehensive Loss [Member] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Treasury stock, shares Treasury Stock, Common, Shares Other Commitments [Table] Other Commitments [Table] Selling, General and Administrative Expense, Total Selling, General and Administrative Expense Selling, general and administrative Reclassification out of Accumulated Other Comprehensive Income [Domain] Reclassification out of Accumulated Other Comprehensive Income [Domain] Derivatives asset Derivative Asset, Subject to Master Netting Arrangement, before Offset Assets, Current [Abstract] Current assets: Income tax income/(expense) related to other comprehensive income Income tax income/(expense) related to other comprehensive income Other Comprehensive Income (Loss), Tax Other Comprehensive Income (Loss), Tax, Total Amortization expense Amortization of Intangible Assets Amortization expense Fair Value, Inputs, Level 3 [Member] Significant Unobservable Inputs (Level 3) [Member] Segment Reporting [Abstract] Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Carrying Amount and Fair Values of the Company's Assets and Liabilities Measured on a Recurring Basis Current liabilities: Liabilities, Current [Abstract] Personal care. Personal Care [Member] Personal Care [Member] Selling, General and Administrative Expense and Research and Development Expense Selling, general and administrative expense and research and development expense. Total selling, general and administrative expenses and research and development expenses Total selling, general and administrative expenses and research and development expenses Restructuring and Related Activities Disclosure [Text Block] Plant Closure Provisions Related Party Transactions [Abstract] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Schedule of Goodwill [Table Text Block] Summary of Goodwill Stock Issued During Period, Value, Treasury Stock Reissued Treasury stock reissued Gain (Loss) on Derivative Instruments, Net, Pretax, Total Gain (Loss) on Derivative Instruments, Net, Pretax Amount of gain/(loss) recognized in income European Metal Recycling Limited. European Metal Recycling Limited [Member] European Metal Recycling Limited [Member] Derivative liabilities. Derivatives Liabilities [Abstract] Derivatives (Level 1 measurement): 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 foreign currency exchange rate changes on cash Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Net income available to common stockholders Net income attributable to Innospec Accrued Income Taxes, Current Accrued income taxes Weighted Average Number of Shares Outstanding, Basic Basic Weighted average common shares outstanding Weighted Average Number of Shares Outstanding, Basic, Total Scenario [Axis] Scenario [Axis] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Segments [Axis] Segments [Axis] Amounts Reclassified Out Of Accumulated Other Comprehensive Income Loss [Abstract] Amounts Reclassified Out Of Accumulated Other Comprehensive Income Loss [Abstract] Related Party Transactions Disclosure [Text Block] Related Party Transactions APIC, Share-Based Payment Arrangement, Increase for Cost Recognition, Total APIC, Share-Based Payment Arrangement, Increase for Cost Recognition Stock option compensation Current portion of acquisition-related contingent consideration Business Combination, Contingent Consideration, Liability, Current Equity, Attributable to Parent Ending Balance Beginning Balance Total Innospec stockholders' equity Statement of Stockholders' Equity [Abstract] Type of Restructuring [Domain] Type of Restructuring [Domain] Treasury Stock [Member] Treasury Stock, Common [Member] Restructuring Reserve, Foreign Currency Translation Gain (Loss) Exchange effect Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Entity Address, Address Line Two Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Defined Benefit Pension Plan Items [Member] Noncontrolling Interest [Member] Non-Controlling Interest [Member] Other Assets, Current Other current assets Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] Roll-forward of Unrecognized Tax Benefits and Associated Accrued Interest and Penalties Derivative Instruments and Hedging Activities Disclosure [Abstract] Segment Reporting, CODM, Individual Title and Position or Group Name [Extensible Enumeration] 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] Product Technology [Member] Product technology. Product Technology [Member] Credit Facility [Axis] Credit Facility [Axis] Cost of Product and Service Sold Cost of goods sold Total cost of goods sold Total cost of goods sold Impairment, Long-Lived Asset, Held-for-Use Impairment, Long-Lived Asset, Held-for-Use, Total Impairment of property, plant and equipment Impairment of property, plant and equipment Number Of Workers Number of workers Treasury Stock, Value, Total Treasury Stock, Value Treasury stock (4,836,364 and 4,776,918 shares at cost, respectively) Related and Nonrelated Parties [Axis] Related Party [Axis] Pension Plan [Member] Pension Plan [Member] Foreign Exchange Contract [Member] Foreign Currency Forward Exchange Contracts [Member] Entity Address, City or Town Other Commitments [Axis] Other Commitments [Axis] Acquisition-related contingent consideration Business Combination, Contingent Consideration, Liability Business Combination, Contingent Consideration, Liability, Total Reclassified operating expenses Reclassified Operating Expenses Reclassified operating expenses. Number of Reportable Segments Number of reportable segments Security Exchange Name Credit Facility [Domain] Credit Facility [Domain] Europe [Member] Commitments Contingencies and Guarantees [Text Block] Contingencies Intangible Assets Disclosure [Text Block] Other Intangible Assets Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before income tax expense United Kingdom Plan. UK Plan [Member] United Kingdom Plan [Member] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested Options Forfeited, Number of Shares Number of shares, Forfeited Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Nonvested Options Forfeited, Weighted Average Grant Date Fair Value Weighted Average Grant-Date Fair Value, Forfeited Derivative Asset [Abstract] Derivatives (Level 1 measurement): Retirement Plan Sponsor Location [Axis] Retirement Plan Sponsor Location [Axis] Loss Contingency, Loss in Period Addtional charges incurred Inventory, Net Total inventories Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table] Measurement Basis [Axis] Statistical Measurement [Domain] Range [Domain] Assets, Current Total current assets Share-Based Payment Arrangement, Expense Compensation cost Document Period End Date Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Profit on disposal of property, plant and equipment Profit on disposal of property, plant and equipment Gain (Loss) on Disposition of Property Plant Equipment Gain (Loss) on Disposition of Property Plant Equipment, Total Statement of Financial Position [Abstract] Prepaid Expense Current Excluding Tax Prepaid Expense Current Excluding Tax Prepaid expenses Reclassification Out of Accumulated Other Comprehensive Income/(Loss) [Member] Reclassification out of Accumulated Other Comprehensive Income [Member] German plan. German Plan [Member] German Plan [Member] Not Designated as Hedging Instrument [Member] Not Designated as Hedging Instrument [Member] Liabilities Total liabilities Dividends Dividends, Total Dividend paid Defined Benefit Plan, Expected Return (Loss) on Plan Assets Expected return on plan assets Intangible asset capitalized Additions Finite-Lived Intangible Assets, Purchase Accounting Adjustments Finite-Lived Intangible Assets, Gross, Total Finite-Lived Intangible Assets, Gross Gross cost at January 1 Gross cost at September 30 Gross cost at March 31 Performance chemicals. Performance Chemicals [Member] Performance Chemicals [Member] Weighted Average Number of Shares Outstanding, Diluted Diluted Denominator for diluted earnings per share Entity File Number Securities Act File Number Fuel Specialties [Member] Fuel Specialties. Fuel Specialties [Member] Cover [Abstract] Increase (Decrease) in Accounts Payable and Accrued Liabilities Increase (Decrease) in Accounts Payable and Accrued Liabilities, Total Accounts payable and accrued liabilities Scenario [Domain] Liability, Defined Benefit Pension Plan, Noncurrent Post-employment obligations European businesses Segment Reporting Disclosure [Text Block] Segment Reporting Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Corporate, Non-Segment [Member] Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested, Number of Shares Number of shares, Vested Subsequent Event [Table] Other Net Income Expense [Member] Other Net Income Expense [Member] Other net income/(expense) [Member] Share-Based Compensation Arrangement by Share-Based Payment Award, Option, Nonvested, Weighted Average Exercise Price Weighted Average Grant-Date Fair Value, Ending balance Weighted Average Grant-Date Fair Value , Begining balance Increase (Decrease) in Restructuring Reserve Plant closure provisions Change in unrecognized tax benefits Unrecognized Tax Benefits, Period Increase (Decrease) Unrecognized Tax Benefits, Period Increase (Decrease), Total Restructuring Reserve, Noncurrent Due after one year Plant closure provisions, net of current portion Reported Value Measurement [Member] Carrying Amount [Member] Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense, Total Unrecognized tax benefits interest or penalties Operating Lease, Liability, Current Current portion of operating lease liabilities Depreciation, Depletion and Amortization, Total Depreciation, Depletion and Amortization Depreciation and amortization Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Amortization of prior service cost Document Transition Report Operating Expenses, Total Operating Expenses Total operating expenses Operating expenses Research and Development Expense, Total Research and Development Expense Research and development Payments for Repurchase of Common Stock Repurchase of common stock Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Total comprehensive income attributable to Innospec Liability, Defined Benefit Plan, Noncurrent, Total Liability, Defined Benefit Plan, Noncurrent Pension liabilities and post-employment benefits Statement of Cash Flows [Abstract] Amortization of prior service cost, net of tax Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, after Tax Amortization of prior service cost, net of tax of $(0.1) million, $0.0 million, $(0.1) million and $(0.1) million, respectively Share-Based Payment Arrangement, Option, Activity [Table Text Block] Summary of Transactions of Company's Stock Option Plans Business combinations, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Payments to Acquire Businesses, Net of Cash Acquired, Total Acquisition of the trade and net assets Finite-Lived Intangible Assets [Line Items] Earnings Per Share [Text Block] Earnings per Share Corporate costs. Corporate Costs Corporate costs Net income attributable to Innospec Inventory written-off Inventory Write-down Increase (Decrease) in Inventories, Total Increase (Decrease) in Inventories Inventories Accounting Changes and Error Corrections [Abstract] Amount of increase (decrease) to amortization of assets, excluding financial assets and goodwill, lacking physical substance with a finite life for foreign currency translation adjustments. Amortization Of Finite Lived Intangible Assets Translation Adjustments Exchange effect Schedule of Share-Based Compensation [Table Text Block] Schedule of share-based compensation. Summary of Transactions of the Company's Share Based Compensation Current Liability for Uncertainty in Income Taxes, Current Current Uncertain tax positions Other intangible assets Intangible Assets, Net (Excluding Goodwill) Net book amount at March 31 Net book amount at March 31 Assets [Abstract] Assets Restructuring and Related Activities [Abstract] Document Fiscal Year Focus Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Changes in Accumulated Other Comprehensive Loss Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Cash Flows from Investing Activities Retirement Benefits [Abstract] Accounts payable Accounts Payable, Current, Total Accounts Payable, Current Research and Development Expense [Member] Research and Development Expense [Member] Schedule of Net Benefit Costs [Table Text Block] Plan Net Pension Credit Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Amount due to related party Other Liabilities Other Liabilities, Total Fair Value Disclosures [Abstract] Commitments and Contingencies Disclosure [Abstract] Intangible Asset, Indefinite-Lived [Table] Stock Equivalent Units [Member] Stock Equivalent Units [Member] Stock Equivalent Units [Member] Derivative Instrument [Axis] Derivative Instrument [Axis] Defined Benefit Plan, Interest Cost Interest cost on projected benefit obligation Share-Based Payment Arrangement [Abstract] Cash Provided by (Used in) Investing Activity, Including Discontinued Operation Net cash used in investing activities Title of 12(b) Security Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivative Instruments and Risk Management Subsegments [Domain] Subsegments [Domain] Related and Nonrelated Parties [Domain] Related Party [Domain] Income Tax Disclosure [Text Block] Income Taxes Smith Gambrell And Russell Limited Liability Partnership [Member] Smith Gambrell And Russell Limited Liability Partnership [Member] Smith, Gambrell & Russell, LLP [Member] Other Liabilities, Noncurrent Other non-current liabilities Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Changes in assets and liabilities, net of effects of acquired and divested companies: Fees incured from Smith, Gambrell & Russell Accrued Professional Fees Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Fair Value, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Unrecognized Tax Benefits Opening balance at January 1 Unrecognized tax benefit Closing balance at September 30 Additional Paid-in Capital [Member] Additional Paid-In Capital [Member] Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Statement of Income Location, Balance [Axis] Income Statement Location [Axis] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Reclassification Adjustment out of Accumulated Other Comprehensive Income [Line Items] Trading Symbol Intangible Asset, Finite-Lived [Table] Related Party Transaction [Table] Schedule of Related Party Transactions, by Related Party [Table] Subsequent Event Type [Axis] Increase to the provisions for legacy operations Increase to the Provisions for Legacy Operations Increase to the provisions for legacy operations. Schedule of Finite-Lived Intangible Assets [Table Text Block] Summary of Other Intangible Assets Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Cash Flows from Financing Activities Fair Value, Recurring [Member] Recurring [Member] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Summary of Transactions of the Share Based Compensation Plans Share-Based Payment Arrangement, Activity [Table Text Block] Goodwill and Intangible Assets Disclosure [Abstract] Maximum percentage of stock options granted Maximum Percentage of Stock Options Granted Maximum Percentage of Stock Options Granted Proceeds from Noncontrolling Interests Non-controlling interest Business Combination [Axis] Other fuel specialties. Other Fuel Specialties [Member] Other [Member] Statement of Comprehensive Income [Abstract] Other comprehensive income/(loss): Maximum [Member] Maximum [Member] Impairment of Intangible Assets (Excluding Goodwill) Impairment of Intangible Assets (Excluding Goodwill), Total Impairment The amount of impaired assets totaled Impairment Advan Six. Advan Six [Member] Advan Six [Member] Statistical Measurement [Axis] Range [Axis] Finite-Lived Intangible Assets, Accumulated Amortization Accumulated amortization at January 1 Accumulated amortization at March 31 Accumulated amortization at March 31 Accumulated amortization at January 1 Receivables, Net, Current, Total Receivables, Net, Current Trade and other accounts receivable (less allowances of $14.2 million and $11.8 million respectively) Trade and other accounts receivable (less allowances of $14.2 million and $11.8 million respectively) Common Stock, Value, Issued Common stock, $0.01 par value, authorized 40,000,000 shares, issued 29,554,500 shares Due date of revolving credit Line of Credit Facility, Expiration Date Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Summary of Reclassifications Out of Accumulated Other Comprehensive Loss Beginning Balance Equity, Including Portion Attributable to Noncontrolling Interest Ending Balance Total equity Related Party Transaction, Amounts of Transaction Tendering process to select best buyer of scrap metal Defined Benefit Plan Service Credit Cost Defined Benefit Plan Service Credit Cost Service credit/(cost) Service credit/(cost) Proceeds from Sale of Treasury Stock Issue of treasury stock Disclosure of Reclassification Amount [Text Block] Reclassifications out of Accumulated Other Comprehensive Loss Biotechnology Solutions LLC [Member] Biotechnology Solutions LLC. Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Entity Registrant Name Debt Disclosure [Text Block] Long-Term Debt Other Nonoperating Income (Expense), Total Other Nonoperating Income (Expense) Other income/(expense), net Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Subsequent Events [Abstract] Income Tax Expense (Benefit), Total Income Tax Expense (Benefit) Income tax expense Measurement Frequency [Axis] Measurement Frequency [Axis] Common Stock, Dividends, Per Share, Cash Paid Dividend paid, per share Summary of Segment Reporting related to Cost of Goods Sold Schedule of Segment Reporting Information Relates to Cost Of Goods Sold, by Segment [Table Text Block] Schedule of segment reporting information relates to cost of goods sold, by segment. 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 Accumulated Other Comprehensive Income (Loss), Net of Tax, Total Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Consolidation Items [Axis] Consolidation Items [Axis] Payments for Restructuring Utilized in the period Assets Total assets Income Statement [Abstract] Retirement Plan Name [Domain] Retirement Plan Name [Domain] Restructuring Cost [Table] Schedule of Restructuring and Related Costs [Table] Defined Benefit Plan, Amortization of Gain (Loss) Amortization of actuarial net losses Amortization of actuarial net gains Selling, General and Administrative Expenses [Member] Selling, General and Administrative Expenses [Member] Earnings Per Share, Diluted, Total Earnings Per Share, Diluted Diluted Earnings per share, diluted: Segment Reporting Schedule of Segment Reporting Information, by Segment [Table Text Block] Operating Segments [Member] Operating Segments [Member] City Area Code Other Comprehensive Income (Loss), Net of Tax Total other comprehensive income/(loss) Line of credit facility cumulative drawn down. Line Of Credit Facility Cumulative Drawn Down Line of credit facility cumulative drawn down Line of credit facility, maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Defined Benefit Plan [Table] Schedule of Defined Benefit Plans Disclosures [Table] Non-cash movements on defined benefit pension plans. Non Cash Movements On Defined Benefit Pension Plans Non-cash movements on defined benefit pension plans Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Computer Software, Intangible Asset [Member] Software Development [Member] Retirement Plan Name [Axis] Retirement Plan Name [Axis] Derivative Liability, Subject to Master Netting Arrangement, before Offset Foreign currency forward exchange contracts Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, Tax Amortization of actuarial net losses, tax Property, Plant and Equipment, Net, Total Property, Plant and Equipment, Net Net property, plant and equipment Impairment of intangible assets Impairment of Intangible Assets, Finite-Lived Impairment of intangible assets Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations, Total Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Including Discontinued Operation Cash and cash equivalents at end of period Cash and cash equivalents at beginning of period Operating income Operating Income (Loss) Operating income Operating income/(loss) Goodwill, Foreign Currency Translation, Gain (Loss) Goodwill, foreign currency translation gain (loss) Exchange effects Exchange effects Retained Earnings [Member] Retained Earnings [Member] Share-Based Payment Arrangement, Noncash Expense, Total Share-Based Payment Arrangement, Noncash Expense Stock option compensation Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax, Total Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Changes in cumulative translation adjustment, tax Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, Tax Amortization of prior service credit, tax Operating Lease, Liability, Noncurrent Operating lease liabilities, net of current portion Fair Value, Inputs, Level 1 [Member] Quoted Prices in Active Markets for Identical Assets (Level 1) [Member] Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Net cash used in financing activities Deferred Income Tax Liabilities, Net Deferred tax liabilities Emission Trading Scheme Credits [Member] Emission Trading Scheme Credits [Member] Derivative Contract [Domain] Derivative Contract [Domain] Goodwill [Table] Schedule of Goodwill [Table] Exchange effect Finite-Lived Intangible Assets, Foreign Currency Translation Gain (Loss) Entity Interactive Data Current Defined Benefit Plan, Plan Assets, Category [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Statement of Income Location, Balance [Domain] Income Statement Location [Domain] Fair Value Measurement [Domain] Changes in cumulative translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax, Total Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Cash Flows from Operating Activities Repayment on credit facility Repayments of Lines of Credit Repayments of revolving credit facility Accounting Standards Update and Change in Accounting Principle [Text Block] Recently Issued Accounting Pronouncements Entity Tax Identification Number Prepaid Taxes Prepaid income taxes Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Basis of Presentation Local Phone Number Accumulated Other Comprehensive Income (Loss) [Line Items] Share-Based Payment Arrangement, Nonvested Award, Option, Cost Not yet Recognized, Amount Total compensation cost related to non-vested stock options not yet recognized Weighted Average Number of Shares Outstanding, Diluted [Abstract] Weighted average shares outstanding (in thousands): Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Amortization of actuarial net losses, net of tax Amortization of actuarial net losses/(gains), net of tax of $0.2 million, $0.0 million, $0.4 million and $0.0 million, respectively Pension Deed [Member] Deed of alteration and agreement (Pension deed) Pension Deed [Member] Increase decrease in unrecognized tax benefits. Increase Decrease In Unrecognized Tax Benefits Unrecognized tax benefits Weighted Average Number of Shares Outstanding, Basic [Abstract] Denominator (in thousands): Payments for Capital Improvements Capital expenditures Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Other comprehensive income/(loss) before reclassifications Revenue from Contract with Customer, Excluding Assessed Tax Net sales Non-derivatives assets. Non Derivatives Assets [Abstract] Non-derivatives: Net Income (Loss) Attributable to Parent [Abstract] Numerator (in millions): Inventory, Net [Abstract] Inventories (less allowances of $39.4 million and $40.4 million respectively): Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Expected compensation cost recognized over the weighted-average period Acquisition related impact of foreign exchange Acquisition Related Impact Of Foreign Exchange Acquisition related impact of foreign exchange. Entity Emerging Growth Company President and chief executive officer. President And Chief Executive Officer [Member]