2031 and 2032 Senior Secured Notes 2031 and 2032 Senior Secured Notes [Member] 2031 and 2032 Senior Secured Notes Schedule of Net Unfunded AFFA Liability, Net of Tax Schedule of Rollforward of Net Unfunded Amended and Restated Final Funding Agreement Liability [Table Text Block] Schedule of Rollforward of Net Unfunded Amended and Restated Final Funding Agreement Liability [Table Text Block] Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Foreign tax credit carry-forwards, subject to expiration Deferred Tax Assets, Tax Credit Carryforwards, Foreign, Subject to Expiration Deferred Tax Assets, Tax Credit Carryforwards, Foreign, Subject to Expiration Term Loan due 2028 Term Loan Term Loan Due 2028 [Member] Term Loan Due 2028 Award Timing Predetermined Award Timing Predetermined [Flag] Indefinite-lived Intangible Assets [Axis] Indefinite-Lived Intangible Assets [Axis] Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] Effect of foreign exchange on Asbestos net liabilities Asbestos Adjustment Gain Loss On Foreign Exchange Gain (loss) on foreign exchange movements in the other asbestos related assets and liabilities which are denominated in Australian dollars. August 2024 Grant August 2024 Grant [Member] August 2024 Grant Tabular List, Table Tabular List [Table Text Block] Accounting Pronouncements New Accounting Pronouncements, Policy [Policy Text Block] Non-cash ROU assets obtained in exchange for new lease liabilities Right-Of-Use Asset Obtained In Exchange For Lease Liability Right-Of-Use Asset Obtained In Exchange For Lease Liability Finance leases: Finance Lease, Liability [Abstract] Schedule of Contributions to AICF Schedule of Contributions to AICF [Table Text Block] Schedule of Contributions to AICF Consideration transferred, liabilities incurred Business Combination, Consideration Transferred, Liabilities Incurred Adjustment to Compensation: Adjustment to Compensation [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Movement in income tax payable Amount Of Deferred Tax Assets Applied To Income Tax Payable Portion of deferred income tax asset that becomes available to the Company as an Australian tax deduction resulting from the Company's previous contributions to AICF. Revenues Revenue from Contract with Customer [Text Block] Schedule of Indefinite-Lived Intangible Assets [Table] Intangible Asset, Indefinite-Lived [Table] Deferred income taxes - Asbestos Deferred Tax Assets Net Asbestos Deferred Tax Assets Net Asbestos Schedule of Reconciliation of Cash and Cash Equivalents - Asbestos Schedule of Cash and Cash Equivalents [Table Text Block] General Corporate and R&D Corporate And Reconciling Items [Member] Corporate And Reconciling Items Current income tax expense Current Income Tax Expense (Benefit) Asbestos Injuries Compensation Fund Asbestos Injuries Compensation Fund [Member] Asbestos injuries compensation fund. 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Term A-2 Facility, due 2030 Secured Debt A-2 [Member] Secured Debt A-2 Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Proceeds from sale of property, plant and equipment Proceeds from Sale of Property, Plant, and Equipment Proceeds from term loans Proceeds from Issuance of Debt Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Schedule of Income Taxes Paid (Net of Refunds) by Jurisdiction Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, after Tax Estimated fair value of the assumed equity awards, recognized as goodwill Share-Based Compensation Arrangement By Share-Based Payment Award, Fair Value Of Awards Assumed In Business Combination Recognized As Goodwill Share-Based Compensation Arrangement By Share-Based Payment Award, Fair Value Of Awards Assumed In Business Combination Recognized As Goodwill Senior Secured Notes Senior Secured Notes [Member] Senior Secured Notes Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Fair value of James Hardie equity awards to be issued in exchange for certain AZEK equity awards Business Combination, Consideration Transferred, Equity Interests Issuable Business Combination, Consideration Transferred, Equity Interests Issuable Customer A Customer A [Member] Customer A [Member] Letter of Credit Letter of Credit [Member] Domestic Income (Loss) from Continuing Operations before Income Taxes, Domestic Less: imputed interest Operating and Finance Lease, Liability, Undiscounted Excess Amount Operating and Finance Lease, Liability, Undiscounted Excess Amount Schedule of Share-Based Compensation Expense Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Operating lease liabilities Current Operating Lease, Liability, Current Interest on lease liabilities Finance Lease, Interest Expense Document Fiscal Period Focus Document Fiscal Period Focus Settlements made in cash or in kind Standard and Extended Product Warranty Accrual, Decrease for Payments Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Summary Of Significant Accounting Policies [Table] Award Timing Method Award Timing Method [Text Block] December 2025 Grant December 2025 Grant [Member] December 2025 Grant Non-cash interest expense Noncash Interest Expense Noncash Interest Expense Award Type [Axis] Award Type [Axis] Foreign Currency Translation Adjustments Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Effect of foreign exchange Foreign Exchange Gain Loss In Asbestos Liability Foreign exchange gain or loss in the asbestos liability due to change in closing exchange rates between the currencies at the beginning and ending balance sheet dates. Schedule of Post Acquisition and Pro Forma Business Combination, Pro Forma Information [Table Text Block] Share-based Compensation Share-Based Payment Arrangement [Policy Text Block] Trading Symbol Trading Symbol Fiscal 2030 Lessee, Operating Lease, Liability, to be Paid, Year Four Number of members on the board of directors also serving on a related party board of directors Number Of Members On The Board Of Directors Also Serving On A Related Party Board Of Directors Number Of Members On The Board Of Directors Also Serving On A Related Party Board Of Directors Charges to cost of goods sold Standard and Extended Product Warranty Accrual, Increase for Warranties Issued Entity Address, City or Town Entity Address, City or Town Short-Term Debt, Type [Domain] Short-Term Debt, Type [Domain] Fiscal 2027 Operating and Finance Lease, Liability, Payments, Due Next Twelve Months Operating and Finance Lease, Liability, Payments, Due Next Twelve Months Finance leases, weighted-average discount rate Finance Lease, Weighted Average Discount Rate, Percent Effects of exchange rate changes on cash and cash equivalents, restricted cash and restricted cash - Asbestos Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Total deferred tax assets net of valuation allowance Deferred Tax Assets, Net of Valuation Allowance Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Restricted Stock Units (RSUs) Restricted Stock Units (RSUs) [Member] Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Total consideration transferred Business Combination, Consideration Transferred Entity Emerging Growth Company Entity Emerging Growth Company Fiscal 2029 Long-Term Debt, Maturity, Year Three Percentage of valuation allowance against foreign tax credit carry-forwards (as percent) Percentage Of Valuation Allowance Against Foreign Tax Credit Carry Forwards Percentage of valuation allowance against loss carry forwards. Finance leases, weighted-average remaining lease term Finance Lease, Weighted Average Remaining Lease Term Beginning balance (in shares) Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Number Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year Change in Fair Value as of Vesting Date of Prior Year Equity Awards Vested in Covered Year [Member] Unamortized debt issuance costs Debt Issuance Costs, Net Change in actuarial estimate Asbestos Change In Actuarial Estimate Asbestos change in actuarial estimate. Indefinite lived intangible assets other than goodwill Indefinite-Lived Intangible Assets (Excluding Goodwill) Workers’ compensation - Asbestos Workers Compensation Assets Asbestos Current Current amount of workers compensation receivable that is expected to be paid within one year of the balance sheet by the workers' compensation schemes or policies of the Former James Hardie Companies. Other Assets and Liabilities Other Assets And Liabilities [Member] Other Assets And Liabilities [Member] Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Accounts and Other Receivables Loans, Notes, Trade and Other Receivables Disclosure [Text Block] Schedule of Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Current: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Proceeds from senior secured notes Proceeds from Issuance of Senior Long-Term Debt Reclassification of foreign currency translation adjustments Reclassification Of Foreign Currency Translation Adjustments [Member] Reclassification Of Foreign Currency Translation Adjustments Income taxes payable Accrued Income Taxes, Current Exercise of vested stock options Stock Issued During Period, Value, Stock Options Exercised Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year Dividends or Other Earnings Paid on Equity Awards not Otherwise Reflected in Total Compensation for Covered Year [Member] Finance lease liability undiscounted excess amount not disclosed Finance Lease Liability Undiscounted Excess Amount Not Disclosed Finance Lease Liability Undiscounted Excess Amount Not Disclosed Schedule of Finite-Lived Intangible Assets, Future Amortization Expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract] Restricted Stock Units with Assumed and Replaeced Restricted Stock Units Assumed And Replaced [Member] Restricted Stock Units Assumed And Replaced Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Schedule of Indefinite-Lived Assets, Including Goodwill [Table] Schedule of Indefinite-Lived Assets, Including Goodwill [Table] Schedule of Indefinite-Lived Assets, Including Goodwill [Table] 2020 Omnibus Incentive Compensation Plan Restricted Stock Unit Activity Cash Settled Units Activity Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Income tax expense Total income tax expense Income tax expense Income Tax Expense (Benefit) Debt instrument, basis spread on variable rate Debt Instrument, Basis Spread on Variable Rate Siding & Trim Siding & Trim Segment [Member] Siding & Trim Segment Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Fair Value Hierarchy and NAV [Axis] Fair Value Hierarchy and NAV [Axis] Income Tax Payable Income Tax Payable [Member] Income Tax Payable [Member] Europe Europe Building Products [Member] Europe Building Products [Member] Property, plant and equipment, at cost Property, Plant and Equipment, Gross Assumed Equity Awards Assumed Equity Awards [Member] Assumed Equity Awards 5.875% Senior notes due 2031 5.875% Senior Secured Notes Due 2031 [Member] 5.875% Senior Secured Notes Due 2031 Other accrued liabilities and interest Increase (Decrease) In Other Accrued Liabilities And Interest Increase (Decrease) In Other Accrued Liabilities And Interest Employer matching contributions Defined Contribution Plan, Employer Discretionary Contribution Amount Restructuring, net Restructuring and Related Activities Disclosure [Text Block] Lease expense Operating Lease, Right-of-Use Asset, Periodic Reduction Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Acquisition of The AZEK Company Goodwill, Acquired During Period Proceeds from exercise of vested stock options Proceeds from Stock Options Exercised Cash consideration for The AZEK Company acquisition, net of cash acquired Payments to Acquire Businesses, Net of Cash Acquired Ireland Income Tax Paid, Federal, after Refund Received All Trading Arrangements All Trading Arrangements [Member] Equity Awards Adjustments, Footnote Equity Awards Adjustments, Footnote [Text Block] Total Shareholder Return Vs Peer Group Total Shareholder Return Vs Peer Group [Text Block] Average settlement amount per settled claim Average Settlement Amount Per Settled Claim Average settlement amount per settled claim. 5.000% Senior notes due 2028 5.000% Senior Unsecured Notes Due 2028 [Member] 5.000% Senior Unsecured Notes Due 2028 Assumptions Used to Fair Value Restricted Stock Grants Schedule Of Assumptions Used To Calculate Fair Value Of Restricted Stock Unit Table [Table Text Block] Tabular disclosure of the assumptions used to determine the fair value of restricted stock grants, including but not limited to expected volatility, dividend yield, risk free interest rate and the expected life. Loss Contingencies Commitments and Contingencies, Policy [Policy Text Block] Other Other items Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Deferred tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Asbestos [Abstract] Asbestos Beginning balance (in shares) Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Abstract] Accrued Product Warranties Standard Product Warranty, Policy [Policy Text Block] Net cash provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Debt instrument, term Debt Instrument, Term Effective Income Tax Rate Reconciliation [Table] Effective Income Tax Rate Reconciliation [Table] Shares cancelled Treasury Stock, Retired, Cost Method, Amount Property, plant and equipment useful life Property, Plant and Equipment, Useful Life Buildings Improvements Building Improvements [Member] Australia & New Zealand Australia & New Zealand Segment [Member] Australia & New Zealand Segment Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] PEO Total Compensation Amount PEO Total Compensation Amount Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Depreciation expense Depreciation Fiscal 2030 Finance Lease, Liability, to be Paid, Year Four Interest rate swap Derivative Liability, Subject to Master Netting Arrangement, before Offset Equity Components [Axis] Equity Components [Axis] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Number of reportable segments Number of Reportable Segments Advertising Costs Advertising Cost [Policy Text Block] Entity Address, Country Entity Address, Country Repayment of finance lease obligations Financing cash flows used for finance leases Finance Lease, Principal Payments Total current liabilities Liabilities, Current AICF operating costs paid - non claims-handling Asbestos Injuries Compensation Fund Operating Cost Paid Non Claim Handling Asbestos Injuries Compensation Fund operating cost paid non claim handling. Individual: Individual [Axis] Income Tax Authority [Domain] Income Tax Jurisdiction [Domain] Total right-of-use assets Lease, Right-of-Use Asset Lease, Right-of-Use Asset Document Annual Report Document Annual Report Claims and handling costs paid - Asbestos Asbestos Net Claim Paid Adjustment Including Handling Costs Incurred Paid Asbestos Net Claim Paid Adjustment Including Handling Costs Incurred Paid Proceeds from restricted investments - Asbestos Proceeds from restricted investments Asbestos Proceeds from restricted investments Asbestos Schedule Of Central Estimates, Net of Insurance Recoveries Estimated Asbestos Liability [Table Text Block] Tabular disclosure of the central estimate of the future Asbestos liability, net of insurance recoveries. Operating lease assets and liabilities, net Increase (Decrease) Operating Lease Assets and Liabilities, Net Increase (Decrease) Operating Lease Assets and Liabilities, Net Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Entity Interactive Data Current Entity Interactive Data Current Other Asbestos Adjustments, Other Asbestos Adjustments, Other Defined Contribution Plan, Matching Tranche [Domain] Defined Contribution Plan, Matching Tranche [Domain] Defined Contribution Plan, Matching Tranche [Domain] Time Deposits, October 16, 2026 Maturity Date Time Deposits, October 16, 2026 Maturity Date [Member] Time Deposits, October 16, 2026 Maturity Date Revenue Recognition Revenue from Contract with Customer [Policy Text Block] Non-cash consideration for AZEK acquisition Noncash Or Part Noncash Acquisition, Consideration Noncash Or Part Noncash Acquisition, Consideration Share-based payment awards Stock and executive compensation 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Entity Central Index Key PEO Name PEO Name Net sales Revenues Schedule of Debt Maturities Schedule of Maturities of Long-Term Debt [Table Text Block] Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year Prior Year End Fair Value of Equity Awards Granted in Any Prior Year that Fail to Meet Applicable Vesting Conditions During Covered Year [Member] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Comprehensive income, net of tax: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Defined Benefit Plan [Table] Defined Benefit Plan [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Raw materials and supplies Inventory, Raw Materials and Supplies, Gross Schedule of Fair Value of Interest Rate Swap Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Prepaid expenses and other assets Increase (Decrease) in Prepaid Expense and Other Assets Payment for freight services Payment for Freight Services Payment for Freight Services Accrued product warranties Product Warranty Accrual, Current Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Irish Statutory Tax Rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Long-term debt Total Long-term debt Long-Term Debt, Excluding Current Maturities 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Three Depreciation and Amortization Depreciation, Depletion, and Amortization [Policy Text Block] Entity Address, Address Line Three Entity Address, Address Line Three Deferred tax assets: Deferred Tax Assets, Net [Abstract] Gross Carrying Amount Finite-Lived Intangible Assets, Gross Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year Vesting Date Fair Value of Equity Awards Granted and Vested in Covered Year [Member] Entity Address, Address Line One Entity Address, Address Line One Entity Address, Address Line Two Entity Address, Address Line Two Research and development expenses Research and development costs Research and Development Expense Number of new claims, direct claims Loss Contingency, New Direct Claims Filed, Number Loss Contingency, New Direct Claims Filed, Number Accumulated Other Comprehensive Loss AOCI Attributable to Parent [Member] Provision for doubtful trade receivables Balance at beginning of period Balance at end of period Accounts Receivable, Allowance for Credit Loss, Current Investments [Domain] Investments [Domain] Business Combination, Asset Acquisition, Transaction between Entities under Common Control, and Joint Venture Formation [Abstract] Work-in-process Inventory, Work in Process, Gross Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Defined Contribution Plan, Matching Tranche Two Defined Contribution Plan, Matching Tranche Two [Member] Defined Contribution Plan, Matching Tranche Two Fair Value as of Grant Date Award Grant Date Fair Value Loss Contingency, Pending Claims, Number [Roll Forward] Loss Contingency, Pending Claims, Number [Roll Forward] Loss Contingency, Pending Claims, Number [Roll Forward] Tax loss carry-forwards Operating Loss Carryforwards Total share-based compensation expense Employee Benefits and Share-Based Compensation Changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Amount Credit facility, terminated Line of Credit Facility, Terminated Line of Credit Facility, Terminated Schedule of Long-term Debt Instruments Schedule of Long-Term Debt Instruments [Table Text Block] Dilutive effect of stock awards (in shares) Incremental Common Shares Attributable to Dilutive Effect of Share-Based Payment Arrangements Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Number of trading days Market Vesting Condition, Peer Group Comparison, Number of Trading Days Market Vesting Condition, Peer Group Comparison, Number of Trading Days Forfeited (in shares) Forfeited (in shares) Cancelled (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Unrecognized compensation cost related to share-based compensation cost Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Amount Related Party Transaction [Line Items] Related Party Transaction [Line Items] Deferred income taxes Deferred Income Taxes and Tax Credits Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Unremitted earnings benefit Effective Income Tax Rate Reconciliation, Unremitted Earnings Benefit, Amount Effective Income Tax Rate Reconciliation, Unremitted Earnings Benefit, Amount Counterparty Name [Domain] Counterparty Name [Domain] Fiscal 2028 Lessee, Operating Lease, Liability, to be Paid, Year Two Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Weighted-average remaining contractual term Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Total shares of AZEK common stock acquired (in shares) Business Combination, Consideration Transferred, Shares Of Equity Interests In Acquiree Acquired Business Combination, Consideration Transferred, Shares Of Equity Interests In Acquiree Acquired Germany GERMANY Schedule of Accounts Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Investment Type [Axis] Investment Type [Axis] Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount Secured standby loan facility maximum borrowing capacity Secured Standby Loan Facility Maximum Borrowing Capacity Maximum borrowing capacity under the standby loan facility entered into between the Obligors (AICF, Amaca, Amaba and ABN 60) and the State of New South Wales, Australia Total cash consideration paid Payments to Acquire Businesses, Gross Non-PEO NEO Non-PEO NEO [Member] Aggregate intrinsic value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Intrinsic Value Operating lease assets Deferred Tax Liabilities, Leasing Arrangements Fiscal 2029 Operating and Finance Lease, Liability, Payments, Due Year Three Operating and Finance Lease, Liability, Payments, Due Year Three Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Other Other Intangible Assets [Member] Land Land [Member] Award Type [Domain] Award Type [Domain] Fiscal 2027 Lessee, Operating Lease, Liability, to be Paid, Year One Term A-1 Facility, due 2028 Secured Debt A-1 [Member] Secured Debt A-1 Equity Awards Adjustments Equity Awards Adjustments [Member] Leasehold Improvements Leasehold Improvements [Member] Advertising costs Advertising Expense Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Contribution Plan, Matching Tranche One Defined Contribution Plan, Matching Tranche One [Member] Defined Contribution Plan, Matching Tranche One Canada CANADA Accounts and other receivables Increase (Decrease) in Accounts and Other Receivables Compensation Amount Outstanding Recovery Compensation Amount Deferred: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Dividend yield (per annum) Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Intangible assets Deferred Tax Assets, Intangible Assets Deferred Tax Assets, Intangible Assets Schedule of Provision for Doubtful Trade Debts Accounts Receivable, Allowance for Credit Loss [Table Text Block] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Statutory tax rate Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Australia AUSTRALIA 6.125% Senior notes due 2032 6.125% Senior Secured notes due 2032 [Member] 6.125% Senior Secured notes due 2032 3.625% Senior notes due 2026 3.625% Senior Unsecured Notes Due 2026 [Member] 3.625% Senior Unsecured Notes Due 2026 Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Fiscal 2027 Long-Term Debt, 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Measure Description Non-GAAP Measure Description [Text Block] Derivative [Table] Derivative [Table] Subtotal - Change in estimates Changes In Estimates Changes in estimates. Siding & Trim and Deck, Rail & Accessories Siding & Trim and Deck, Rail & Accessories [Member] Siding & Trim and Deck, Rail & Accessories Entity Small Business Entity Small Business Share issuance costs due to AZEK acquisition Payments of Stock Issuance Costs Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Interest and penalties recognized income tax expense Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Deferred tax on unremitted earnings Deferred Tax Liabilities, Undistributed Foreign Earnings Insurance receivable - Asbestos Insurance Receivable Asbestos Current The estimated receivable due within one year of the balance sheet date from various insurance policies and insurance companies for reimbursement and payment of asbestos claims. Debt Long-Term Debt [Text Block] Document Transition Report Document Transition Report Other assets - non-current Business Combination, Recognized Asset Acquired, Other Asset, Noncurrent Schedule of Gross Sales by Major Customers Schedules of Concentration of Risk, by Risk Factor [Table Text Block] Total Finance Lease, Liability, to be Paid Underlying Securities Award Underlying Securities Amount Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date Income Taxes Income Tax Disclosure [Text Block] Total lease liabilities Total lease liabilities Lease, Liability Lease, Liability Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Short-term leases Short-Term Lease, Cost Cash settlement of certain stock options Business Combination, Cash Settlement Of Stock Options Business Combination, Cash Settlement Of Stock Options Average Price Paid per Share (in dollars per share) Shares Acquired, Average Cost Per Share Risks and Uncertainties [Abstract] Document Type Document Type Non-cash restructuring expenses Non-Cash Restructuring Expenses Non-Cash Restructuring Expenses Name Outstanding Recovery, Individual Name Accounts and other receivables, net Total Accounts and Other Receivables, Net, Current Spain SPAIN Net sales Revenue Revenue from Contract with Customer, Excluding Assessed Tax Estimated fair value of the assumed equity awards Share-Based Compensation Arrangement By Share-Based Payment Award, Fair Value Of Awards Assumed In Business Combination Share-Based Compensation Arrangement By Share-Based Payment Award, Fair Value Of Awards Assumed In Business Combination Investment Income [Table] Investment Income [Table] Number of new claims, cross claims Loss Contingency, New Cross Claims Filed, Number Loss Contingency, New Cross Claims Filed, Number Total current assets Assets, Current Liabilities: Assets and Liabilities, Lessee [Abstract] Intangible assets acquired Finite-Lived Intangible Assets Acquired Range [Axis] Statistical Measurement [Axis] Forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Operating lease liabilities Deferred Tax Assets, Operating Lease Liabilities Deferred Tax Assets, Operating Lease Liabilities Unused capacity, commitment fee percentage Line of Credit Facility, Unused Capacity, Commitment Fee Percentage Other receivables Other Receivables, Net, Current Derivative, fixed interest rate Derivative, Fixed Interest Rate Asbestos - effect of foreign exchange Effective Income Tax Rate Reconciliation, Nondeductible Expense, Effect Of Foreign Exchange On Asbestos Income tax reconciliation nondeductible expense effect of foreign exchange on asbestos. Number of new claims Loss Contingency, New Claims Filed, Number Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Thereafter Operating and Finance Lease, Liability, Payments, Due after Year Five Operating and Finance Lease, Liability, Payments, Due after Year Five Shares issued, net of cash paid for shares withheld for taxes Payment, Tax Withholding, Share-Based Payment Arrangement Lessee operating lease liability undiscounted excess amount not disclosed Lessee Operating Lease Liability Undiscounted Excess Amount Not Disclosed Lessee Operating Lease Liability Undiscounted Excess Amount Not Disclosed Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] Discounted (but inflated) - High Range Of Discounted Actuarial Estimate Maximum Range of discounted actuarial estimate maximum. Threshold for individual percentage of long-lived assets Threshold For Individual Percentage Of Long-Lived Assets Threshold For Individual Percentage Of Long-Lived Assets Current liabilities: Liabilities, Current [Abstract] Cash consideration per share (in dollars per share) Business Combination, Price Per Share Risk free interest rate, minimum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Minimum Gain on sale of assets Gain (Loss) on Disposition of Assets Amount drawn under line of credit Long-Term Line of Credit Level 1 Fair Value, Inputs, Level 1 [Member] Share-based Compensation Arrangement by Share-based Payment Award, Compensation Cost [Line Items] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Line Items] Loss on foreign currency forward contracts Gain (Loss) On Foreign Currency Forwards Contracts, Asbestos Gain (Loss) On Foreign Currency Forwards Contracts, Asbestos Related Party Transaction [Table] Related Party Transaction [Table] Diluted (in dollars per share) Earnings Per Share, Diluted Asbestos claims paid Asbestos Net Claim Paid Adjustment Asbestos liability net claims paid. AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Schedule Of Asbestos Claims [Table] Schedule Of Asbestos Claims [Table] Schedule Of Asbestos Claims [Table] Cash payment for income taxes, net Income Taxes Paid Net Including Withholding Taxes Income taxes paid net including withholding taxes. Reconciliation to Consolidated Net Income [Abstract] Reconciliation to Consolidated Net Income [Abstract] Reconciliation to Consolidated Net Income Consolidation Items [Domain] Consolidation Items [Domain] Number of directors appointed by NSW government Number Of Directors Appointed To Variable Interest Entity By Government Number Of Directors Appointed To Variable Interest Entity By Government Auditor Location Auditor Location Time Deposits, July 24, 2026 Maturity Date Time Deposits, July 24, 2026 Maturity Date [Member] Time Deposits, July 24, 2026 Maturity Date Gross profit Gross Profit Domestic Tax Jurisdiction Domestic Tax Jurisdiction [Member] Accounts Payable and Accrued Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Equity Awards Equity Awards [Member] Equity Awards [Member] Discounted actuarial estimate, potential percent increase Discounted Actuarial Estimate Potential Percent Increase Discounted Actuarial Estimate Potential Percent Increase Income Taxes Paid Income Taxes Paid Income Taxes Paid, Net 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Two Cash consideration paid for common stock and stock options Payments To Acquire Common Stock And Stock Options In Acquisition Payments To Acquire Common Stock And Stock Options In Acquisition Long-term debt, gross Total Long-Term Debt, Gross Granted (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Asbestos liability Deferred Tax Assets Tax Deferred Expense Asbestos Liability The anticipated tax benefit available to the Company in future periods resulting from the Company's previous contributions to AICF in accordance with the Amended and Restated Final Funding Agreement (AFFA). Accrued payroll and employee benefits Employee-related Liabilities, Current Property, Plant and Equipment Property, Plant and Equipment Disclosure [Text Block] Total Lessee, Operating Lease, Liability, to be Paid Current borrowing capacity Line of Credit Facility, Current Borrowing Capacity Trade names Trade Names [Member] Cash consideration per share of AZEK common stock (in dollars per share) Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Cash Paid Per Acquiree Share Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Cash Paid Per Acquiree Share Expiration Date Trading Arrangement Expiration Date Ownership interest rate percentage (as percent) Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage 2031 Finite-Lived Intangible Asset, Expected Amortization, Year Five Property, plant and equipment, net Property, plant and equipment, net Property, Plant and Equipment, Net Restructuring, net Restructuring expenses Restructuring Charges Geographic Concentration Risk Geographic Concentration Risk [Member] Accrued customer rebates Accrued Customer Rebates, Current Accrued Customer Rebates, Current Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Inventories Inventory, Policy [Policy Text Block] Restructuring Cost [Table] Restructuring Cost [Table] Entity Current Reporting Status Entity Current Reporting Status Receivables [Abstract] Receivables [Abstract] Derivative [Line Items] Derivative [Line Items] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Irish Statutory Tax Rate Income tax expense computed at the statutory tax rates Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Adjustments to reconcile net income to net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Noncash Item [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] Share-based payment awards Effective Income Tax Rate Reconciliation, Nondeductible Expense, Share-Based Payment Arrangement, Percent Repayments of debt Repayments of Debt State income taxes, net of federal income tax benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Employee Benefit Plan Compensation and Employee Benefit Plans, Other than Share-Based Compensation [Text Block] Finance lease liabilities Current Finance Lease, Liability, Current Provision for obsolete finished goods and raw materials Inventory Valuation Reserves Current Fiscal Year End Date Current Fiscal Year End Date Ireland IRELAND Expected life in years Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Term Other liabilities - current Business Combination, Recognized Liability Assumed, Other Liability, Current Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Schedule of Components Accounts and Other Receivables Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Shares Available for Grant, Beginning balance (in shares) Shares Available for Grant, Ending balance (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Number of Shares Available for Grant Weighted Average Fair Value at Grant Date (A$) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Effect of changes in tax law or rates enacted in the current period Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Issuance of common stock in connection with the acquisition of The AZEK Company Stock Issued During Period, Value, Acquisitions Total amount of unrecognized tax benefits Unrecognized Tax Benefits Net assets acquired Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less) Potential diluted common shares outstanding (in shares) Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Weighted average common shares outstanding (Millions): Weighted Average Number of Shares Outstanding, Diluted [Abstract] Accounts payable and accrued liabilities Total Accounts Payable and Accrued Liabilities, Current Fiscal 2028 Long-Term Debt, Maturity, Year Two Leases Lessee, Operating Leases [Text Block] Net cash provided by (used in) financing activities Cash Provided by (Used in) Financing Activity, Including Discontinued Operation Measure: Measure [Axis] Thereafter Finite-Lived Intangible Asset, Expected Amortization, after Year Five Asbestos, deferred tax assets, beginning balance Asbestos, deferred tax assets, beginning balance Deferred Tax Assets Net Asbestos Noncurrent Non current portion of Australian tax benefits as of the balance sheet date that will be available to the Company in relation to the Company's contributions to the AICF. Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Maximum Dollar Value of Shares That May Yet be Purchased Under the Program (US$) Share Repurchase Program, Remaining Authorized, Amount Pension Actuarial Gain Accumulated Defined Benefit Plans Adjustment, Net Gain (Loss) Attributable to Parent [Member] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Forgone Recovery due to Violation of Home Country Law, Amount Forgone Recovery due to Violation of Home Country Law, Amount Risk free interest rate Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate Entity Tax Identification Number Entity Tax Identification Number Adjustment to provision Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease) Time Deposits, April 7, 2026 Maturity Date Time Deposits, April 7, 2026 Maturity Date [Member] Time Deposits, April 7, 2026 Maturity Date Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price Trade creditors Accounts Payable, Trade, Current Schedule of Basic and Dilutive Common Shares Outstanding Used in Determining Net Income Per Share Schedule of Weighted Average Number of Shares [Table Text Block] Common stock, shares issued (in shares) Common Stock, Shares, Issued Average settlement amount per case closed Average Settlement Amount Per Case Closed Average settlement amount per case closed. Operating leases, weighted-average remaining lease term Operating Lease, Weighted Average Remaining Lease Term Fiscal 2030 Long-Term Debt, Maturity, Year Four Goodwill and Other Intangible Assets Goodwill and Intangible Assets Disclosure [Text Block] Entity Public Float Entity Public Float Schedule of Changes in the Carrying Value of Goodwill Schedule of Goodwill [Table Text Block] Interest, net Interest, net Interest Expense, Nonoperating Trading Arrangement: Trading Arrangement [Axis] Income taxes payable Increase (Decrease) in Income Taxes Payable Total Shareholder Return Amount Total Shareholder Return Amount Defined Contribution Plan, Matching Tranche [Axis] Defined Contribution Plan, Matching Tranche [Axis] Defined Contribution Plan, Matching Tranche Security Exchange Name Security Exchange Name Foreign: Income Tax Paid, Foreign, after Refund Received Goodwill and intangible asset impairment Goodwill and Intangible Asset Impairment Discounted (but inflated) - Low Range Of Discounted Actuarial Estimate Minimum Range of discounted actuarial estimate minimum. Nontaxable or nondeductible items Expenses not deductible Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount New Zealand NEW ZEALAND Capital expenditures incurred but not yet paid Capital Expenditures Incurred but Not yet Paid Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-Lived Intangible Assets, Major Class Name [Domain] Other liabilities Other Liabilities, Current Asbestos liability actuarial estimate Asbestos Liability Actuarial Estimate Actuarial estimate of the Asbestos related liabilities, net of insurance recoveries. Share-based compensation Shares Granted, Value, Share-Based Payment Arrangement, after Forfeiture Statement [Line Items] Statement [Line Items] Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and Cash Equivalent AICF claims-handling costs incurred (paid) Asbestos Injuries Compensation Fund Claims Handling Costs Incurred (Paid) Asbestos injuries compensation fund claims handling costs incurred or paid. Risk free interest rate, maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Risk Free Interest Rate, Maximum Common Stock Common Stock [Member] Vested (in shares) Vested (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period Schedule of Property, Plant and Equipment Estimated Useful Lives Schedule Of Property Plant And Equipment Estimated Useful Lives [Table Text Block] Tabular disclosure of estimated useful lives of property, plant and equipment. Finance Leases Finance Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] Net (decrease) increase in cash and cash equivalents, restricted cash and restricted cash - Asbestos Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Organization and Significant Accounting Policies Significant Accounting Policies [Text Block] Range [Domain] Statistical Measurement [Domain] Property, plant and equipment Business Combination, Recognized Asset Acquired, Property, Plant, and Equipment Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Asbestos Net Liability [Roll Forward] Asbestos Net Liability [Roll Forward] Asbestos Net Liability [Roll Forward] Balance at beginning of period Balance at end of period Standard and Extended Product Warranty Accrual Weighted average interest rate of total debt Long-Term Debt, Weighted Average Interest Rate, at Point in Time Asbestos liability Asbestos Fund Liability Non Current Carrying value as of the balance sheet date of asbestos-related obligations incurred through that date and due after one year for estimated future asbestos claims. Interest rate swap Interest Rate Swap [Member] Debt Debt, Policy [Policy Text Block] AZEK AZEK [Member] AZEK Leases [Abstract] Leases [Abstract] James Hardie Common Shares issued (in shares) Business Combination, Consideration Transferred, Equity Interest, Share Issued, Number of Shares Type of Restructuring [Domain] Type of Restructuring [Domain] Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Basic (in dollars per share) Earnings Per Share, Basic Award Date [Axis] Award Date [Axis] Changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Percent Total deferred tax assets Deferred Tax Assets, Gross Other comprehensive income (loss) Other Comprehensive Income (Loss), Net of Tax Summary of Operating Segments Schedule of Segment Reporting Information, by Segment [Table Text Block] Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Schedule of Remaining Time Deposits Cash, Cash Equivalent, and Investment [Table Text Block] Asbestos Claims [Line Items] Asbestos Claims [Line Items] Asbestos Claims [Line Items] Exchange ratio (in shares) Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Entity Shares Issued Per Acquiree Share Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Entity Shares Issued Per Acquiree Share Fiscal 2029 Finance Lease, Liability, to be Paid, Year Three Indefinite-lived Intangible Assets [Line Items] Indefinite-Lived Intangible Assets [Line Items] Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Change in component, net of tax OCI, before Reclassifications, Net of Tax, Attributable to Parent Share-based compensation expense Share-Based Payment Arrangement, Expense Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current assets: Assets, Current [Abstract] Total liabilities and shareholders’ equity Liabilities and Equity Foreign Currency Translation/Remeasurement Foreign Currency Transactions and Translations Policy [Policy Text Block] Workers’ compensation - Asbestos Workers Compensation Assets Asbestos Noncurrent Noncurrent amount of workers compensation receivable that is expected to be paid after one year of the balance sheet by the workers' compensation schemes or policies of the Former James Hardie Companies. Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Number of Options Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding [Roll Forward] Reclassification from other comprehensive loss into net income, net of tax Reclassification from AOCI, Current Period, Net of Tax, Attributable to Parent Average closing price period Average Closing Common Stock Price Period Average closing common stock price period. Other deferred tax assets Deferred Tax Assets, Other Change in actuarial estimate - insurance receivable Change In Actuarial Estimate Insurance Receivables Change in actuarial estimate insurance receivables. Capital expenditures incurred but not yet paid Segment, Expenditure, Addition to Long-Lived Assets Guarantees [Abstract] Guarantees [Abstract] Accounting Policies [Abstract] Accounting Policies [Abstract] Asbestos liability Asbestos Fund Liability Current Carrying value as of the balance sheet date of asbestos-related obligations incurred through that date and due within one year for estimated future asbestos claims. Schedule of Operating Lease, Future Lease Payments For Non-Cancellable Lease Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Treasury Stock Treasury Stock, Common [Member] Total fair value vested Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value Pay vs Performance Disclosure [Line Items] Total operating lease liabilities Operating Lease, Liability Business Combination Business Combination [Text Block] Discounted actuarial estimate, potential period shift Discounted Actuarial Estimate, Potential Period Shift Discounted Actuarial Estimate, Potential Period Shift Finance leases Finance Lease, Right-of-Use Asset, Amortization Other liabilities Other Liabilities, Noncurrent Accounts payable and accrued liabilities Increase (Decrease) in Other Accounts Payable and Accrued Liabilities Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Long-term debt, current portion Less current portion Long-Term Debt, Current Maturities Company Selected Measure Amount Company Selected Measure Amount Fiscal 2029 Lessee, Operating Lease, Liability, to be Paid, Year Three Comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Name Measure Name Secured Debt Secured Debt [Member] Deferred income taxes Deferred Income Tax Liabilities, Net Impact on deferred income tax due to change in actuarial estimate Impact on deferred income tax due to change in actuarial estimate Impact on deferred income tax due to change in actuarial estimate. Threshold for individual percentage of net sales Threshold For Individual Percentage Of Net Sales Threshold For Individual Percentage Of Net Sales Tax credit carryforwards Foreign tax credit carry-forwards Deferred Tax Assets, Tax Credit Carryforwards, Foreign Foreign tax on domestic income Effective Income Tax Rate Reconciliation, Foreign Tax On Domestic Income, Percent Effective Income Tax Rate Reconciliation, Foreign Tax On Domestic Income, Percent Total debt Long-Term Debt Nondeductible acquisition costs Effective Income Tax Rate Reconciliation, Nondeductible Expense, Acquisition Costs, Percent Effective Income Tax Rate Reconciliation, Nondeductible Expense, Acquisition Costs, Percent Legal Entity [Axis] Legal Entity [Axis] Total assets Assets Cash Flows From Investing Activities Cash Provided by (Used in) Investing Activity, Continuing Operation [Abstract] 2027 Finite-Lived Intangible Asset, Expected Amortization, Year One AZEK Acquisition AZEK Acquisition [Member] AZEK Acquisition Vested (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Schedule of Numbers of Open Claims, New Claims and Closed Claims and Average Settlement Per Settled Claim and Case Closed Schedule Of Asbestos Claims Activity And Average Settlement Per Settled Claim And Case Closed Table [Table Text Block] Tabular disclosure of roll forward activity of asbestos related claims and average settlement per settled claim and case closed. Restricted Cash and Cash Equivalents Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Geographical [Domain] Geographical [Domain] Income Taxes Income Tax, Policy [Policy Text Block] Other expenses Segment Reporting, Other Segment Item, Amount Acquired finite-lived intangible assets, weighted average useful life Acquired Finite-Lived Intangible Assets, Weighted Average Useful Life Concentration Risk Type [Axis] Concentration Risk Type [Axis] Inventories Inventory Disclosure [Text Block] Restructuring costs Restructuring Costs 2030 Finite-Lived Intangible Asset, Expected Amortization, Year Four Fiscal 2027 Finance Lease, Liability, to be Paid, Year One Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Non-cash ROU assets obtained in exchange for new lease liabilities Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Total assets acquired Business Combination, Recognized Asset Acquired, Asset Document Financial Statement Error Correction [Flag] Document Financial Statement Error Correction [Flag] State income taxes, net of federal income tax benefit US state income taxes, net of the federal benefit Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Net Unfunded AFFA Liability, net of tax Net Unfunded AFFA Liability, Net of Tax [Member] Net Unfunded AFFA Liability, Net of Tax [Member] Net Unfunded AFFA liability, net of tax, Beginning Balance Net Unfunded AFFA liability, net of tax, Ending Balance Asbestos Net Liability Net Tax Asbestos net liability in accordance with the Amended and Restated Final Funding Agreement, net of tax. Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Business Acquisition, Acquiree [Domain] Business Combination [Domain] Operating Leases Lessee, Operating Lease, Liability, to be Paid, Fiscal Year Maturity [Abstract] Related Party Related Party [Member] Schedule of Income Tax Expense Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Number of closed claims Loss Contingency, Claims Settled and Dismissed, Number Plan Name [Axis] Plan Name [Axis] Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] Other movements Asbestos Liability Other Changes Other movements in the asbestos liability, either increasing or decreasing the liability. PEO PEO [Member] Proceeds from term loans Proceeds from Issuance of Secured Debt Number of open claims at beginning of period Number of open claims at end of period Loss Contingency, Pending Claims, Number Non-Cash Investing and Financing Activities Noncash Investing and Financing Items [Abstract] Intangible assets Deferred Tax Liabilities, Intangible Assets Income Tax Paid, by Individual Jurisdiction [Line Items] Income Tax Paid, by Individual Jurisdiction [Line Items] Purchase obligation, to be paid, next five fiscal years Purchase Obligation, To Be Paid, Next Five Fiscal Years Purchase Obligation, To Be Paid, Next Five Fiscal Years United States United States of America UNITED STATES Changes in operating assets and liabilities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Schedule of Changes in Product Warranty Provision Schedule of Product Warranty Liability [Table Text Block] Expected volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Time Deposits Time Deposits Retained Earnings Retained Earnings [Member] Income Tax Authority [Axis] Income Tax Jurisdiction [Axis] Insurance receivable - Asbestos Increase (Decrease) In Insurance Receivable Asbestos Increase decrease in insurance receivable asbestos. Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-Based Payment Arrangement [Abstract] Cash and cash equivalents, restricted cash and restricted cash - Asbestos at beginning of period Cash and cash equivalents, restricted cash and restricted cash - Asbestos at end of period Total Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Equipment write-offs, including disposal costs Facility Closing [Member] Intangible assets, net Intangible Assets, Net (Excluding Goodwill) Asbestos adjustments Asbestos adjustments Asbestos adjustments Asbestos Adjustments Comprised of changes in actuarial estimates received as of March 31 each year and the effect of foreign exchange movements in the asbestos related assets and liabilities which are denominated in Australian dollars. Customer Concentration Risk Customer Concentration Risk [Member] Dividends [Abstract] Transaction costs Business Combination, Transaction Cost, Excluding Separately Recognized Transaction Senior Unsecured Notes Senior Unsecured Notes [Member] Senior Unsecured Notes Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Business Combination [Table] Business Combination [Table] Notional amount Derivative, Notional Amount Schedule of ROU Assets and Lease Liabilities Assets and Liabilities, Lessee [Table Text Block] Assets and Liabilities, Lessee [Table Text Block] Income Tax Paid, by Individual Jurisdiction [Table] Income Tax Paid, by Individual Jurisdiction [Table] Schedule of Allocation of Purchase Price Business Combination, Recognized Asset Acquired and Liability Assumed [Table Text Block] Liability Awards Liability Awards [Member] Liability Awards [Member] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Credit Facilities Credit Facilities [Member] Credit Facilities Schedule Of Asbestos Claims [Line Items] Schedule Of Asbestos Claims [Line Items] Schedule Of Asbestos Claims [Line Items] Employer matching contribution for deferred compensation plan, percent of match (up to) Deferred Compensation Arrangement with Individual, Cash Awards Granted, Percentage Proceeds from revolving credit facilities Proceeds from Long-Term Lines of Credit Issuance of stock awards in connection with the acquisition of The AZEK Company Adjustments to Additional Paid in Capital, Share-Based Awards Issued In Acquisitions Adjustments to Additional Paid in Capital, Share-Based Awards Issued In Acquisitions Total deferred taxes, net Deferred Tax Liabilities, Net Long-lived assets Long-Lived Assets Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Europe Europe Segment [Member] Europe Segment Number of directors appointed by Company Number Of Directors Appointed To Variable Interest Entity By Company Number Of Directors Appointed To Variable Interest Entity By Company Employer matching contribution, percent of match Defined Contribution Plan, Employer Matching Contribution, Percent of Match Schedule of Stock Options Roll Forward Schedule of Stock Options Roll Forward [Table Text Block] Tax settlement Tax Adjustments, Settlements, and Unusual Provisions Effective Income Tax Rate Reconciliation [Line Items] Effective Income Tax Rate Reconciliation [Line Items] Total lease expense Lease, Cost Goodwill Amount of goodwill recognized Balance, beginning Balance, ending Goodwill Schedule of Lease Expense Lease, Cost [Table Text Block] Number of restricted stock units (in shares) Share Based Compensation Arrangement By Share Based Payment Award Restricted Stock Units Number Share based compensation arrangement by share based payment award restricted stock units number. Domestic Deferred Federal Income Tax Expense (Benefit) Assets held for sale Asset, Held-for-Sale, Not Part of Disposal Group, Current Non-US Non-US [Member] Insurance Receivables Insurance Receivables [Member] Insurance Receivables [Member] Auditor Name Auditor Name Concentration Risk [Table] Concentration Risk [Table] Inventories Business Combination, Recognized Asset Acquired, Inventory, Current Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward] Movement in Standard and Extended Product Warranty Accrual, Increase (Decrease) [Roll Forward] Pension adjustments Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, after Tax Asbestos, net liability, beginning balance Asbestos net liability, ending balance Asbestos Net Liability Asbestos net liability in accordance with the Amended and Restated Final Funding Agreement. Net Unfunded AFFA Liability Net Unfunded AFFA Liability [Member] Net Unfunded AFFA Liability [Member] Supplemental Disclosure of Cash Flow Activities Supplemental Cash Flow Information [Abstract] Operating loss carryforwards, valuation allowance Operating Loss Carryforwards, Valuation Allowance Accounts and other receivables Business Combination, Recognized Asset Acquired, Receivable, Current Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Other Performance Measure, Amount Other Performance Measure, Amount Weighted Average Exercise Price (US$) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Outstanding, Weighted Average Exercise Price [Abstract] Schedule of Reconciliation of Restricted Cash and Restricted Cash - Asbestos Restrictions on Cash and Cash Equivalents [Table Text Block] Debt issuance costs paid Payments of Debt Issuance Costs Currency translation adjustments Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Time Deposits, 27 January 2027 Maturity Date Time Deposits, January 27, 2027 Maturity Date [Member] Time Deposits, January 27, 2027 Maturity Date Fair Value Measurements Fair Value Measurement, Policy [Policy Text Block] Related and Nonrelated Parties [Domain] Related and Nonrelated Parties [Domain] Amount Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Asbestos Asbestos [Text Block] Represents disclosure of asbestos provision and related assets and liabilities. Letter of Credit and Bank Guarantees Letter of Credit and Bank Guarantees [Member] Letter of Credit and Bank Guarantees Derivative Instrument [Axis] Derivative Instrument [Axis] Acquisition-related cost incurred Business Combination, Separately Recognized Transaction, Acquisition-Related Cost, Incurred Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Leases Lessee, Finance Leases [Text Block] Additional paid-in capital Additional Paid in Capital, Common Stock Entity [Domain] Entity [Domain] Other exit costs Other Restructuring [Member] Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation October 2025 Grant October 2025 Grant [Member] October 2025 Grant Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table Aggregate Change in Present Value of Accumulated Benefit for All Pension Plans Reported in Summary Compensation Table [Member] Purchase obligation, due within one year Purchase Obligation, to be Paid, Year One Cash flow hedge gain (loss) reclassified to earnings Interest Rate Cash Flow Hedge Gain (Loss) Reclassified to Earnings, Net Cash paid for interest Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Basis of Presentation Basis of Accounting, Policy [Policy Text Block] Operating lease right-of-use-assets Operating leases, net Operating Lease, Right-of-Use Asset Effective tax rate Effective tax rate Effective Income Tax Rate Reconciliation, Percent Accrued product warranties Product Warranty Accrual, Noncurrent Operating leases Operating Lease, Cost Restricted Stock Units Service Vesting Restricted Stock Units Service Vesting [Member] Restricted stock units service vesting. Cash Flows From Operating Activities Cash Provided by (Used in) Operating Activity, Continuing Operation [Abstract] Plan Name [Domain] Plan Name [Domain] Acquisition related expenses Business Combination, Acquisition-Related Cost, Expense Estimated weighted average amortization, period of recognition Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Exercised (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Valuation allowance Valuation allowance Deferred Tax Assets, Valuation Allowance Equity [Abstract] Equity [Abstract] Goodwill and Other Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Buildings Building [Member] Insurance receivable - Asbestos Insurance Receivable Asbestos Noncurrent The estimated receivable due after one year from the balance sheet date from various insurance policies and insurance companies for reimbursement and payment of asbestos claims. Derivative Instruments Derivatives, Policy [Policy Text Block] Segment and Geographic Information Segment Reporting Disclosure [Text Block] Domestic Current Federal Tax Expense (Benefit) Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] 2020 Omnibus Incentive Compensation Plan 2020 Omnibus Incentive Compensation Plan [Member] 2020 Omnibus Incentive Compensation Plan Other liabilities - non-current Business Combination, Recognized Liability Assumed, Other Liability, Noncurrent Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] Accumulated Other Comprehensive Loss Comprehensive Income (Loss) Note [Text Block] Amortization Amortization of Intangible Assets Leases Lessee, Leases [Policy Text Block] Selling, general and administrative expenses Selling, General and Administrative Expense Deferred income taxes Deferred Income Tax Assets, Net Line of credit, issued but undrawn Line Of Credit, Issued But Undrawn Line Of Credit, Issued But Undrawn Accumulated Other Comprehensive Loss Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Depreciation and amortization Depreciation, Depletion and Amortization Schedule of Revenues from External Customers and Long-Lived Assets [Table] Schedule of Revenues from External Customers and Long-Lived Assets [Table] Finished goods Inventory, Finished Goods, Gross Revolving Facility Revolving Credit Facility [Member] Accounts Receivable Accounts Receivable [Policy Text Block] Debt issuance cost, writeoff Deferred Debt Issuance Cost, Writeoff Statutory tax rate Taxes on foreign income Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Total finance lease liabilities Finance Lease, Liability Arrangement Duration Trading Arrangement Duration Net loss Business Combination, Acquiree's Earnings (Loss) since Acquisition Date, Actual Expected volatility, maximum Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate, Maximum Segments [Axis] Segments [Axis] Payment received in accordance with AFFA Payments Received In Accordance With Amended And Restated Final Funding Agreement Payments received in accordance with amended and restated final funding agreement. Fair Value by Liability Class [Domain] Fair Value by Liability Class [Domain] Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Trade receivables Accounts Receivable, before Allowance for Credit Loss, Current Thereafter Long-Term Debt, Maturity, after Year Five Share-Based Compensation Share-Based Payment Arrangement [Text Block] Cash and cash equivalents Business Combination, Recognized Asset Acquired, Cash and Cash Equivalent Assets Assets [Abstract] Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Restricted cash and cash equivalents - Asbestos Restricted Cash And Cash Equivalents Asbestos The carrying amounts of cash and cash equivalent items which are restricted to the settlement of asbestos claims and payments of the operating costs of the Asbestos Injuries Compensation Fund. Amounts are classified as current as they are highly liquid. Debt Instrument [Axis] Debt Instrument [Axis] Forfeited (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value Business Combination [Line Items] Business Combination [Line Items] Credit Facility [Domain] Credit Facility [Domain] Shareholders’ equity: Equity, Attributable to Parent [Abstract] Shares repurchased Treasury Stock, Value, Acquired, Cost Method Cash flow hedge gain (loss) to be reclassified during next 12 months, before tax Interest Rate Cash Flow Hedge Gain (Loss) to be Reclassified During Next 12 Months, Net Interest rate (as percent) Debt Instrument, Interest Rate, Stated Percentage Operating lease liabilities Non-Current Operating Lease, Liability, Noncurrent Entity Voluntary Filers Entity Voluntary Filers Nondeductible acquisition costs Effective Income Tax Rate Reconciliation, Nondeductible Expense, Acquisition Costs, Amount Effective Income Tax Rate Reconciliation, Nondeductible Expense, Acquisition Costs, Amount Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant [Roll Forward] Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Entity Registrant Name Entity Registrant Name Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Central Estimate – Undiscounted and Uninflated Undiscounted And Uninflated [Member] Undiscounted And Uninflated [Member] Recognized tax deduction Asbestos Recognized Tax Deduction The tax deduction relating to the AICF contribution. Stock issuance costs in connection with the acquisition of The AZEK Company Adjustments to Additional Paid in Capital, Stock Issued, Issuance Costs Tax Credit Carryforward [Line Items] Tax Credit Carryforward [Line Items] Machinery and Equipment Machinery and equipment Machinery and Equipment [Member] Granted (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Related and Nonrelated Parties [Axis] Related and Nonrelated Parties [Axis] Schedule of Finite-Lived Intangible Assets Schedule of Finite-Lived Intangible Assets [Table Text Block] Repayments of revolving credit facilities Repayments of Long-Term Lines of Credit Restatement Determination Date: Restatement Determination Date [Axis] Foreign Deferred Foreign Income Tax Expense (Benefit) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Schedule of Restructuring, Net Restructuring and Related Costs [Table Text Block] Income tax expense: Income Tax Expense (Benefit), Continuing Operations [Abstract] Reclassification of other comprehensive income Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Effect of changes in tax law or rates enacted in the current period Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Name Trading Arrangement, Individual Name Business Interruption Loss [Domain] Business Interruption Loss [Domain] Debt instrument, face amount Debt Instrument, Face Amount Cash Settled Units Activity Share-Based Payment Arrangement, Activity [Table Text Block] Net deferred tax remeasurement Effective Income Tax Rate Reconciliation, Net Deferred Tax Remeasurement, Amount Effective Income Tax Rate Reconciliation, Net Deferred Tax Remeasurement, Amount Asbestos, income tax payable, beginning balance Asbestos, income tax payable, ending balance Income Tax Payable Asbestos Australian tax deduction available to be taken by the Company resulting from the Company's previous contributions to AICF. Fair value of consideration of James Hardie common shares Business Combination, Consideration Transferred, Equity Interest Name Awards Close in Time to MNPI Disclosures, Individual Name Income before income taxes: Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest [Abstract] Weighted average grant date fair value (in USD per share) Beginning balance (in dollars per share) Ending balance (in dollars per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Restructuring Type [Axis] Restructuring Type [Axis] Change in actuarial estimate - asbestos liability Change In Actuarial Estimate Asbestos Liability Change in actuarial estimate asbestos liability. Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Employee contribution, percent matched Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Current taxes receivable, CARES Act Income Taxes Receivable, CARES Act Income Taxes Receivable, CARES Act Schedule of Finance Lease, Future Lease Payments For Non-Cancellable Lease Finance Lease, Liability, to be Paid, Maturity [Table Text Block] Depreciable and amortizable assets Deferred Tax Liabilities, Other Finite-Lived Assets Liability Class [Axis] Liability Class [Axis] Foreign Tax Jurisdiction Foreign Tax Jurisdiction [Member] Auditor Firm ID Auditor Firm ID Segments [Domain] Segments [Domain] Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Summary Of Significant Accounting Policies [Line Items] Summary Of Significant Accounting Policies [Line Items] Summary of Significant Accounting Policies [Line Items] Inventories Increase (Decrease) in Inventories Assets: Assets, Noncurrent [Abstract] Less accumulated depreciation Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Earnings Per Share Earnings Per Share, Policy [Policy Text Block] Total Operating and Finance Lease Liabilities, Payments, Due [Abstract] Operating and Finance Lease Liabilities, Payments, Due [Abstract] Senior Notes Senior Notes [Member] Insurance recoveries Insurance Recoveries Asbestos Adjustment The amount recovered from insurance related to asbestos claims. Cash Settled Units Cash Settled Units [Member] Cash Settled Units Unsecured Revolving Credit Facility Unsecured Revolving Credit Facility [Member] Unsecured Revolving Credit Facility Total liabilities assumed Business Combination, Recognized Liability Assumed, Liability All Executive Categories All Executive Categories [Member] Schedule of Deferred Tax Assets and Liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Common stock, Euro 0.59 par value, 2.0 billion shares authorized; 580,174,308 shares issued and outstanding at March 31, 2026 and 429,818,781 shares issued and outstanding at March 31, 2025 Common Stock, Value, Issued Finance lease right-of-use-assets Finance leases, net Finance Lease, Right-of-Use Asset, after Accumulated Amortization Prepaid expenses and other current assets Business Combination, Recognized Asset Acquired, Prepaid Expense and Other Asset, Current Restricted short-term investments - Asbestos Restricted Short-Term Investments Asbestos Restricted Short-Term Investments Asbestos Integration costs Business Combination, Integration-Related Cost, Expense Commitments and contingencies (Note 15) Commitments and Contingencies AZEK debt repaid as of the acquisition date Repayments Of Debt Assumed To Acquire Business Repayments Of Debt Assumed To Acquire Business Restricted Cash and Investments Restricted Cash and Investments [Member] Restricted Cash and Investments [Member] Cash flow hedge gain (loss) to be reclassified during next 12 months, after tax Interest Rate Cash Flow Hedge Gain (Loss) To Be Reclassified During Next 12 Months, Net Of Tax Interest Rate Cash Flow Hedge Gain (Loss) To Be Reclassified During Next 12 Months, Net Of Tax Intangible assets Business Combination, Recognized Asset Acquired, Identifiable Intangible Asset, Finite-Lived Business Acquisition [Axis] Business Combination [Axis] Granted (in shares) Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Granted In Period Share Based Compensation Arrangement By Share Based Payment Award Number Of Shares Available For Grant Granted In Period Summary of Geographical Information Revenue from External Customers by Geographic Areas [Table Text Block] Secured standby loan facility amounts outstanding Secured Standby Loan Facility, Amount Outstanding Secured Standby Loan Facility, Amount Outstanding Concentration Risk [Line Items] Concentration Risk [Line Items] Schedule Of Asbestos Adjustments Schedule Of Asbestos Adjustments [Table Text Block] Tabular disclosure of components of asbestos adjustments. Total deferred taxes, net Deferred Tax Assets, Net Workers’ compensation - Asbestos Workers Compensation Liabilities Asbestos Noncurrent Noncurrent portion of workers' compensation claims (due after one year or the normal operating cycle, if longer) that are expected to be met by the workers' compensation schemes or policies of the Former James Hardie Companies. Since these amounts are expected to be paid by the workers' compensation schemes or policies, the company records an equivalent workers' compensation receivable. PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Non-cash remeasurements (decreasing) increasing ROU assets Lease, Right-of-Use Asset, Increase (Decrease) due to Remeasurement Lease, Right-of-Use Asset, Increase (Decrease) due to Remeasurement Forfeited (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period Deferred Tax Assets Deferred Tax Assets [Member] Deferred Tax Assets [Member] Inventory step-up adjustment Business Combination, Provisional Information, Initial Accounting Incomplete, Adjustment, Inventory Revenue from Contract with Customer [Abstract] Revenue from Contract with Customer [Abstract] Fair value of senior notes Debt Instrument, Fair Value Disclosure Deferred tax liabilities, net Business Combination, Recognized Liability Assumed, Deferred Tax Liability JHX stock price at grant date (A$ per share) Share Based Compensation Arrangement By Share Based Payment Award Fair Value Assumptions Grant Date Stock Price Share based compensation arrangement by share based payment award fair value assumptions grant date stock price. Cash paid to AICF Contribution to AICF Payment To Fund Under the terms of the Amended and Restated Final Funding Agreement (AFFA), a wholly owned Australian subsidiary (the Performing Subsidiary) has an obligation to make payments to the AICF on an annual basis. The amount of these annual payments is dependent on several factors, including the Company's free cash flow (as defined by the AFFA), actuarial estimations, actual claims paid, operating expenses of the AICF and the annual cash flow cap. Other Countries Other Countries [Member] Other countries. Derivative Contract [Domain] Derivative Contract [Domain] Proceeds from issuance of shares Proceeds from Issuance of Common Stock All Individuals All Individuals [Member] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Purchases of property, plant and equipment Payments to Acquire Property, Plant, and Equipment Name Forgone Recovery, Individual Name Capitalized interest Interest Paid, Capitalized, Investing Activity Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested Year-over-Year Change in Fair Value of Equity Awards Granted in Prior Years That are Outstanding and Unvested [Member] Purchase of restricted investments - Asbestos Purchase of restricted investments Asbestos Purchase of restricted investments Asbestos Acquisition-related cost, intangible expense Business Combination, Acquisition-Related Cost, Intangible Expense Business Combination, Acquisition-Related Cost, Intangible Expense Foreign exchange impact Goodwill, Foreign Currency Translation, Gain (Loss) Undiscounted (but inflated) - Low Range Of Un Discounted Actuarial Estimate Minimum Range of undiscounted actuarial estimate minimum. Foreign tax on domestic income Foreign taxes on domestic income Effective Income Tax Rate Reconciliation, Foreign Taxes On Domestic Income, Amount Income tax reconciliation foreign taxes on domestic income Gain on sale of land Gain (Loss) on Sale of Properties Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Schedule of Finite-Lived Intangible Assets [Table] Intangible Asset, Finite-Lived [Table] Fiscal 2030 Operating and Finance Lease, Liability, Payments, Due Year Four Operating and Finance Lease, Liability, Payments, Due Year Four Geographical [Axis] Geographical [Axis] Other, net Increase (Decrease) in Other Operating Assets and Liabilities, Net Restricted cash and cash equivalents Restricted Cash And Cash Equivalents Excluding Amounts For Asbestos Claims Restricted cash and cash equivalents excluding amounts for asbestos claims. Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] CSU Assumed And Replaced CSU Assumed And Replaced [Member] CSU Assumed And Replaced Revenue Business Combination, Pro Forma Information, Pro Forma Revenue Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Title of 12(b) Security Title of 12(b) Security Impairment of Long-Lived Assets Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy [Policy Text Block] Income per share: Net income per share of common stock: Earnings Per Share [Abstract] Fiscal 2031 Lessee, Operating Lease, Liability, to be Paid, Year Five New South Wales, Australia New South Wales, Australia [Member] New South Wales, Australia [Member] Short-Term Debt, Type [Axis] Short-Term Debt, Type [Axis] Asbestos-related Accounting Policies Asbestos Policy [Policy Text Block] Disclosure of background of asbestos liability, Asbestos Injuries Compensation Fund and accounting policies related to asbestos-related assets and liabilities. Total Number of Shares Purchased (in shares) Treasury Stock, Shares, Acquired Asbestos Liability Asbestos Liability [Member] Asbestos Liability [Member] Thereafter Finance Lease, Liability, to be Paid, after Year Five Exercised (in dollars per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Award Timing Disclosures [Line Items] Schedule of Components of Inventories Schedule of Inventory, Current [Table Text Block] Capital Management Equity [Text Block] Net income Net income Net Income (Loss) Attributable to Parent Operating leases: Operating Lease, Liability [Abstract] Construction in progress Construction in Progress [Member] Other creditors and accruals Other Accrued Liabilities, Current Schedule of Tax at Statutory Rates Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Allowance for Doubtful Accounts Receivable [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Vesting period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Restricted Stock Units (Market Condition) Restricted Stock Units Market Condition [Member] Restricted Stock Units Market Condition. Other Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Shares repurchased Payments for Repurchase of Common Stock Adoption Date Trading Arrangement Adoption Date Reclassification Reclassification, Comparability Adjustment [Policy Text Block] Tax Credit Carryforward [Table] Tax Credit Carryforward [Table] Customer [Axis] Customer [Axis] Cash Flows From Financing Activities Cash Provided by (Used in) Financing Activity, Continuing Operation [Abstract] Customer Relationships Customer Relationships [Member] Operating income Operating income Operating Income (Loss) Line of Credit Line of Credit [Member] Cash paid to settle award Share-Based Payment Arrangement, Cash Used to Settle Award Retained earnings Retained Earnings (Accumulated Deficit) Schedule of Stock Activity Class of Treasury Stock [Table Text Block] Central Estimate – Undiscounted but Inflated Undiscounted But Inflated [Member] Undiscounted But Inflated [Member] Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested Year-end Fair Value of Equity Awards Granted in Covered Year that are Outstanding and Unvested [Member] Workers’ compensation - Asbestos Workers Compensation Liability Asbestos Current Current portion of workers' compensation claims (due within one year or within the normal operating cycle if longer) that are expected to be met by the workers' compensation schemes or policies of the Former James Hardie Companies. Since these amounts are expected to be paid by the workers' compensation schemes or policies, the company records an equivalent workers' compensation receivable. Employer matching contribution for 401(k) defined compensation plan, percent of match (up to) Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent Cash Flow Hedges Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table Aggregate Grant Date Fair Value of Equity Award Amounts Reported in Summary Compensation Table [Member] Other deferred tax liabilities Deferred Tax Liabilities, Other Payables and Accruals [Abstract] Payables and Accruals [Abstract] Statement [Table] Statement [Table] Other expense (income), net Other expense (income), net Other Nonoperating Income (Expense) Schedule of Consideration Transferred Business Combination [Table Text Block] Deferred income tax expense Deferred Income Tax Expense (Benefit) Nontaxable or nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent Sales Revenue, Net Revenue Benchmark [Member] Other foreign jurisdictions Other Foreign Tax Jurisdiction, Other [Member] Total consideration transferred Business Combination, Recognized Asset Acquired to Liability Assumed, Excess (Less), and Goodwill Finance lease liabilities Non-Current Finance Lease, Liability, Noncurrent Repayments of term loans Repayments of Unsecured Debt All Adjustments to Compensation All Adjustments to Compensation [Member] Amendment Flag Amendment Flag Undiscounted (but inflated) - High Range Of Un Discounted Actuarial Estimate Maximum Range of undiscounted actuarial estimate maximum. Termination Date Trading Arrangement Termination Date Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Deck, Rail & Accessories Deck, Rail & Accessories Segment [Member] Deck, Rail & Accessories Segment Contingent Shares Not Expected To Vest Contingent Shares Not Expected To Vest [Member] Contingent Shares Not Expected To Vest [Member] Operating leases, weighted-average discount rate Operating Lease, Weighted Average Discount Rate, Percent Net sales Business Combination, Acquiree's Revenue since Acquisition Date, Actual Basic (in shares) Basic common shares outstanding (in shares) Weighted Average Number of Shares Outstanding, Basic Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table] Options exercisable (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Number Segment Reporting [Abstract] Segment Reporting [Abstract] Cost of goods sold Cost of Revenue Debt Disclosure [Abstract] Debt Disclosure [Abstract] Schedule of Unvested Restricted Stock Units Roll Forward Schedule of Unvested Restricted Stock Units Roll Forward [Table Text Block] Write-offs, net of recoveries Accounts Receivable, Allowance for Credit Loss, Writeoff Restructuring and Related Activities [Abstract] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Non-cash remeasurements (decreasing) increasing lease liabilities Lease Liabilities, Increase (Decrease) due to Remeasurement Lease Liabilities, Increase (Decrease) due to Remeasurement Common stock, par value (in Euros per share) Common Stock, Par or Stated Value Per Share Schedule of Indefinite-Lived Assets, Including Goodwill [Line Items] Schedule of Indefinite-Lived Assets, Including Goodwill [Line Items] [Line Items] for Schedule of Indefinite-Lived Assets, Including Goodwill [Table] Unremitted earnings benefit Effective Income Tax Rate Reconciliation, Unremitted Earnings Benefit, Percent Effective Income Tax Rate Reconciliation, Unremitted Earnings Benefit, Percent Income taxes receivable Income Taxes Receivable, Current Granted (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Gross Use of Estimates Use of Estimates, Policy [Policy Text Block] Operating cash flows used for finance leases Finance Lease, Interest Payment on Liability Insider Trading Arrangements [Line Items] AZEK Company Inc. AZEK Company Inc. [Member] AZEK Company Inc. Total liabilities Liabilities Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Non-cash charge related to step up of inventory Noncash Expense Related To Set Up Of Inventory Noncash Expense Related To Set Up Of Inventory Fiscal 2031 Finance Lease, Liability, to be Paid, Year Five Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Repurchased face amount Debt Instrument, Repurchased Face Amount Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Audit Information [Abstract] Audit Information Cash for AZEK common stock Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Cash Paid For Acquiree Shares Business Combination, Consideration Transferred, Equity Interests Issued and Issuable, Cash Paid For Acquiree Shares Issuance of common stock Stock Issued During Period, Value, New Issues Replacement Service-Based Stock Option Awards Replacement Service-Based Stock Option Awards [Member] Replacement Service-Based Stock Option Awards Consolidation Items [Axis] Consolidation Items [Axis] Interest Rate Short-Term Debt, Percentage Bearing Fixed Interest Rate Counterparty Name [Axis] Counterparty Name [Axis] Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member]