Statistical Measurement [Domain] Statistical Measurement [Domain] Related Parties and Parties-In-Interest Transactions EBP, Related Party and Party-in-Interest Transactions [Text Block] Interest income on notes receivable from participants EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Document Information [Line Items] Document Information [Line Items] Distributions and sales EBP, Investment, Sold, Number of Shares Participant notes receivable, maximum borrowing amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] EBP Vesting Tranche [Axis] EBP Vesting Tranche [Axis] EBP Vesting Tranche Employee contributions EBP, Participant Contribution, Receivable EBP, Description of Plan and Accounting Change [Abstract] Matching contributions, cost EBP, Asset Held For Investment, Cost EBP, Asset Held For Investment, Cost Investment Type [Axis] Investment Type [Axis] Participant notes receivable, maximum borrowing amount, vested amount EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Appreciation (Depreciation) EBP, Investment, Excluding Plan Interest In Master Trust, Appreciation (Depreciation) EBP, Investment, Excluding Plan Interest In Master Trust, Appreciation (Depreciation) Balance, beginning of period Balance, end of period Number of shares EBP, Investment, Number of Shares After tax contribution, maximum EBP, Participant Contribution, After Tax, Maximum Contribution To Total Compensation, Percentage EBP, Participant Contribution, After Tax, Maximum Contribution To Total Compensation, Percentage Tax Status EBP, Tax Status [Text Block] EBP, Liability EBP, Liability EBP, Description of Plan [Line Items] EBP, Description of Plan [Line Items] Investment income—interest and dividends EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment Schedule of Activity in the NewMarket Common Stock Fund EBP, Related Party and Party-in-Interest Transactions [Table Text Block] EBP Vesting Tranche Four EBP Vesting Tranche Four [Member] EBP Vesting Tranche Four EBP, Schedule of Asset Held for Investment [Table] EBP, Schedule of Asset Held for Investment [Table] Notes receivable from participants, current value EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Fair Value Measurements EBP, Investment, Fair Value and NAV [Text Block] Participant contribution, vesting percentage EBP, Participant Contribution, Vesting Percentage EBP, Participant Contribution, Vesting Percentage Notes receivable from participants, cost EBP, Asset Held for Investment, Participant Loan, Cost EBP, Asset Held for Investment, Participant Loan, Cost EBP, Investment, Fair Value and NAV [Table] EBP, Investment, Fair Value and NAV [Table] Employer EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Noncash Due from trustee EBP, Due From Trustee EBP, Due From Trustee Total contributions EBP, Change in Net Asset Available for Benefit, Increase from Contribution Maximum amount of base pay EBP, Participant Contribution, Maximum Annual Compensation To Total Compensation, Percentage EBP, Participant Contribution, Maximum Annual Compensation To Total Compensation, Percentage Participant notes receivable, minimum borrowing amount EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Money market fund Money Market Funds [Member] EBP Vesting Tranche Three EBP Vesting Tranche Three [Member] EBP Vesting Tranche Three EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Related Party and Party-in-Interest Transactions [Table] Benefit payments EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Employer contributions EBP, Employer Contribution, Receivable Common stock, par value EBP, Investment, Par or Maturity Value EBP, Net Asset Available for Benefit At beginning of year At end of year EBP, Net Asset Available for Benefit Employer contribution, vesting, years of service EBP, Employer Contribution, Vesting, Years Of Service EBP, Employer Contribution, Vesting, Years Of Service EBP, Schedule of Asset Held for Investment [Line Items] EBP, Schedule of Asset Held for Investment [Line Items] EBP, Accounting Policy [Line Items] EBP, Accounting Policy [Line Items] EBP, Asset EBP, Asset EBP Vesting Tranche [Domain] EBP Vesting Tranche [Domain] EBP Vesting Tranche [Domain] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] EBP, Tax Status [Abstract] Net increase EBP, Change in Net Asset Available for Benefit, Increase (Decrease) Cover [Abstract] EBP, Other Related Party and Party-in-Interest EBP, Other Related Party and Party-in-Interest [Member] Maximum Maximum [Member] EBP, Asset [Abstract] EBP, Asset [Abstract] Pre-tax contributions and Roth contributions, maximum EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage Minimum Minimum [Member] Mergers and Transfers EBP, Change In Net Asset Available For Benefit, Mergers And Transfers [Abstract] EBP, Change In Net Asset Available For Benefit, Mergers And Transfers EBP, Schedule of Asset Held for Investment [Abstract] Net increase before mergers and transfers EBP, Change In Net Asset Available For Benefit Before Mergers And Transfers EBP, Change In Net Asset Available For Benefit Before Mergers And Transfers Entity [Domain] Entity [Domain] Current value of investments and participant loans EBP, Asset Held for Investment Investment, Identifier [Axis] Investment, Identifier [Axis] Number of money market fund Number Of Money Market Fund Number Of Money Market Fund Transfer from American Pacific Corporation 401(k) Plan EBP, Change In Net Asset Available For Benefit, Increase From Merger EBP, Change In Net Asset Available For Benefit, Increase From Merger Total transfers Assets transferred into the plan EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan EBP, Investment, Fair Value and NAV [Abstract] Purchases EBP, Investment, Excluding Plan Interest In Master Trust, Purchased, Amount EBP, Investment, Excluding Plan Interest In Master Trust, Purchased, Amount Employer matching percentage EBP, Employer Contribution, Matching Percentage Basis of Accounting EBP, Basis of Accounting [Policy Text Block] EBP, Subsequent Event [Line Items] EBP, Subsequent Event [Line Items] Amount EBP, Investment, Fair Value [Abstract] Risks and Uncertainties EBP, Risk and Uncertainty [Policy Text Block] EBP, Tax Status [Line Items] EBP, Tax Status [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Statement of Change in Net Asset Available for Benefit [Table] Mutual funds Mutual Fund [Member] EBP, Description of Plan [Table] EBP, Description of Plan [Table] Number of common stock funds prohibiting new investments Number Of Common Stock Funds Prohibiting New Investments Number Of Common Stock Funds Prohibiting New Investments Investment Valuation and Income Recognition EBP, Investment [Policy Text Block] Interest and dividends EBP, Investment Income, Receivable Amendment Flag Amendment Flag Employer contribution, vesting percentage EBP, Employer Contribution, Vesting Percentage EBP, Employer Contribution, Vesting Percentage EBP Vesting Tranche Two EBP Vesting Tranche Two [Member] EBP Vesting Tranche Two Pre-tax contributions and Roth contributions, minimum EBP, Participation Contribution, Pretax, Minimum Annual Compensation to Total Compensation, Percentages EBP, Participation Contribution, Pretax, Minimum Annual Compensation to Total Compensation, Percentages Schedule of Fair Value Measurements EBP, Investment, Fair Value and NAV [Table Text Block] Total deductions EBP, Change in Net Asset Available for Benefit, Decrease Current value EBP, Asset Held for Investment, Investment, Excluding Plan Interest in Master Trust, Current Value Plan Termination EBP, Plan Termination [Text Block] EBP, Statement of Change in Net Asset Available for Benefit [Abstract] EBP, Subsequent Event [Table] EBP, Subsequent Event [Table] EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Related Party and Party-in-Interest Transactions [Line Items] EBP, Related Party and Party-in-Interest Transactions [Line Items] Contributions EBP, Contribution [Abstract] Forfeitures during the plan year EBP, Forfeited Nonvested Account, Decrease from Employer Contribution EBP, Statement of Net Asset Available for Benefit [Abstract] EBP Vesting Tranche One EBP Vesting Tranche One [Member] EBP Vesting Tranche One EBP 002 EBP 002 [Member] EBP 002 Description of Plan EBP, Description of Plan [Text Block] Summary of Significant Accounting Policies EBP, Summary of Accounting Policy [Text Block] Employees EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution Document Period End Date Document Period End Date Total additions EBP, Change in Net Asset Available for Benefit, Increase EBP, Related Party And Party-In-Interest Transaction [Roll Forward] EBP, Related Party And Party-In-Interest Transaction [Roll Forward] EBP, Related Party And Party-In-Interest Transaction EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Statement of Net Asset Available for Benefit [Line Items] Entity Central Index Key Entity Central Index Key Notes receivable from participants, interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate After tax contributions, minimum EBP, Participant Contribution, After Tax, Minimum Contribution To Total Compensation, Percentage EBP, Participant Contribution, After Tax, Minimum Contribution To Total Compensation, Percentage Investments, at fair value (Note 3) Investments, at fair value Balance, beginning of period Balance, end of period EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value Legal Entity [Axis] Legal Entity [Axis] Entity tax identification number Entity Tax Identification Number Net changes in investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Plan number EBP, Plan Number Document Type Document Type Level 3 Fair Value, Inputs, Level 3 [Member] EBP, Statement of Net Asset Available for Benefit [Table] EBP, Statement of Net Asset Available for Benefit [Table] Participant notes receivable maximum borrowing term EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term EBP, Note Receivable From Participant, General Loan, Maximum Borrowing Term EBP, Investment, Fair Value and NAV [Line Items] EBP, Investment, Fair Value and NAV [Line Items] Accounting Estimates EBP, Use of Estimate [Policy Text Block] Shares EBP, Investment, Number Of Shares [Abstract] EBP, Investment, Number Of Shares Purchases EBP, Investment, Purchased, Number of Shares Number of mutual funds Number Of Mutual Funds Number Of Mutual Funds Statistical Measurement [Axis] Statistical Measurement [Axis] Deductions from net assets attributed to EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Notes receivable from participants EBP, Note Receivable from Participant Level 2 Fair Value, Inputs, Level 2 [Member] EBP, Related Party and Party-in-Interest [Axis] EBP, Related Party and Party-in-Interest [Axis] Schedule H, Line 4i – Schedule of Assets (Held At End of Year) EBP, Schedule of Asset Held for Investment [Table Text Block] EBP, Related Party and Party-in-Interest [Domain] EBP, Related Party and Party-in-Interest [Domain] Net appreciation in fair value of investments EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment Cash (Note 3) Cash EBP, Noninterest-Bearing Cash EBP, Accounting Policy [Table] EBP, Accounting Policy [Table] Investments [Domain] Investments [Domain] EBP, Subsequent Event [Abstract] Document Information [Table] Document Information [Table] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Due To Trustee EBP, Due To Trustee EBP, Due To Trustee Level 1 Fair Value, Inputs, Level 1 [Member] Entity Registrant Name Entity Registrant Name Distributions and sales EBP, Investment, Excluding Plan Interest In Master Trust, Sold Amount EBP, Investment, Excluding Plan Interest In Master Trust, Sold Amount Subsequent Events EBP, Subsequent Event [Text Block] Additions to (deductions from) net assets attributed to EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment [Abstract] Common stocks Common Stock [Member] EBP, Tax Status [Table] EBP, Tax Status [Table] EBP, Liability [Abstract] EBP, Liability [Abstract] Receivables EBP, Receivable [Abstract] Fair Value Fair Value, Inputs, Level 1, Level 2, and Level 3 [Member] EBP, Receivable EBP, Receivable Employer contribution, percentage of participation contribution matched EBP, Employer Contribution, Participant Compensation Matched, Percentage