75000 - Document - Document and Entity Information link:presentationLink link:calculationLink link:definitionLink 75010 - Statement - STATEMENTS OF NET ASSETS AVAILABLE FOR BENEFITS link:presentationLink link:calculationLink link:definitionLink 75020 - Statement - STATEMENT OF CHANGES IN NET ASSETS AVAILABLE FOR BENEFITS link:presentationLink link:calculationLink link:definitionLink 75030 - Disclosure - Description of the Plan link:presentationLink link:calculationLink link:definitionLink 75040 - Disclosure - Significant Accounting Policies link:presentationLink link:calculationLink link:definitionLink 75050 - Disclosure - Master Trust Investments link:presentationLink link:calculationLink link:definitionLink 75060 - Disclosure - Investment Contracts link:presentationLink link:calculationLink link:definitionLink 75070 - Disclosure - Fair Value Measurements link:presentationLink link:calculationLink link:definitionLink 75080 - Disclosure - Transactions with Related Parties link:presentationLink link:calculationLink link:definitionLink 75090 - Disclosure - Tax Status of the Plan link:presentationLink link:calculationLink link:definitionLink 75100 - Disclosure - Risks and Uncertainties link:presentationLink link:calculationLink link:definitionLink 75110 - Disclosure - Schedule of Assets (Held at End of Year) link:presentationLink link:calculationLink link:definitionLink 75120 - Disclosure - Significant Accounting Policies (Policies) link:presentationLink link:calculationLink link:definitionLink 75130 - Disclosure - Master Trust Investments (Tables) link:presentationLink link:calculationLink link:definitionLink 75140 - Disclosure - Fair Value Measurements (Tables) link:presentationLink link:calculationLink link:definitionLink 75150 - Disclosure - Schedule of Assets (Held at End of Year) (Tables) link:presentationLink link:calculationLink link:definitionLink 75160 - Disclosure - Description of the Plan - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75170 - Disclosure - Master Trust Investments - Summary of Net Assets, Including Investments, Receivables, and Liabilities, of Master Trust and Plan's Interest in Net Assets of Master Trust (Details) link:presentationLink link:calculationLink link:definitionLink 75180 - Disclosure - Master Trust Investments - Summary of Net Appreciation in Investments and Investment Income (Expense) in Master Trust (Details) link:presentationLink link:calculationLink link:definitionLink 75190 - Disclosure - Investment Contracts - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75200 - Disclosure - Fair Value Measurements - Summary of Fair Value Hierarchy Master Trust Investment Assets at Fair Value (Details) link:presentationLink link:calculationLink link:definitionLink 75210 - Disclosure - Fair Value Measurements - Summary of Fair Value Hierarchy Master Trust Investment Assets at NAV (Details) link:presentationLink link:calculationLink link:definitionLink 75220 - Disclosure - Transactions with Related Parties - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75230 - Disclosure - Tax Status of the Plan - Additional Information (Details) link:presentationLink link:calculationLink link:definitionLink 75240 - Disclosure - Schedule of Assets (Held at End of Year) - Schedule of Assets (Held at End of Year) (Details) link:presentationLink link:calculationLink link:definitionLink EBP, Change in Net Asset Available for Benefit, Increase [Abstract] Additions to net assets attributed to: EBP, Change in Net Asset Available for Benefit, Decrease from Payment to Participant Benefits paid to participants EBP, Receivable [Abstract] Receivables: Level 2 Fair Value, Inputs, Level 2 [Member] EBP, Related Party and Party-in-Interest Transactions [Line Items] Document Fiscal Period Focus EBP, Employer Contribution, Receivable Employer contributions EBP, Master Trust [Line Items] EBP, Investment, Contract Value EBP, Investment, Contract Value, Total Investments, at contract value EBP, Fully Benefit-Responsive Investment Contract [Table] EBP, Tax Status [Abstract] Employee Benefit Plan Change In Net Asset Available For Benefit Increase From Income On Investment Employee benefit plan change in net asset available for benefit increase from income on investment. Plan interest in Ashland Inc Savings Plan Master Trust investment income EBP, Description of Plan [Text Block] Description of the Plan EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Note Receivable from Participant Loan interest EBP, Change in Net Asset Available for Benefit, Decrease from Administrative Expense Administrative expenses Fees paid for investment management EBP, Description of Plan [Line Items] EBP, Master Trust [Abstract] Employee Benefit Plan Schedule of Asset Held for Investment [Text Block] Employee benefit plan schedule of asset held for investment. Schedule of Assets (Held at End of Year) EBP, Employer Contribution, Matching Percentage Employee benefit plan, employer contribution of eligible pay, matching percentage EBP, Investment, Fair Value and NAV [Abstract] Liabilities EBP, Liability [Abstract] EBP, Accounting Policy [Line Items] EBP, Change in Net Asset Available for Benefit, Transfer to (from) Plan Plan transfers EBP, Master Trust [Table] EBP, Schedule of Asset Held for Investment [Table] Employee Benefit Plan Notes Receivable from Promissory Notes from Participants Loan to Purchase Principal Term Employee benefit plan notes receivable from promissory notes from participants loan to purchase principal term. Employee benefit plan notes receivable from promissory notes from participants loan to purchase principal term EBP, Statement of Net Asset Available for Benefit [Line Items] EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment [Abstract] Investment income: EBP, Note Receivable from Participant, Account, Maximum Borrowing, Amount Employee benefit plan maximum loan amount Employee Benefit Plan, Note Receivable from Participant, Account, distributed Employee Benefit Plan, Note Receivable from Participant, Account, distributed. Employee benefit plan, note receivable from participant, account distributed Employee benefit plan employer contribution earning percentage. Employee Benefit Plan, Employer Contribution, Earning Percentage Employee benefit plan, employer contribution, earning percentage Common/Collective Trusts Common Collective Trust [Member] Amendment Flag EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash EBP, Change in Net Asset Available for Benefit, Increase from Employer Contribution, Cash and Noncash, Total Employers EBP, Change in Net Asset Available for Benefit, Decrease [Abstract] Deductions from net assets attributed to: EBP, Note Receivable from Participant, Account, Minimum Borrowing, Amount Employee benefit plan minimum loan amount EBP, Payment to Participant [Policy Text Block] Payment of Benefits Master Trust EBP, Master Trust [Policy Text Block] Stable Value Fund Money Market Fund [Member] Stable Value Fund Money Market Fund. Stable Value Fund Money Market Fund EBP, Participant Contribution, Receivable Participant contributions EBP, Schedule of Asset Held for Investment [Line Items] Fair Value Hierarchy and NAV [Axis] EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Domain] Investment Type [Axis] Investments, at fair value EBP, Investment, Fair Value EBP, Investment, Fair Value, Total Fair value Document Type Entity Central Index Key Investments EBP, Investment [Policy Text Block] Employee Benefit Plan Notes Receivable From Participants Loan to Purchase Principal Residence Term Employee benefit plan notes receivable from participants loan to purchase principal residence term. Employee benefit plan, residential notes receivable from participants loan term EBP, Accounting Policy [Table] EBP, Basis of Accounting [Policy Text Block] Basis of Presentation Current Fiscal Year End Date EBP, Investment, Plan Interest in Master Trust, Fair Value Investments at fair value EBP, Description of Plan [Table] EBP, Employer, Common Stock [Member] Ashland Inc. Common Stock EBP, Change in Net Asset Available for Benefit, Increase from Interest and Dividend Income on Investment Total Investment income EBP, Schedule of Allocation, Asset and Liability [Table Text Block] Summary of Net Assets, Including Investments, Receivables, and Liabilities, of Master Trust and Plan's Interest in Net Assets of Master Trust Net Master Trust assets EBP, Investment, Fair and Contract Value EBP, Investment, Number of Shares Shares (in shares) Minimum [Member] Minimum EBP, Related Party and Party-in-Interest Transactions [Text Block] Transactions with Related Parties EBP, Change in Net Asset Available for Benefit, Increase Total additions Fair Value, Inputs, Level 3 [Member] Level 3 EBP, Expense [Policy Text Block] Administrative Expenses Document Information [Line Items] EBP, Accrued Expense Accrued expenses Fair Value Measured at Net Asset Value Per Share [Member] Fair Value Measured at Net Asset Value Per Share EBP, Statement of Net Asset Available for Benefit [Abstract] Participants EBP, Change in Net Asset Available for Benefit, Increase from Participant Contribution, Excluding Rollover EBP, Change in Net Asset Available for Benefit, Increase from Contribution [Abstract] Contributions: Determination letter date EBP, Tax Determination Letter, Date EBP, Liability Total liabilities EBP, Tax Qualification Status [Extensible Enumeration] Tax qualification status EBP, Related Party and Party-in-Interest Transactions [Abstract] EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value, Ending Balance EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value, Beginning Balance EBP, Investment, Excluding Plan Interest in Master Trust, Fair Value, Total Investments at fair value Fair Value EBP, Use of Estimate [Policy Text Block] Use of Estimates Mutual Fund [Member] Shares of Registered Investment Companies Entity [Domain] EBP, Summary of Accounting Policy [Text Block] Significant Accounting Policies Employee Benefit Plan Participant Loan Maturity Period Employee benefit plan participant loan maturity period. Employee benefit plan, participant loans, maturity period EBP, Management [Member] Investment Management EBP, Investment, Fair Value and NAV [Text Block] Fair Value Measurements EBP, Description of Plan and Accounting Change [Abstract] EBP, Asset Held for Investment, Participant Loan, after Deemed Distribution Employee benefit plan, participant loans, current value EBP, Statement of Change in Net Asset Available for Benefit [Line Items] EBP, Investment, Plan Interest in Master Trust, Fair and Contract Value [Abstract] Interest in the Ashland Inc Savings Plan Master Trust: Statistical Measurement [Domain] EBP, Note Receivable from Participant Notes receivable from participants Document Period End Date EBP, Risk and Uncertainty [Table] Fair Value Hierarchy and NAV [Domain] Employee Benefit Plan, Investment Contracts [Policy Text Block] Employee Benefit Plan, Investment Contracts. Investment Contracts EBP, Note Receivable from Participant, Account, Maximum Borrowing, to Total Account, Percentage Employee benefit plan maximum borrowing percentage EBP, Tax Determination Letter, Obtained [true false] Determination letter obtained EBP, Related Party and Party-in-Interest Transactions [Table] EBP, Change in Net Asset Available for Benefit, Increase from Interest Income on Investment Interest EBP, Participant Contribution, Pretax, Maximum Annual Compensation, Amount Employee benefit plan, participant contribution Cover [Abstract] Investments [Domain] EBP, Risk and Uncertainty [Abstract] EBP, Master Trust [Text Block] Master Trust Investments Redemption Notice Period EBP, Fair Value, Investment, NAV, Redemption, Notice Period EBP, Net Asset Available for Benefit Net assets available for benefits, end of year Net assets available for benefits, beginning of year Net assets available for benefits EBP, Investment, Fair Value and NAV [Table Text Block] Summary of Fair Value Hierarchy Master Trust Investment Assets at Fair Value and NAV EBP, Schedule of Asset Held for Investment [Abstract] EBP, Schedule of Asset Held for Investment [Table Text Block] Schedule of Assets (Held at End of Year) EBP, Fully Benefit-Responsive Investment Contract [Abstract] EBP, Statement of Net Asset Available for Benefit [Table] Document Fiscal Year Focus Investment Excluding Common Collective Trust [Member] Investment excluding common collective trust. Investment Excluding Common Collective Trust EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Gain (Loss) on Investment, Total Net realized and unrealized appreciation in fair value of investments EBP, Nonconsolidated, Master Trust [Member] Master Trust Balances EBP, Fair Value, Investment, NAV, Unfunded Commitment Unfunded Commitments EBP020 [Member] EBP 020 EBP 020. EBP, Statement of Change in Net Asset Available for Benefit [Table] EBP, Asset Total assets EBP, Participant Contribution, Pretax, Maximum Annual Compensation to Total Compensation, Percentage Employee benefit plan, participant contribution percentage Money Market Funds [Member] Money Market Fund EBP, Fully Benefit-Responsive Investment Contract [Line Items] EBP, Plan Number Employee benefit plan, plan number EBP, Nonconsolidated, Plan Interest in Master Trust [Member] Plan's Interest in Master Trust Balances EBP, Investment, Fair Value and NAV [Line Items] Document Information [Table] Legal Entity [Axis] EBP, Risk and Uncertainty [Line Items] Employee Benefit Plan, Fair Value, Investment, Net Asset Value Redemption Frequency Employee benefit plan, fair value, investment, net asset value redemption frequency. Redemption Frequency EBP, Asset [Abstract] Assets EBP, Change in Net Asset Available for Benefit, Increase (Decrease) from Income (Loss) on Investment Total EBP, Synthetic Investment Contract [Member] Synthetic GIC Contracts EBP, Investment, Fair Value and NAV [Table] EBP, Accounting Policy, Accounting Standard Update, and Change in Accounting Principle [Abstract] Investment Contracts [Text Block] Investment contracts. Investment Contracts EBP, Tax Status [Text Block] Tax Status of the Plan EBP, Nonconsolidated, Master Trust and Plan Interest in Master Trust [Axis] Maximum [Member] Maximum Statistical Measurement [Axis] EBP, Statement of Change in Net Asset Available for Benefit [Abstract] EBP, Fair Value, Investment, NAV, Redemption Other Restriction, Description Other Redemption Restrictions Dividends EBP, Change in Net Asset Available for Benefit, Increase from Dividend Income on Investment Entity Registrant Name EBP, Schedule of Allocation, Income and Change in Plan Equity [Table Text Block] Summary of Net Appreciation in Investments and Investment Income (Expense) in Master Trust Employee benefit plan, interest rate EBP, Asset Held for Investment, Participant Loan, Interest Rate Employee benefit plan, participant loans, interest rate EBP, Related Party and Party-in-Interest [Domain] EBP, Related Party and Party-in-Interest [Axis] EBP, Risk and Uncertainty [Text Block] Risks and Uncertainties Income and Expense Recognition Employee Benefit Plan, Income and Expense Recognition [Policy Text Block] Employee Benefit Plan, Income and Expense Recognition. EBP, Change in Net Asset Available for Benefit, Decrease Total deductions EBP, Investment, Plan Interest in Master Trust, Contract Value Investment contracts at contract value Level 1 Fair Value, Inputs, Level 1 [Member] EBP, Tax Status [Line Items] Entity Tax Identification Number Employee benefit plan, employer identification number Net change in plan assets EBP, Change in Net Asset Available for Benefit, Increase (Decrease) EBP, Tax Status [Table] Investments at contract value EBP, Investment, Excluding Plan Interest in Master Trust, Contract Value Employee benefit plan, catch up contribution Employee benefit plan, maximum annual catch up contribution amount Employee benefit plan, maximum annual catch up contribution amount.