Accumulated Amortization Finite-Lived Intangible Assets, Accumulated Amortization Expected return on assets Defined Benefit Plan, Expected Return (Loss) on Plan Assets Schedule of expected benefit payments Schedule of Expected Benefit Payments [Table Text Block] Award Timing Predetermined Award Timing Predetermined [Flag] Entity File Number Entity File Number Additional Paid-in Capital Additional Paid-in Capital [Member] Tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Amount From 2008 to 2014 From 2008 to 2014 [Member] From 2008 to 2014 Tabular List, Table Tabular List [Table Text Block] Target Allocation Ranges Defined Benefit Plan, Plan Assets, Target Allocation, Percentage Recently Adopted Accounting Standards and Recently Issued Accounting Standards (Not Yet Adopted) New Accounting Pronouncements, Policy [Policy Text Block] Machinery and equipment Machinery and Equipment, Gross Period-end account balances with non-consolidated affiliates, shown as related party balances Schedule of Related Party Transactions [Table Text Block] Secured Overnight Financing Rate (SOFR) Secured Overnight Financing Rate (SOFR) [Member] Realized losses (gains), net Realized Gains Losses On Derivative Net Realized gains losses on derivative net. Goodwill [Line Items] Goodwill [Line Items] Adjustment to Compensation: Adjustment to Compensation [Axis] EnvironmentalLossContingencyStatementOfFinancialPositionExtensibleEnumerationNotDisclosedFlag EnvironmentalLossContingencyStatementOfFinancialPositionExtensibleEnumerationNotDisclosedFlag EnvironmentalLossContingencyStatementOfFinancialPositionExtensibleEnumerationNotDisclosedFlag Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Catastrophic Event [Axis] Catastrophic Event [Axis] AV Minerals (Netherlands) N.V. AV Minerals (Netherlands) N.V. [Member] AV Minerals (Netherlands) N.V. Other [Member] Other Plan Assets [Member] Other Plan Assets [Member] Total current Current Income Tax Expense (Benefit) Total contributions Payment for Pension and Other Postretirement Benefits Payment for Pension and Other Postretirement Benefits Prior year adjustments Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Amount Operating and Finance Lease Liabilities Operating and Finance Lease Liabilities Operating and Finance Lease Liabilities Adjustment to Compensation, Amount Adjustment to Compensation Amount Percentage of total net sales Purchases from Rio Tinto as a percentage of total combined metal purchases Concentration Risk, Percentage Financial Instruments And Commodity Contracts [Abstract] Financial Instruments And Commodity Contracts [Abstract] Financial Instruments and Commodity Contracts. Pension Benefits [Member] Defined Benefit Pension Plans [Member] Pension Plan [Member] Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Debt Instrument, Unamortized Discount (Premium) and Debt Issuance Costs, Net Other assets Increase (Decrease) in Other Operating Assets Consolidation Policy Consolidation, Policy [Policy Text Block] Series 2025A Bonds, due June 2032 Series 2025A Bonds, due June 2032 [Member] Series 2025A Bonds, due June 2032 Employee Stock Option Share-Based Payment Arrangement, Option [Member] Property, Plant and Equipment [Table] Property, Plant and Equipment [Table] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Income taxes paid Income Taxes Paid Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Finance Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Percent Effective Income Tax Rate Reconciliation, Percent [Abstract] Liabilities, Netting Adjustment Derivative Liability, Master Netting Adjustment Derivative Liability, Master Netting Adjustment Ultimate health care cost trend rate Defined Benefit Plan, Ultimate Health Care Cost Trend Rate Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), before Reclassification, Tax Non-cash restructuring and impairment charges Fixed asset charges Asset Impairment Charges Total equity of our common shareholder Equity, Attributable to Parent Other comprehensive income (loss): Other Comprehensive Income (Loss), Net of Tax [Abstract] Insider Trading Policies and Procedures [Line Items] New York NEW YORK Schedule of property, plant and equipment Property, Plant and Equipment [Table Text Block] Stock issued during period (in shares) Stock Issued During Period, Shares, New Issues Risks and Uncertainties Concentration Risk, Credit Risk, Policy [Policy Text Block] LIABILITIES AND SHAREHOLDER'S EQUITY Liabilities and Equity [Abstract] Cover [Abstract] Europe Segment Europe Segment [Member] Europe Segment Maximum Maximum [Member] Weighted Average Exercise Price (Indian Rupees/USD per share), Exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Weighted Average Exercise Price Triggering Event [Domain] Triggering Event [Domain] Triggering Event [Domain] Weighted average assumptions used to determine benefit obligations, Average compensation growth Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Rate of Compensation Increase Forfeited/Cancelled Aggregate Intrinsic Value, Forfeited/Cancelled Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Intrinsic Value 2025 Efficiency Plan 2025 Efficiency Plan [Member] 2025 Efficiency Plan Intangible assets, net Net Carrying Amount Finite-Lived Intangible Assets, Net Income Tax Details [Line Items] Income Tax Contingency [Line Items] Increase in maximum borrowing capacity Line of Credit Facility, Increase In Maximum Borrowing Capacity Line of Credit Facility, Increase In Maximum Borrowing Capacity Non-PEO NEO Average Total Compensation Amount Non-PEO NEO Average Total Compensation Amount Debt Instrument [Line Items] Debt Instrument [Line Items] Schedule of Share-based Compensation by Award [Table] Schedule of Share-Based Compensation Arrangements by Share-Based Payment Award [Table] Weighted Average Remaining Contractual Term Share-Based Compensation Arrangement By Share-Based Payment Award, Non Option Equity Instruments, Weighted Average Remaining Contractual Term [Abstract] Share-Based Compensation Arrangement By Share-Based Payment Award, Non Option Equity Instruments, Weighted Average Remaining Contractual Term [Abstract] Adjustment to Non-PEO NEO Compensation Footnote Adjustment to Non-PEO NEO Compensation Footnote [Text Block] Total debt, carrying value Debt, Long-Term and Short-Term, Combined Amount Commitment and applicable borrowing base Debt Instrument, Covenant, Percentage Applied on Lesser of ABL Revolver Commitment and Applicable Borrowing Base Debt Instrument, Covenant, Percentage Applied on Lesser of ABL Revolver Commitment and Applicable Borrowing Base Retirement Benefits [Abstract] Retirement Benefits [Abstract] Forgone Recovery due to Disqualification of Tax Benefits, Amount Forgone Recovery due to Disqualification of Tax Benefits, Amount Non-Rule 10b5-1 Arrangement Terminated Non-Rule 10b5-1 Arrangement Terminated [Flag] Income before income tax provision Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Entity Shell Company Entity Shell Company Schedule of Revenue by Major Customers, by Reporting Segments [Table] Schedule of Revenue by Major Customers, by Reporting Segments [Table] Schedule of Long-term Debt Instruments [Table] Schedule of Long-Term Debt Instruments [Table] Proceeds from issuance of long-term and short-term borrowings Proceeds from Issuance of Debt Other Defined Benefit Plans, other costs Defined Benefit Plans, other costs Loss Contingency Nature [Axis] Loss Contingency Nature [Axis] Unfunded Plan [Member] Defined Benefit Plan, Unfunded Plan [Member] Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Operating Segments Operating Segments [Member] Schedule of Cash Flow, Supplemental Disclosures Schedule of Cash Flow, Supplemental Disclosures [Table Text Block] Other intangible assets Other Intangible Assets, Net Comprehensive income (loss) attributable to noncontrolling interest, net of tax Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Award Timing MNPI Considered Award Timing MNPI Considered [Flag] Line of Credit Facility [Table] Line of Credit Facility [Table] Prior service credit Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, Prior Service Cost (Credit), before Tax Balance as of beginning of period Balance as of end of period Restructuring Reserve Letter of Credit Letter of Credit [Member] Domestic (Canada) Income (Loss) from Continuing Operations before Income Taxes, Domestic Other nonrecurring expense Other Nonrecurring Expense Number of countries Company operates in Number of Countries in which Entity Operates Total compensation expense related to SARs and RSUs under the long term incentive plans Share-Based Payment Arrangement, Expensed and Capitalized, Amount [Table Text Block] Operating Lease, Liability, Current Operating Lease, Liability, Current Nontaxable or nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Percent [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Weighted average assumptions used to determine net periodic benefit cost, Average compensation growth Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Rate of Compensation Increase Accounts Receivable Receivable [Policy Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Defined Benefit Plans and Other Postretirement Benefit Plans Table Text Block [Line Items] Award Timing Method Award Timing Method [Text Block] Litigation Case [Domain] Litigation Case [Domain] LME Copper and Zinc Forward Contracts LME Copper and Zinc Forward Contracts [Member] Copper Forward Contracts [Member] Furniture, Fixtures and Equipment Furniture and Fixtures [Member] Award Type [Axis] Award Type [Axis] Currency Translation Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Hedging Relationship [Domain] Hedging Relationship [Domain] Contributions to employee benefit plans Schedule of Employer Contributions to Pension and Other Postretirement Plans [Table Text Block] Tabular disclosure of employer contributions to pension and other postretirement plans Parent Company Parent Company [Member] Investment, Name [Domain] Investment, Name [Domain] Share-Based Compensation Share-Based Payment Arrangement [Policy Text Block] 2030 Lessee, Operating Lease, Liability, to be Paid, Year Four Business Combinations Business Combination [Policy Text Block] Valuation Allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Percent Other Short-Term Debt Other Short-Term Debt [Member] Other Short-Term Debt Entity Address, City or Town Entity Address, City or Town Short-term Debt, Type [Domain] Short-Term Debt, Type [Domain] Finance Lease, Weighted Average Discount Rate, Percent Finance Lease, Weighted Average Discount Rate, Percent Factoring expense Factoring Expense Factoring Expense Schedule of intangible assets, net Intangible Assets Disclosure [Text Block] Effect of exchange rate changes on cash Effect of Exchange Rate on Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Net deferred income tax assets Deferred Tax Assets, Net of Valuation Allowance Currency gains Defined Benefit Plan, Plan Assets, Foreign Currency Translation Gain (Loss) Asia Segment Asia Segment [Member] Asia Segment Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Revolving credit facilities and other, net Proceeds from (Repayments of) Short-Term Debt RSUs [Member] Restricted Stock Units (RSUs) [Member] Restricted Stock Units (RSUs) [Member] Income Statement Location [Domain] Statement of Income Location, Balance [Domain] Employee-related expenses Severance Costs Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Other Europe Other Europe [Member] Other Europe [Member] Settlements (3) Unrecognized Tax Benefits, Decrease Resulting from Settlements with Taxing Authorities Entity Emerging Growth Company Entity Emerging Growth Company 3 years Long-Term Debt, Maturity, Year Three Restructuring liabilities, short-term Restructuring Reserve, Current Total postretirement amounts recognized in accumulated other comprehensive loss Beginning balance in accumulated other comprehensive loss Total postretirement amounts recognized in accumulated other comprehensive loss Defined Benefit Plan, Accumulated Other Comprehensive (Income) Loss, before Tax Finance Lease, Weighted Average Remaining Lease Term Finance Lease, Weighted Average Remaining Lease Term Near-term Benefit Payments [Member] Near Term Benefit Payments [Member] Near Term Benefit Payments [Member] 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] Debt issuance costs, net Debt Issuance Costs, Net Total loss (gain) recognized in other expenses (income), net Derivative, Gain (Loss) on Derivative, Net 2027 Defined Benefit Plan, Expected Future Benefit Payment, Year One Restructuring Reserve [Roll Forward] Restructuring Reserve [Roll Forward] Less: interest Finance Lease, Liability, Undiscounted Excess Amount Common stock, shares outstanding (in shares) Common Stock, Shares, Outstanding Additions Charged to Expense Accounts Receivable, Credit Loss Expense (Reversal) Other Assets, Fair Value Disclosure Other Assets, Fair Value Disclosure Equity contribution from our common shareholder Equity, Increase From Contribution, Amount Equity, Increase From Contribution, Amount Weighted Average Remaining Contractual Term, Exercisable Share-Based Payment Arrangement, Option, Exercise Price Range, Exercisable, Weighted Average Remaining Contractual Term Loss (gain) on foreign exchange remeasurement of debt Unrealized Gain (Loss), Foreign Currency Transaction, before Tax Current provision: Current Income Tax Expense (Benefit), Continuing Operations [Abstract] Other long–term assets Assets for Plan Benefits, Defined Benefit Plan Accrued income taxes Accrued Income Taxes, Current 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] Schedule of disclosure on geographic areas, long-lived assets in individual foreign countries by country Schedule of Disclosure on Geographic Areas, Long-Lived Assets in Individual Foreign Countries by Country [Table Text Block] 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] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Prepaid expenses and other current assets Prepaid Expense and Other Assets, Current Semi-Annually and Remainder of Principal Payable at Maturity Semi-Annually and Remainder of Principal Payable at Maturity [Member] Semi-Annually and Remainder of Principal Payable at Maturity Maturities of long-term debt outstanding Maturities of Long-Term Debt [Abstract] Number of RSUs Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Number of Shares [Roll Forward] Interest rates Debt Instrument, Interest Rate, Effective Percentage Entity Address, Postal Zip Code Entity Address, Postal Zip Code Restatement Determination Date Restatement Determination Date Income tax provision Income tax provision (benefit) Income tax provision Income tax provision (benefit) Income tax provision Income Tax Expense (Benefit) Variable rate Debt Instrument, Basis Spread on Variable Rate Unsecured debt Unsecured Debt Pension Adjustments Service Cost Pension Adjustments Service Cost [Member] Derivatives designated as hedging instruments: Designated as Hedging Instrument [Member] Fair Value, Hierarchy [Axis] Fair Value Hierarchy and NAV [Axis] Start Up Cost Start Up Cost Start Up Cost Hedging Relationship [Axis] Hedging Relationship [Axis] Changzhou Plant Changzhou Plant [Member] Changzhou Plant Change in fair value of effective portion of hedges, net of tax provision (benefit), included in other comprehensive (loss) income Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification and Tax Series 2026A Bonds, due June 2033 Series 2026A Bonds, due June 2033 [Member] Series 2026A Bonds, due June 2033 Prime Rate Prime Rate [Member] Retirement Plan Funding Status [Domain] Defined Benefit Plan, Funding Status [Domain] Applicable borrowing base Debt Instrument, Percentage of the Lesser of Total Revolver Commitment to Applicable Borrowing Base Debt Instrument, Percentage of the Lesser of Total Revolver Commitment to Applicable Borrowing Base Employer discretionary contribution amount Defined Contribution Plan, Employer Discretionary Contribution Amount Prior service cost Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), after Reclassification Adjustment, before Tax China Bank Loans, due August 2027 China Bank Loans [Member] China Bank Loans Other Income and Expenses [Abstract] Other Income and Expenses [Abstract] Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Tax (benefit) provision Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, Tax, Parent Accumulated depreciation and amortization Accumulated depreciation and amortization Property, Plant, and Equipment and Finance Lease Right-of-Use Asset, Accumulated Depreciation and Amortization Acquisition of business and other investments Payments to Acquire Businesses, Net of Cash Acquired Domestic - Federal Tax 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] Fair value of financial instruments and commodity contracts Derivative Assets (Liabilities), at Fair Value, Net, by Balance Sheet Classification [Abstract] Accrued expenses and other current liabilities Accrued expenses and other current liabilities Accrued Liabilities, Current Enacted tax rate changes Income tax reconciliation, Canadian Statutory Rate, Change in Enacted Tax Rate The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the Canadian statutory income tax rates to pretax income from continuing operations, that is attributable to changes in the income tax rates under enacted tax laws in the period. Imputed income Effective Income Tax Rate Reconciliation, Tax Exempt Income, Percent Litigation Contingencies Commitments and Contingencies, Policy [Policy Text Block] Other deferred taxes, valuation allowance Deferred Tax Assets, Other, Valuation Allowance Deferred Tax Assets, Other, Valuation Allowance Other Adjustments Non-deductible expenses and other, net Effective Income Tax Rate Reconciliation, Other Adjustments, Amount Deferred income tax liabilities: Deferred Tax Liabilities, Gross [Abstract] Pension plans with accumulated benefit obligations in excess of plan assets, accumulated benefit obligation Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Accumulated Benefit Obligation Outstanding, beginning of period (shares) Outstanding, end of period (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] Antidumping Duties Antidumping Duties [Member] Antidumping Duties Net cash (used in) provided by operating activities Cash Provided by (Used in) Operating Activity, Including Discontinued Operation Proceeds from insurance claims Proceeds from Insurance Settlement, Investing Activities Property, plant and equipment, useful life Property, Plant and Equipment, Useful Life Revenues from External Customers and Long-Lived Assets [Line Items] Revenues from External Customers and Long-Lived Assets [Line Items] Schedule of Equity Method Investments [Line Items] Schedule of Equity Method Investments [Line Items] Equity Valuation Assumption Difference, Footnote Equity Valuation Assumption Difference, Footnote [Text Block] Metal contracts Aluminium Contracts [Member] Aluminium Contracts [Member] Aluminium contracts. PEO Total Compensation Amount PEO Total Compensation Amount Foreign Tax Income Tax Paid, Foreign, after Refund Received [Abstract] Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Depreciation expense related to property, plant and equipment, net included in depreciation and amortization Depreciation 2030 Finance Lease, Liability, to be Paid, Year Four Assets, Netting Adjustment Derivative Asset, Master Netting Adjustment Derivative Asset, Master Netting Adjustment Statement, Equity Components [Axis] Equity Components [Axis] Property, Plant and Equipment [Line Items] Property, Plant and Equipment [Line Items] Hindalco SARs [Member] Hindalco SARs [Member] Hindalco SARs [Member] Loans and Leases Receivable Disclosure [Table] Loans and Leases Receivable Disclosure [Table] Non-Rule 10b5-1 Arrangement Adopted Non-Rule 10b5-1 Arrangement Adopted [Flag] Depreciation and amortization Deferred Tax Liabilities, Property, Plant and Equipment and Intangibles Amount of deferred tax liabilities attributable to taxable temporary differences from property, plant, and equipment and intangible assets. Number of reportable segments Number of Reportable Segments Total share-based liabilities paid Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Share-Based Liabilities Paid Unamortized Carrying Value Adjustments Debt Instrument, Unamortized Discount (Premium), Net Total net periodic benefit cost recognized Defined Benefit Plan, Net Periodic Benefit Cost, Including Proportionate Share of Non-consolidated Affiliates Defined Benefit Plan, Net Periodic Benefit Cost, Including Proportionate Share of Non-consolidated Affiliates Other Other Restructuring Costs 7. CONSOLIDATION Variable Interest Entity Disclosure [Text Block] Entity Address, State or Province Entity Address, State or Province Finance Lease, Principal Payments Finance Lease, Principal Payments 2030 Defined Benefit Plan, Expected Future Benefit Payment, Year Four Total current liabilities Liabilities, Current Liabilities, Current Cumulative restructuring charges through March 31, 2026 Restructuring and Related Cost, Cost Incurred to Date Individual: Individual [Axis] Income Tax Authority [Domain] Income Tax Jurisdiction [Domain] Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Right-of-Use Asset Obtained in Exchange for Finance Lease Liability Document Annual Report Document Annual Report Voreppe, TFR, and Pensions Kasse Sierre Voreppe, TFR, and Pensions Kasse Sierre [Member] Voreppe, TFR, and Pensions Kasse Sierre Adjustment to reconcile proportional consolidation Adjustment To Eliminate Proportional Consolidation Adjustment to eliminate proportional consolidation. Proportionate share of non-consolidated affiliates' pension costs Defined Benefit Plan, Net Periodic Benefit Cost, Attributable to Proportionate Share of Non-consolidated Affiliates Defined Benefit Plan, Net Periodic Benefit Cost, Attributable to Proportionate Share of Non-consolidated Affiliates Other Debt, due through December 2020 Other Debt, due through December 2020 [Member] Other Debt, due through December 2020 [Member] Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Percentage of total combined metal purchases Schedule Of Entity Wide Information Percentage Of Product Purchases [Table Text Block] Schedule of entity wide information percentage of product purchases. Environmental Remediation Contingency [Axis] Environmental Remediation Contingency [Axis] Entity Interactive Data Current Entity Interactive Data Current Catastrophic Event [Domain] Catastrophic Event [Domain] Loss Contingency, Nature [Domain] Loss Contingency, Nature [Domain] Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Weighted-Average Interest Crediting Rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Weighted-Average Interest Crediting Rate Defined Benefit Plan, Funded (Unfunded) Status of Plan, Total Defined Benefit Plan, Funded (Unfunded) Status of Plan Currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercisable, Intrinsic Value Property insurance recoveries Property Insurance Recoveries Property Insurance Recoveries Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items] Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Current portion of long–term debt Current portion of long-term debt Long-Term Debt and Lease Obligation, Current Proceeds from equity contribution from our common shareholder Proceeds from Contributions from Parent Property, Plant and Equipment, Type [Axis] Long-Lived Tangible Asset [Axis] Exchange translation items Income Tax Reconciliation, Canadian Statutory Income Tax Rate, Exchange Translation Adjustments The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the year/accounting period and the expected income tax expense or benefit computed by applying the Canadian statutory income tax rates to pretax income from continuing operations, that is attributable to exchange translation adjustments. Settlement/curtailment (gain) loss Settlement/curtailment gain Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement and Curtailment 2028 Finance Lease, Liability, to be Paid, Year Two Tax rate differences on foreign earnings Income Tax Reconciliation, Canadian Statutory Income Tax Rate, Tax Rate Differences on Foreign Earnings The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the year/accounting period and the expected income tax expense or benefit computed by applying the Canadian statutory income tax rates to pretax income from continuing operations, that is attributable to tax rate differences on foreign earnings.. Finance Lease, Right-of-Use Asset, Accumulated Amortization Finance Lease, Right-of-Use Asset, Accumulated Amortization Unfunded pension plans Defined Contribution Plan Employers Contribution To Unfunded Pension Plan Defined contribution plan employer's contribution to unfunded pension plan. Goodwill Goodwill and Intangible Assets, Goodwill, Policy [Policy Text Block] Foreign Tax Income Tax Paid, Foreign, after Refund Received, Percent Income Tax Paid, Foreign, after Refund Received, Percent 2028 Defined Benefit Plan, Expected Future Benefit Payment, Year Two Long-term Growth Assets [Member] Long term growth assets [Member] Long term growth assets [Member] Allowance as a percentage of gross accounts receivable Allowance as a percentage of gross accounts receivable Allowance as a percentage of gross accounts receivable Other long–term assets Other long–term assets Other Assets, Noncurrent Name of Major Customer [Domain] Customer [Domain] Accrued interest payable Interest Payable, Current Entity Central Index Key Entity Central Index Key PEO Name PEO Name Total debt Debt, Long-term and Short-term, Combined Amount, Principal Amount Including short-term borrowing and current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date before deducting unamortized discount or premiums (if any). Asset retirement obligation Asset Retirement Obligation Principal repayment requirements for total debt over the next five years and thereafter 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] Restructuring Activities Costs Associated with Exit or Disposal Activities or Restructurings, Policy [Policy Text Block] Outstanding Aggregate Erroneous Compensation Amount Outstanding Aggregate Erroneous Compensation Amount Schedule of Defined Benefit Plans Disclosures [Table] Defined Benefit Plan [Table] Schedule of Segment Reporting Information, by Segment [Table] Schedule of Segment Reporting Information, by Segment [Table] Invoices confirmed during the year Supplier Finance Program, Obligation, Addition 15. FINANCIAL INSTRUMENTS AND COMMODITY CONTRACTS Financial Instruments Disclosure [Text Block] Nontaxable or nondeductible items Effective Income Tax Rate Reconciliation, Nondeductible Expense, Amount [Abstract] Fair values of financial instruments and commodity contracts Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Exercise Price Award Exercise Price Entity Filer Category Entity Filer Category Derivative, Nonmonetary Notional Amount, Energy Measure Derivative, Nonmonetary Notional Amount, Energy Measure Benefits paid Benefits paid Defined Benefit Plan, Benefit Obligation, Benefits Paid Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Share-based Awards Other than Options Share-Based Payment Arrangement, Nonvested Award, Excluding Option, Cost Not yet Recognized, Amount Canada Statutory Tax Rate Effective Income Tax Rate Reconciliation, at Federal Statutory Income Tax Rate, Percent Third Parties Nonrelated Party [Member] 2029 Finite-Lived Intangible Asset, Expected Amortization, Year Three Balance Sheet Location [Axis] Statement of Financial Position Location, Balance [Axis] Financing receivable Financing Receivable, before Allowance for Credit Loss Bonds Bonds [Member] 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] Sierre flood losses, net of recoveries (Gain) Loss From Catastrophes (Gain) Loss From Catastrophes Entity Address, Address Line One Entity Address, Address Line One Research and development expenses Research and Development Expense Forfeited/Cancelled (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Forfeitures and Expirations Accumulated Other Comprehensive Loss AOCI Attributable to Parent AOCI Attributable to Parent [Member] Allowance for credit losses Allowance for credit losses — third parties Balance at Beginning of Period Balance at End of Period Accounts Receivable, Allowance for Credit Loss, Current Retirement Plan Funding Status [Axis] Defined Benefit Plan, Funding Status [Axis] Losses recognized on balance sheet remeasurement currency exchange contracts, net Gain (Loss) on Foreign Currency Derivative Instruments Not Designated as Hedging Instruments Work in process Inventory, Work in Process, Gross Sale of stock, consideration received Sale of Stock, Consideration Received Per Transaction Loans and Leases Receivable Disclosure [Line Items] Loans and Leases Receivable Disclosure [Line Items] 17. FAIR VALUE MEASUREMENTS Derivative Instruments and Hedging Activities Disclosure [Text Block] Amortization — prior service credit Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Exercised (Indian Rupees/USD per share) Share-based Compensation Arrangements by Share-based Payment Award, Equity Instruments Other than Options, Exercises in Period, Weighted Average Exercise Price Weighted average price at which instrument holders acquired shares when converting their equity instruments (other than options) into shares. Aggregate principal amount (more than) Line of Credit Facility, Periodic Payment, Principal Sierre business interruption insurance recoveries Insurance Recoveries Fair Value as of Grant Date Award Grant Date Fair Value Schedule of other nonoperating income (expense) Schedule of Other Nonoperating Income (Expense) [Table Text Block] Operating loss carryforwards Operating Loss Carryforwards Non-cash charges related to Sierre flooding Non-Cash Charges Related To Natural Disasters Non-Cash Charges Related To Natural Disasters Changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Amount Idle fixed costs Labor and Related Expense Granted (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period Total expenses Costs and Expenses Forteited/Cancelled (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeited in Period Liability for Unpaid Claim and Claim Adjustment Expense, Change [Table] Liability for Unpaid Claim and Claim Adjustment Expense, Change [Table] Related Party Transaction [Line Items] Related Party Transaction [Line Items] Income tax settlements Effective Income Tax Rate Reconciliation, Tax Settlement, Amount Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Counterparty Name [Domain] Counterparty Name [Domain] 5.875% Senior Notes due September 2026 5.875% Senior Notes due September 2026 [Member] 5.875% Senior Notes due September 2026 2028 Lessee, Operating Lease, Liability, to be Paid, Year Two Adjustment To PEO Compensation, Footnote Adjustment To PEO Compensation, Footnote [Text Block] Germany GERMANY Consolidation [Abstract] Consolidation [Abstract] Consolidation Title Trading Arrangement, Individual Title Peer Group Total Shareholder Return Amount Peer Group Total Shareholder Return Amount 2029 Defined Benefit Plan, Expected Future Benefit Payment, Year Three Non-PEO NEO Non-PEO NEO [Member] Letters of credit outstanding Letters of Credit Outstanding, Amount Brazil BRAZIL Accumulated Other Comprehensive Income (Loss) [Line Items] Accumulated Other Comprehensive Income (Loss) [Line Items] Other Intangible Assets Other Intangible Assets [Member] Award Type [Domain] Award Type [Domain] 2027 Lessee, Operating Lease, Liability, to be Paid, Year One Alunorf Aluminum Norf GmbH [Member] Aluminum Norf GmbH [Member] Noncontrolling interests Equity, Attributable to Noncontrolling Interest Equity Awards Adjustments Equity Awards Adjustments [Member] Other, net Other Noncash Income (Expense) Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Foreign exchange translation and remeasurement Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Percent Disaggregation of Revenue [Line Items] Disaggregation of Revenue [Line Items] Canada CANADA Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Compensation Amount Outstanding Recovery Compensation Amount Deferred provision: Deferred Income Tax Expense (Benefit), Continuing Operations [Abstract] Schedule of revenue from external customers attributed to foreign countries by geographic area Schedule of Revenue from External Customers Attributed to Foreign Countries by Geographic Area [Table Text Block] Switzerland SWITZERLAND Curtailments, settlements and special termination benefits Defined Benefit Plan, Curtailments, Settlements, and Special Termination Benefits The amount of decrease that is related to an event that significantly reduces the expected years of future service of present employees or eliminates for a significant number of employees the accrual of defined benefits for some or all of their future services. And/or The amount of decrease that relates to an irrevocable action that relieves the employer (or the plan) of primary responsibility for a benefit obligation and eliminates significant risks related to the obligation and the assets used to effect the settlement. Examples of transactions that constitute a settlement include (a) making lump-sum cash payments to plan participants in exchange for their rights to receive specified benefits and (b) purchasing nonparticipating annuity contracts. And/or The amount of increase related to special termination benefits offered to and accepted by employees in connection with their termination of employment that are only offered for a short period of time. A situation involving termination benefits may also involve a curtailment. Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] Dividend yield Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Dividend Rate Currency exchange contracts Foreign Exchange Contract [Member] Recovery of Erroneously Awarded Compensation Disclosure [Line Items] Aerospace and industrial plate Aerospace Products [Member] Aerospace Products Retirement Plan Type [Domain] Retirement Plan Type [Domain] China CHINA MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Percent Rio Tinto Alcan Rio Tinto Alcan [Member] Rio Tinto Alcan [Member] Schedule of amounts recognized in other comprehensive income (loss) Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Documents Incorporated by Reference Documents Incorporated by Reference [Text Block] Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] Finance Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Amount [Abstract] Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Long–term debt, net of current portion Carrying Value, Long-term debt, net of current portion Long-Term Debt and Lease Obligation Short-term borrowings and current portion of long-term debt due within one year Long-Term Debt, Maturity, Year One Summary disclosures of financial amounts Summary of amounts related to forfaiting and factoring activities [Table Text Block] Summary of amounts related to forfaiting and factoring activities [Table] Total deferred income tax liabilities Deferred Tax Liabilities, Gross Summary of the impact on AOCI and earnings of derivative instruments designated as cash flow hedges Schedule of Cash Flow Hedges Included in Accumulated Other Comprehensive Income (Loss) [Table Text Block] 5 years Long-Term Debt, Maturity, Year Five AluInfra Services SA AluInfra Services SA [Member] AluInfra Services SA [Member] Aggregate Pension Adjustments Service Cost Aggregate Pension Adjustments Service Cost [Member] Other Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Amount Inventories Inventories Inventory, Net Payment for settlement Defined Benefit Plan, Benefit Obligation, Payment for Settlement Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Minimum Minimum [Member] Canadian statutory tax rate Effective Income Tax Rate Reconciliation, at Canadian Statutory Income Tax Rate The Canadian statutory tax rate applicable under enacted tax laws to the Company's pretax income from continuing operations for the period. Company Selected Measure Name Company Selected Measure Name Accrual for environmental loss contingencies Accrual for Environmental Loss Contingencies Dubai UNITED ARAB EMIRATES Cost of Goods Sold (Exclusive of Depreciation and Amortization) Cost of Goods and Service [Policy Text Block] 11. DEBT Debt Disclosure [Text Block] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount Accounts payable Accounts payable Accounts Payable, Current Operating Lease, Payments Operating Lease, Payments SARs [Member] Stock Appreciation Rights (SARs) [Member] Stock Appreciation Rights (SARs) [Member] Other comprehensive (loss) income before income tax effect Other Comprehensive Income (Loss), before Tax Foreign (all other countries) Current Foreign Tax Expense (Benefit) Goodwill [Roll Forward] Goodwill [Roll Forward] Restructuring Plan [Domain] Restructuring Plan [Domain] 20. COMMITMENTS AND CONTINGENCIES Commitments and Contingencies Disclosure [Text Block] Derivative Assets (Liabilities), at Fair Value, Net Derivative asset (liability) Derivative Assets (Liabilities), at Fair Value, Net Other long–term assets Other Assets, Noncurrent [Abstract] Outstanding, beginning of period (Indian Rupees/USD per share) Outstanding, end of period (Indian Rupees/USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Exercise Price Weighted average price at which grantees can acquire the shares reserved for issuance under the share-based compensation plan. Outflows from settlement of derivative instruments, net Payments for (Proceeds from) Derivative Instrument, Investing Activities Non-GAAP Measure Description Non-GAAP Measure Description [Text Block] Weighted Average Remaining Contractual Term, Outstanding Weighted Average Remaining Contractual Term, Outstanding Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Remaining Contractual Terms Derivative [Table] Derivative [Table] Entity Small Business Entity Small Business Income Tax Disclosure [Abstract] Income Tax Disclosure [Abstract] Income tax penalties and interest expense Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Schedule of changes in projected benefit obligations Schedule of Changes in Projected Benefit Obligations [Table Text Block] Brazilian Tax Authorities and Other Third Parties Brazilian Tax Authorities and Other Third Parties [Member] Brazilian Tax Authorities and Other Third Parties [Member] Hong Kong HONG KONG State tax expense, net Current State and Local Tax Expense (Benefit) Document Transition Report Document Transition Report Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible List] Operating Lease, Right-of-Use Asset, Statement of Financial Position [Extensible Enumeration] Midwest Premium ("MWP") Contracts Midwest Premium ("MWP") Contracts [Member] Midwest Premium ("MWP") Contracts Supplier Finance Program, Obligation [Roll Forward] Supplier Finance Program, Obligation [Roll Forward] Total minimum lease payments Finance Lease, Liability, to be Paid Underlying Securities Award Underlying Securities Amount Other Machinery and Equipment Other Machinery and Equipment [Member] Equity Component [Domain] Equity Component [Domain] Document Period End Date Document Period End Date 19. INCOME TAXES Income Tax Disclosure [Text Block] Contribution for financing of social security, tax credit Contribution For Financing of Social Security, Tax Credit Contribution For Financing of Social Security, Tax Credit Proceeds from lines of credit Proceeds from Lines of Credit United Kingdom UNITED KINGDOM Awards Close in Time to MNPI Disclosures, Table Awards Close in Time to MNPI Disclosures [Table Text Block] Exchange remeasurement of deferred income taxes Income Tax Reconciliation, Canadian Statutory Income Tax Rate, Exchange Remeasurement of Deferred Income Taxes The portion of the difference, between total income tax expense or benefit as reported in the Income Statement for the year/accounting period and the expected income tax expense or benefit computed by applying the Canadian statutory income tax rates to pretax income from continuing operations, that is attributable to exchange remeasurement of deferred income taxes. Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible List] Operating Lease, Liability, Noncurrent, Statement of Financial Position [Extensible Enumeration] Total equity Balance Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Equity, Including Portion Attributable to Noncontrolling Interest Sierre flood losses, net of recoveries Gain (Loss) From Insurance Settlement Gain (Loss) From Insurance Settlement Document Type Document Type Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Outstanding, beginning of period (shares) Outstanding, end of period (shares) SARs outstanding (in shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding, Number Name Outstanding Recovery, Individual Name Loss Contingencies [Table] Loss Contingencies [Table] Accrued expenses and other current liabilities Accrued Expenses and Other Current Liabilities [Abstract] Accrued Expenses and Other Current Liabilities [Abstract] Products and Services [Axis] Product and Service [Axis] Accounts receivable, net Accounts receivable, net — third parties Accounts and Other Receivables, Net, Current Triggering Event [Axis] Triggering Event [Axis] Triggering Event Income before income tax provision Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion Derivative Instruments, Gain (Loss) Reclassified from Accumulated OCI into Income, Effective Portion Net sales Revenue from Contract with Customer, Excluding Assessed Tax Total current assets Assets, Current Assets, Current Range [Axis] Statistical Measurement [Axis] Settlement liabilities Loss Contingency Accrual Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Disposal Group Name [Axis] Disposal Group Name [Axis] France FRANCE ABL Revolver ABL Revolver [Member] ABL Revolver [Member] Peer Group Issuers, Footnote Peer Group Issuers, Footnote [Text Block] From 2015 to 2017 From 2015 to 2017 [Member] From 2015 to 2017 Reconciliation from income from reportable segments to net income attributable to out common shareholder Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Table Text Block] Current liabilities: Liabilities, Current [Abstract] Summary of gains (losses) associated with the change in the fair value derivative instruments recognized in "Other (income) expense, net" Derivative Instruments, Gain (Loss) [Table Text Block] Trade accounts receivable Accounts Receivable, Fair Value Disclosure Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Line of credit Long-Term Line of Credit Schedule of Related Party Transactions, by Related Party [Table] Related Party Transaction [Table] Accelerated depreciation Restructuring and Related Cost, Accelerated Depreciation Schedule of assumptions used Defined Benefit Plan, Assumptions [Table Text Block] Sale of stock, number of shares issued (in shares) Sale of Stock, Number of Shares Issued in Transaction Consolidation Items [Domain] Consolidation Items [Domain] Auditor Location Auditor Location Fairmont Pension Plan Fairmont Pension Plan [Member] Fairmont Pension Plan 8. INVESTMENT IN AND ADVANCES TO NON-CONSOLIDATED AFFILIATES AND RELATED PARTY TRANSACTIONS Equity Method Investments and Joint Ventures Disclosure [Text Block] Actuarial gains Defined Benefit Plan, Benefit Obligation, Actuarial Gain (Loss) Amendments Defined Benefit Plan, Benefit Obligation, Increase (Decrease) for Plan Amendment Members' contributions Defined Benefit Plan, Benefit Obligation, Contributions by Plan Participant Minimum amount for excess availability Debt Instrument, Covenant, Minimum Amount for Excess Availability under ABL Revolver Debt Instrument, Covenant, Minimum Amount for Excess Availability under ABL Revolver Less: interest Lessee, Operating Lease, Liability, Undiscounted Excess Amount Total Taxes Paid Income Taxes Paid, Net Other Effective Income Tax Rate Reconciliation, Nondeductible Expense, Other, Percent Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Projected Benefit Obligation 2028 Finite-Lived Intangible Asset, Expected Amortization, Year Two Postemployment benefits liability, noncurrent Postemployment Benefits Liability, Noncurrent September and November Oswego fires losses, net of recoveries Loss from Catastrophes Long-term debt, principal Long-Term Debt, Gross Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer China Loan, due November 2027 China Loan, due November 2027 [Member] China Loan, due November 2027 5. PROPERTY, PLANT AND EQUIPMENT Property, Plant and Equipment Disclosure [Text Block] Total minimum lease payments Lessee, Operating Lease, Liability, to be Paid Seven-year Secured Term Loan Credit Facility Seven-year Secured Term Loan Credit Facility [Member] Seven-year Secured Term Loan Credit Facility [Member] Tradenames Trade Names [Member] Net change in pension and other benefits Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax Korea KOREA, REPUBLIC OF Intersegment eliminations Intersegment Eliminations [Member] Expiration Date Trading Arrangement Expiration Date Ownership in VIE Variable Interest Entity, Qualitative or Quantitative Information, Ownership Percentage Equipment under Capital Lease Obligations Assets Held under Capital Leases [Member] Other liabilities Increase (Decrease) in Other Operating Liabilities 2031 Finite-Lived Intangible Asset, Expected Amortization, Year Five Provisions not currently deductible for tax purposes Deferred Tax Assets, Tax Deferred Expense, Reserves and Accruals, Other Property, plant and equipment, net Property, plant and equipment, net Long-lived assets Property, Plant and Equipment, Net Forfeited/Cancelled (Indian Rupees/USD per share) Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Weighted average price of equity instruments other than options that were either forfeited or expired. Principal payments of long-term and short-term borrowings Repayments of Debt and Lease Obligation Restructuring charges Expenses recognized Restructuring Charges 6.375% Senior Notes due August 2033 6.375% Senior Notes due August 2033 [Member] 6.375% Senior Notes due August 2033 Compensation Actually Paid vs. Net Income Compensation Actually Paid vs. Net Income [Text Block] Accounts receivable Increase (Decrease) in Accounts Receivable Schedule of Restructuring and Related Costs [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] Consolidated Entities [Domain] Consolidated Entities [Domain] Canada Statutory Tax Rate Effective Income Tax Rate Reconciliation at Federal Statutory Income Tax Rate, Amount Foreign tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Percent (Gain) loss on sale or disposal of assets, net (Gain) loss on sale or disposal of assets, net (Gain) loss on sale or disposal of assets, net Gain (Loss) on Disposition of Property Plant Equipment Deferred income tax assets: Deferred Tax Assets, Gross [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract] Executive Category: Executive Category [Axis] If Additional Term Loans to be Issued If Additional Term Loans to be Issued [Member] If Additional Term Loans to be Issued State and Local Income Taxes, net Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Percent Finance Lease, Liability, Current Finance Lease, Liability, Current Defined Benefit Plan, Accumulated Benefit Obligation Defined Benefit Plan, Accumulated Benefit Obligation Interest expense and amortization of debt issuance costs Interest expense and amortization of debt issuance costs Interest Expense, Operating and Nonoperating Current Fiscal Year End Date Current Fiscal Year End Date Health care cost trend rate assumed Defined Benefit Plan, Health Care Cost Trend Rate Assumed, Next Fiscal Year Technology and software Technology-Based Intangible Assets [Member] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Activity in the allowance for doubtful accounts Activity in the Allowance for Doubtful Accounts [Table Text Block] Activity in the Allowance for Doubtful Accounts [Table Text Block] Number of operating plants Number of Operating Facilities Number of operating facilities Schedule of accounts receivable Schedule of Accounts, Notes, Loans and Financing Receivable [Table Text Block] Grant Date Fair Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value [Abstract] Professional fees Professional Fees Derivative Liability Derivative Liability Derivative Liability Granted Share-based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other than Options, Granted, Aggregate Intrinsic Value Share-based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other than Options, Granted, Aggregate Intrinsic Value Other Other Noninterest Expense Equity Awards Adjustments, Excluding Value Reported in Compensation Table Equity Awards Adjustments, Excluding Value Reported in the Compensation Table [Member] Prior service credit Other Comprehensive (Income) Loss, Defined Benefit Plan, Prior Service Cost (Credit), Reclassification Adjustment from AOCI, before Tax Italy ITALY Legislative changes including enacted tax rates Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Percent Derivative assets and liabilities measured and recognized at fair value on a recurring basis classified under the appropriate level of the fair value hierarchy Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Beginning balance of unrecognized tax benefits Ending Balance of unrecognized tax benefits Unrecognized tax benefits Unrecognized Tax Benefits 2 years Long-Term Debt, Maturity, Year Two 9. 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] Schedule of defined benefit plan amounts recognized in other comprehensive income (loss) Schedule of Defined Benefit Plan Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] 1. BUSINESS AND SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES Basis of Presentation and Significant Accounting Policies [Text Block] Property, Plant and Equipment, Type [Domain] Long-Lived Tangible Asset [Domain] Cost of goods sold (exclusive of depreciation and amortization) Cost of Goods and Service, Excluding Depreciation, Depletion, and Amortization Disposal Group Classification [Domain] Disposal Group Classification [Domain] Derivative, Nonmonetary Notional Amount Derivative, Nonmonetary Notional Amount Derivative, Nonmonetary Notional Amount Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Supplier invoices Confirmed obligations outstanding at the beginning of the year Confirmed obligations outstanding at the end of the year Supplier Finance Program, Obligation 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 Amortization of debt issuance costs and carrying value adjustments Amortization of Debt Issuance Costs Entity Tax Identification Number Entity Tax Identification Number Europe Premium Duty Paid ("ECDP") Contracts Europe Premium Duty Paid ("ECDP") Contracts [Member] Europe Premium Duty Paid ("ECDP") Contracts Foreign Exchange and Other Accounts Receivable, Allowance for Credit Loss, Period Increase (Decrease) Tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent Schedule of variable interest entity Schedule of Variable Interest Entities [Table Text Block] Actuarial losses (gains) Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans, Actuarial Loss, Before Tax Other Comprehensive Income Loss Amortization Pension And Other Postretirement Benefit Plans, Actuarial Loss, Before Tax Common stock, shares issued (in shares) Common Stock, Shares, Issued Funded pension plans Defined Contribution Plan Employers Contribution To Funded Pension Plan Defined contribution plan employers contribution to funded pension plan. 4 years Long-Term Debt, Maturity, Year Four Operating Lease, Weighted Average Remaining Lease Term Operating Lease, Weighted Average Remaining Lease Term GOODWILL AND INTANGIBLE ASSETS Goodwill and Intangible Assets Disclosure [Text Block] 4.750% Senior Notes, due January 2030 Senior Notes due January 2030 [Member] Senior Notes due January 2030 Currency (gains) losses included in other income expense Currency Gains Losses Included In Other Income Expense [Abstract] Currency gains losses included in other income expense. Entity Public Float Entity Public Float Confirmed invoices paid during the year Supplier Finance Program, Obligation, Settlement Schedule of goodwill Schedule of Goodwill [Table Text Block] Trading Arrangement: Trading Arrangement [Axis] Fair value of derivative instruments Derivative Assets, Current Derivative Asset, Current Total Shareholder Return Amount Total Shareholder Return Amount Nontaxable dividends Effective Income Tax Rate Reconciliation, Deduction, Dividends, Amount Loss Contingencies [Line Items] Loss Contingencies [Line Items] Pension plans with accumulated benefit obligations in excess of plan assets, fair value of plan assets Pension Plans with Projected Benefit Obligations Less than Plan Assets, Fair Value of Plan Assets Pension Plans with Projected Benefit Obligations Less than Plan Assets, Fair Value of Plan Assets Net actuarial gains (losses) Defined Benefit Plan, Accumulated Other Comprehensive Income (Loss), Gain (Loss), before Tax Restructuring and impairment, net Restructuring and impairment, net Restructuring Costs and Asset Impairment Charges Corporate, Non-Segment Segment Reporting, Reconciling Item, Corporate Nonsegment [Member] Foreign Tax Income Tax Paid, Foreign, after Refund Received Other Pension Plan [Member] Other Pension Plan [Member] Savings and defined contribution pension plans Defined Contribution Plan Employers Contribution To Savings And Defined Contribution Pension Plan Defined contribution plan employers contribution to savings and defined contribution pension plan. Liabilities, Noncurrent Liabilities, Noncurrent Energy contracts Energy Related Derivative [Member] Accrued capital expenditures as of March 31 Capital Expenditures Incurred but Not yet Paid Maximum borrowing capacity Line of Credit Facility, Maximum Borrowing Capacity SEC Schedule, 12-09, Reserve, Environmental Cost SEC Schedule, 12-09, Reserve, Environmental Cost [Member] Plan Asset Categories [Domain] Defined Benefit Plan, Plan Assets, Category [Domain] Unamortized Carrying Value Adjustments, total debt Debt Instrument, Unamortized Carrying Value Adjustment Unamortized carrying value adjustment of debt instrument (including both long-term debt and capital lease obligations). Financing Costs Interest Expense, Policy [Policy Text Block] Other current liabilities Other Liabilities, Current Members' contributions Defined Benefit Plan, Plan Assets, Contributions by Plan Participant 14. CURRENCY LOSSES (GAINS) Foreign Currency Disclosure [Text Block] Weighted average assumptions used to determine net periodic benefit cost, Discount rate Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Discount Rate Foreign Currency [Abstract] Foreign Currency [Abstract] Accrued postretirement benefits Accrued postretirement benefits Liability, Defined Benefit Plan, Noncurrent Statement [Line Items] Statement [Line Items] Extinguishment of debt Extinguishment of Debt, Amount Rule 10b5-1 Arrangement Adopted Rule 10b5-1 Arrangement Adopted [Flag] Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalent Repairs and clean-up costs Repairs And Clean-Up Costs Repairs And Clean-Up Costs Common Stock Common Stock Common Stock [Member] Amount of Gain (Loss) Recognized in Other expenses (income), net (Ineffective and Excluded Portion) Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing Derivative Instruments, Gain (Loss) Recognized in Income, Ineffective Portion and Amount Excluded from Effectiveness Testing Loss (gain) on unrealized derivatives and other realized derivatives in investing activities, net Unrealized Gain (Loss) on Investments Foreign currency translation Asset Retirement Obligation, Foreign Currency Translation Gain (Loss) Range [Domain] Statistical Measurement [Domain] Maintaining Minimum Fixed Charge Ratio Maintaining Minimum Fixed Charge Ratio [Member] Maintaining Minimum Fixed Charge Ratio Thereafter Lessee, Operating Lease, Liability, to be Paid, after Year Five Summary of notional amount Schedule of Notional Amounts of Outstanding Derivative Positions [Table Text Block] Minimum fixed charge coverage ratio Debt Instrument, Covenant, Maximum Fixed Charge Coverage Ratio Maximum fixed charge coverage ratio required under certain terms of debt covenant. Operating Lease, Liability, Current, Statement of Financial Position [Extensible List] Operating Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Interest rate swap contracts Interest Rate Swap [Member] Foreign currency translation and other Restructuring Reserve, Translation and Other Adjustment Equity in net loss (income) of non-consolidated affiliates Equity in net loss (income) of non-consolidated affiliates Income (Loss) from Equity Method Investments Leases [Abstract] Additions based on tax positions of prior years(1) Unrecognized Tax Benefits, Increase Resulting from Prior Period Tax Positions Intangible Asset, Acquired, Finite-Lived [Line Items] Intangible Asset, Acquired, Finite-Lived [Line Items] Provision at the Canadian statutory rate Income Tax Reconciliation, Income Tax Expense (Benefit), at Canadian Statutory Income Tax Rate The amount of income tax expense or benefit for the period computed by applying the Canadian statutory tax rates to pretax income from continuing operations. Accounts payable Increase (Decrease) in Accounts Payable Interest income Interest Income (Expense), Nonoperating Type of Restructuring [Domain] Type of Restructuring [Domain] Valuation Allowance Additions Valuation Allowance Additions Valuation Allowance Additions Trading Arrangements, by Individual Trading Arrangements, by Individual [Table] Weighted Average Remaining Contractual Term, Granted Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Remaining Contractual Terms Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Remaining Contractual Terms Foreign exchange Unrecognized Tax Benefits, Net Changes Resulting from Foreign Currency Translation Unrecognized Tax Benefits, Net Changes Resulting from Foreign Currency Translation Pension plans with accumulated benefit obligations in excess of plan assets, fair value of plan assets Defined Benefit Plan, Plan with Accumulated Benefit Obligation in Excess of Plan Assets, Plan Assets Operating and Finance Lease Right of Use Assets Operating and Finance Lease Right of Use Assets Operating and Finance Lease Right of Use Assets Changes in unrecognized tax benefits Effective Income Tax Rate Reconciliation, Tax Contingency, Percent Assets and Liabilities Held for Sale Assets and Liabilities Held-for-sale [Policy Text Block] Assets and Liabilities Held-for-sale [Policy Text Block] Cost of Goods Sold Cost of Goods and Service Benchmark [Member] Total deferred income tax assets Deferred Tax Assets, Gross Depreciation and amortization Depreciation and Amortization [Member] Depreciation and Amortization [Member] Weighted average assumptions used to determine benefit obligations, Discount rate Defined Benefit Plan, Assumptions Used Calculating Benefit Obligation, Discount Rate Other comprehensive (loss) income, net of tax Other Comprehensive Income (Loss), Net of Tax Selected segment financial information Schedule of Segment Reporting Information, by Segment [Table Text Block] Inventory Disclosure [Abstract] Inventory Disclosure [Abstract] Short–term borrowings Short-term borrowings Short-Term Debt Supplies Other Inventory, Supplies, Gross Metal forward contracts Metal forward contracts [Member] Metal forward contracts Consolidated EBIDTA, percent Benchmark Consolidated EBIDTA As Percent Benchmark Consolidated EBIDTA As Percent Other Defined Benefit Plan, Other Cost (Credit) Estimated fair value of certain financial instruments that are not recorded at fair value on a recurring basis Fair Value Measurements, Nonrecurring [Table Text Block] 2029 Finance Lease, Liability, to be Paid, Year Three Expected additional contribution to unfunded pension plan Additional Contributions To Unfunded Pension Plan Additional Contributions To Unfunded Pension Plan Additional contributions to unfunded pension plan. Award Timing MNPI Disclosure Award Timing MNPI Disclosure [Text Block] Research and Development Research and Development Expense, Policy [Policy Text Block] Proceeds from sales of assets, third party Proceeds from Sale of Productive Assets Cash and Cash Equivalents Cash and Cash Equivalents [Member] Fuel Fuel [Member] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Uncertain tax positions Income Tax Reconciliation, Canadian Statutory Income Tax Rate, Tax Contingencies The sum of the differences between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the Canadian statutory income tax rates to pretax income from continuing operations attributable to changes in all income tax contingencies, whether recorded or adjusted, during the period. Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Total compensation expense Share-Based Payment Arrangement, Expense China Loan, due December 2027 China Loan, due December 2027 [Member] China Loan, due December 2027 Hedging Designation [Domain] Hedging Designation [Domain] Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Finance Lease, Liability, Current, Statement of Financial Position [Extensible Enumeration] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill and Intangible Assets Disclosure [Abstract] Current assets: Assets, Current [Abstract] Metal contracts Metal Contracts [Member] Metal Contracts Total liabilities and equity Liabilities and Equity Liabilities and Equity Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Postretirement Benefit Plans Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Derivative Instruments, Gain (Loss) [Table] Derivative Instruments, Gain (Loss) [Table] 2025 Term Loan 2025 Term Loan [Member] 2025 Term Loan Other assets Other deferred tax assets Deferred Tax Assets, Other Schedule of Equity Method Investments [Table] Equity Method Investment [Table] Capital expenditures Segment, Expenditure, Addition to Long-Lived Assets Lessee, Operating Lease, Liability, Maturity Lessee, Operating Lease, Liability, to be Paid, Maturity [Table Text Block] Concentration Risk Type [Domain] Concentration Risk Type [Domain] Forward Contracts Forward Contracts [Member] Pay vs Performance Disclosure [Line Items] Present value of lease liabilities Operating Lease, Liability Schedule of lease information Schedule of lease information [Table Text Block] Schedule of lease information LIABILITIES Liabilities [Abstract] Summary of Valuation Allowance Summary of Valuation Allowance [Table Text Block] Financial Liabilities Fair Value Disclosure Financial Liabilities Fair Value Disclosure Other long–term liabilities Other Liabilities, Noncurrent Difference between carrying amount and underlying equity Equity Method Investment, Difference Between Carrying Amount and Underlying Equity Goodwill, impairment loss Goodwill, Impairment Loss Schedule of Variable Interest Entities [Table] Variable Interest Entity [Table] Schedule of amortization expense Intangible Asset Amortization Expense [Table Text Block] [Table Text Block] for Intangible Asset Amortization Expense [Table] Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Company Selected Measure Amount Company Selected Measure Amount Cash Cash Company contributions Defined Benefit Plan, Plan Assets, Contributions by Employer 2029 Lessee, Operating Lease, Liability, to be Paid, Year Three Debt issuance costs, gross Debt Issuance Costs, Gross Comprehensive (loss) income attributable to our common shareholder Comprehensive Income (Loss), Net of Tax, Attributable to Parent Proceeds (outflows) from investment in and advances to non-consolidated affiliates, net Payments For (Proceeds from) Advance To Affiliate Payments For (Proceeds from) Advance To Affiliate Disposal Group Name [Domain] Disposal Group Name [Domain] Name Measure Name Schedule of components of income before income taxes, domestic and foreign Schedule of Income before Income Tax, Domestic and Foreign [Table Text Block] Secured Debt Secured Debt [Member] Expected long-term rate of return on plan assets Weighted average assumptions used to determine net periodic benefit cost, Expected return on plan assets Defined Benefit Plan, Assumptions Used Calculating Net Periodic Benefit Cost, Expected Long-Term Rate of Return on Plan Assets Beverage packaging(1) Can Sales [Member] Can Sales [Member] Aggregate Intrinsic Value, Granted Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value1 Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Grants in Period, Grant Date Intrinsic Value1 Valuation Allowance Deductions Valuation Allowance Deductions Valuation Allowance Deductions Income Tax Details [Table] Income Tax Contingency [Table] Long-term debt, carrying value Long-Term Debt (Gains) losses on remeasurement of monetary assets and liabilities, net Gain (Loss) on Remeasurement of Monetary Assets and Liabilities, Net Gain (loss) on remeasurement of monetary assets and liabilities net. Total assets Total assets Assets 2027 Finite-Lived Intangible Asset, Expected Amortization, Year One Hindalco RSUs [Member] Hindalco RSUs [Member] Hindalco RSUs Quarterly amortization payments, percent Debt Instrument, Quarterly Amortization Payments, Percent Debt Instrument, Quarterly Amortization Payments, Percent Geographical [Domain] Geographical [Domain] Bank Loans, Due Through August 2027 Bank Loans, Due Through August 2027 [Member] Bank Loans, Due Through August 2027 Income Taxes Income Tax, Policy [Policy Text Block] OPERATING ACTIVITIES Cash Provided by (Used in) Operating Activity, Including Discontinued Operation [Abstract] Other segment items Segment Reporting, Other Segment Item, Amount Supplemental Disclosures: Additional Cash Flow Elements and Supplemental Cash Flow Information [Abstract] Concentration Risk Type [Axis] Concentration Risk Type [Axis] 4. INVENTORIES Inventory Disclosure [Text Block] Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] 2030 Finite-Lived Intangible Asset, Expected Amortization, Year Four Restructuring costs Restructuring Costs 2027 Finance Lease, Liability, to be Paid, Year One Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Right-of-Use Asset Obtained in Exchange for Operating Lease Liability Schedule of fair value of pension and postretirement plan assets table Schedule Of Fair Value Of Pension And Postretirement Plan Assets Table [Text Block] Schedule Of Fair Value Of Pension And Postretirement Plan Assets [Table Text Block] Level 2 [Member] Level 2 Instruments [Member] Fair Value, Inputs, Level 2 [Member] Document Financial Statement Error Correction Document Financial Statement Error Correction [Flag] State and Local Income Taxes, net Effective Income Tax Rate Reconciliation, State and Local Income Taxes, Amount Investment in and advances to non–consolidated affiliates Equity Method Investments Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] Related Parties Related Party [Member] Equity Method Investments Equity Method Investments [Member] Cash flow sales Cash flow sales [Member] Cash flow sales Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Defined Benefit Plan, Change in Fair Value of Plan Assets [Roll Forward] Summary of condensed results of operations of equity method affiliates Equity Method Investment, Summarized Financial Information, Income Statement [Table Text Block] Tabular disclosure of the entity's share of earnings (losses) of equity method investments. Schedule of components of income tax provision Schedule of Components of Income Tax Expense (Benefit) [Table Text Block] Plan Name [Axis] Plan Name [Axis] Property, Plant and Equipment Property, Plant and Equipment, Policy [Policy Text Block] PEO PEO [Member] Expense (income) items not subject to tax Income Tax Reconciliation, Canadian Statutory Income Tax Rate, Nondeductible Expense The sum of the differences between total income tax expense or benefit as reported in the Income Statement for the period and the expected income tax expense or benefit computed by applying the Canadian statutory income tax rates to pretax income from continuing operations attributable to nondeductible expenses under enacted tax laws. Employees Employee Severance [Member] Pre-tax income before equity in net loss (income) of non-consolidated affiliates Pre-tax income before equity in net loss (income) of non-consolidated affiliates Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Noncontrolling Interest Income Tax Paid, by Individual Jurisdiction [Line Items] Income Tax Paid, by Individual Jurisdiction [Line Items] United States UNITED STATES Changes in assets and liabilities including assets and liabilities held for sale: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity, Increase (Decrease) in Operating Capital [Abstract] Valuation Allowance Effective Income Tax Rate Reconciliation, Change in Deferred Tax Assets Valuation Allowance, Amount Volatility Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions, Expected Volatility Rate Retained Earnings Retained Earnings Retained Earnings [Member] Income Tax Authority [Axis] Income Tax Jurisdiction [Axis] Schedule of accrued liabilities Schedule of Accrued Liabilities [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Share-Based Payment Arrangement [Abstract] Cash, cash equivalents and restricted cash — beginning of period Cash, cash equivalents and restricted cash — end of period Cash, cash equivalents and restricted cash — end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Income Statement [Abstract] Income Statement [Abstract] Derivative Asset Derivative Asset Funded Plan [Member] Defined Benefit Plan, Funded Plan [Member] Revenue, Major Customer [Line Items] Revenue, Major Customer [Line Items] Facility Closing Facility Closing [Member] Taxes payable, current Taxes Payable, Current Derivative Liabilities, Noncurrent Derivative Liability, Noncurrent 2021 Term Loans 2021 Term Loans [Member] 2021 Term Loans Percent Income Tax Paid, by Individual Jurisdiction, Percent [Abstract] Income Tax Paid, by Individual Jurisdiction, Percent Principle payable Financing Receivable, Principle Payable Financing Receivable, Principle Payable Products and Services [Domain] Product and Service [Domain] Customer Concentration Risk Customer Concentration Risk [Member] Citi Facility Citi Facility [Member] Citi Facility Tax losses/benefit carryforwards, net Deferred Tax Assets, Operating Loss and Tax Credit Carryforwards Amount before allocation of valuation allowances of deferred tax asset attributable to deductible operating loss carryforwards and to other deductible tax credit carryforwards not separately disclosed. Purchase of tolling services from Alunorf Purchase Of Tolling Services Purchase of tolling services. Net income Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Restatement does not require Recovery Restatement Does Not Require Recovery [Text Block] Derivative, Notional Amount Derivative, Notional Amount Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Capital expenditures Payments to Acquire Other Productive Assets Imputed income Effective Income Tax Rate Reconciliation, Tax Exempt Income, Amount Other, net Other Nonoperating Income (Expense), Other Other Nonoperating Income (Expense), Other Income Tax Paid, by Individual Jurisdiction [Table] Income Tax Paid, by Individual Jurisdiction [Table] City Area Code City Area Code Award Timing, How MNPI Considered Award Timing, How MNPI Considered [Text Block] Capitalized interest costs Interest Costs Capitalized Natural Gas Swaps Natural Gas Swaps [Member] Natural gas swaps. Buildings Buildings and Improvements, Gross Net deferred income tax (assets) liabilities Deferred Tax Liabilities, Net Inventory valuation reserves Deferred Tax Liabilities, Inventory INVESTING ACTIVITIES Cash Provided by (Used in) Investing Activity, Including Discontinued Operation [Abstract] Long-lived assets and other intangible assets Long-Lived Assets Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Supplier [Axis] Supplier [Axis] Disposed of by Sale Disposal Group, Disposed of by Sale, Not Discontinued Operations [Member] Related Party Transactions [Abstract] Related Party Transactions [Abstract] 6.875% Senior Notes, due January 2030 6.875% Senior Notes, due January 2030 [Member] 6.875% Senior Notes, due January 2030 Amortization — losses (gains), net (gains (losses), net) Defined Benefit Plan, Amortization of Gain (Loss) Schedule of assets and liabilities related to operating and financing leases Schedule of assets and liabilities related to operating and financing leases [Table Text Block] Schedule of assets and liabilities related to operating and financing leases Selling, General and Administrative Expenses Selling, General and Administrative Expenses [Member] Cost of goods sold Cost of Sales [Member] Cash flow hedges Cash Flow Hedging [Member] Goodwill Goodwill Goodwill, Beginning Balance Goodwill, Ending Balance Goodwill Estimate of possible loss Loss Contingency, Estimate of Possible Loss Lease, Cost Lease, Cost [Table Text Block] Sierre flood Flood [Member] Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets Defined Benefit Plan, Pension Plan with Projected Benefit Obligation in Excess of Plan Assets, Plan Assets Domestic (Canada) Deferred Federal Income Tax Expense (Benefit) Assets held for sale Asset, Held-for-Sale, Not Part of Disposal Group, Current Reconciliation of Unrecognized Tax Benefits, Excluding Amounts Pertaining to Examined Tax Returns [Roll Forward] Unrecognized Tax Benefits [Roll Forward] Auditor Name Auditor Name Concentration Risk [Table] Concentration Risk [Table] Schedule of depreciation expense Schedule of depreciation expense [Table Text Block] Schedule of depreciation expense [Table Text Block] Aluminum Forward Sales Contracts Aluminum Foward Sales Contracts [Member] Aluminum foward sales contracts Assumptions used in estimating fair value of SARs Share-Based Compensation Arrangement by Share-Based Payment Award, Fair Value Assumptions and Methodology [Abstract] Operating loss carryforwards, valuation allowance Operating Loss Carryforwards, Valuation Allowance Restructuring Cost and Reserve [Line Items] Restructuring Cost and Reserve [Line Items] Accumulated Impairment Goodwill, Impaired, Accumulated Impairment Loss Other Performance Measure, Amount Other Performance Measure, Amount Currency translation adjustment, included in other comprehensive (loss) income Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Gain (Loss) Arising During Period, Net of Tax Debt issuance costs Payments of Debt Issuance Costs Pension and Postretirement Benefits Pension and Other Postretirement Plans, Policy [Policy Text Block] Related Party [Domain] Related and Nonrelated Parties [Domain] Amount Income Tax Expense (Benefit), Effective Income Tax Rate Reconciliation, Amount [Abstract] Real Estate [Member] Real Estate [Member] Other Current Liabilities Other Current Liabilities [Member] Net increase (decrease) in cash and cash equivalents and restricted cash Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Excluding Exchange Rate Effect, Including Discontinued Operation Withholding tax expense Effective Income Tax Rate Reconciliation, Withholding Tax Expense, Amount Effective Income Tax Rate Reconciliation, Withholding Tax Expense, Amount Derivative Instrument Risk [Axis] Derivative Instrument [Axis] Benefits paid Benefits paid Defined Benefit Plan, Plan Assets, Benefits Paid Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] 9. LEASES Lessee, Finance Leases [Text Block] Additional paid–in capital Additional Paid in Capital, Common Stock Other Restructuring [Member] Other Restructuring [Member] Defined Benefit Plan, Plan Assets, Payment for Settlement Settlements Defined Benefit Plan, Plan Assets, Payment for Settlement Net cash used in investing activities Cash Provided by (Used in) Investing Activity, Including Discontinued Operation 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] Derivative Asset, Noncurrent Derivative Asset, Noncurrent Gain on sale of business Gain on sale of business Gain (Loss) on Disposition of Business Interest paid Interest Paid, Excluding Capitalized Interest, Operating Activity Document Fiscal Year Focus Document Fiscal Year Focus Right of use assets Operating Lease, Right-of-Use Asset Accrued compensation and benefits Accrued Employee Benefits, Current Income tax credits and adjustments Income Tax Credits and Adjustments Effective Income Tax Rate Reconciliation, Percent Effective tax rate Effective Income Tax Rate Reconciliation, Percent Reductions based on tax positions of prior years (2) Unrecognized Tax Benefits, Decrease Resulting from Prior Period Tax Positions Operating Lease, Cost Operating Lease, Cost Equity Method Investment, Nonconsolidated Investee [Axis] Equity Method Investment, Nonconsolidated Investee [Axis] Deferred income tax liabilities Deferred Tax and Other Liabilities, Noncurrent Accounts Receivable Accounts and Nontrade Receivable [Text Block] Plan Name [Domain] Plan Name [Domain] Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Share-Based Payment Arrangement, Nonvested Award, Cost Not yet Recognized, Period for Recognition Exercised (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Exercises in Period Bank Loan Obligations Bank Loan Obligations [Member] Valuation allowance, beginning of period Valuation allowance, end of period Less: valuation allowance Deferred tax assets, valuation allowance Deferred Tax Assets, Valuation Allowance Equity [Abstract] Equity [Abstract] North America North America [Member] Buildings Building [Member] Derivative Instruments Derivatives, Policy [Policy Text Block] 21. SEGMENT, GEOGRAPHICAL AREA, MAJOR CUSTOMER AND MAJOR SUPPLIER INFORMATION Segment Reporting Disclosure [Text Block] Schedule of Goodwill [Table] Goodwill [Table] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Derivatives not designated as hedging instruments: Not Designated as Hedging Instrument [Member] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Schedule of Acquired Finite-Lived Intangible Asset by Major Class [Table] Fair value of plan assets at beginning of period Fair value of plan assets at end of period Defined Benefit Plan, Fair Value of Plan Assets Pension plan assets Defined Benefit Plan, Plan Assets, Amount Monetary exchange gains, net Deferred Tax Liabilities, Monetary Exchange Gains, net Amount of deferred tax liability attributable to taxable temporary differences from net monetary exchange gains Domestic (Canada) Current Federal Tax Expense (Benefit) Debt and Lease Obligation Debt and Lease Obligation New Accounting Pronouncements or Change in Accounting Principle [Line Items] New Accounting Pronouncements or Change in Accounting Principle [Line Items] Increase (Decrease) in Stockholder's Equity [Roll Forward] Increase (Decrease) in AOCI [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Components of net periodic benefit cost for all significant postretirement benefit plans Schedule of Net Benefit Costs [Table Text Block] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] 16. ACCUMULATED OTHER COMPREHENSIVE LOSS Comprehensive Income (Loss) Note [Text Block] Change in valuation allowances Income Tax Reconciliation, Canadian Statutory Income Tax Rate, Change in Deferred Tax Assets Valuation Allowance The portion of the difference between total income tax expense or benefit as reported in the Income Statement and the expected income tax expense or benefit computed by applying the Canadian statutory income tax rates to pretax income from continuing operations attributable to changes in the valuation allowance for deferred tax assets in the period. Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value, Recurring and Nonrecurring [Table] Amortization expense related to intangible assets included in depreciation and amortization Amortization of Intangible Assets Selling, general and administrative expenses Selling, General and Administrative Expense Deferred income tax assets Deferred Income Tax Assets, Net Schedule of accumulated other comprehensive income (loss) Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Depreciation and amortization Depreciation and amortization Depreciation and amortization Depreciation, Depletion and Amortization Gain (loss) due to settlement Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Gain (Loss) Due to Settlement 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 Credit Facility Revolving Credit Facility [Member] Tax rate differential Effective Income Tax Rate Reconciliation, Foreign Income Tax Rate Differential, Amount Present value of lease liabilities Finance Lease, Liability Arrangement Duration Trading Arrangement Duration Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Derivative, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration] Segments [Axis] Segments [Axis] Currency losses, net Currency Gains (Losses) Included in Other Income Expense, Net Currency gains (losses) included in other income expense, net. Local Phone Number Local Phone Number Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Accounts receivable — third parties Accounts Receivable, before Allowance for Credit Loss, Current Total Taxes Paid Income Taxes Paid, Net, Percent Income Taxes Paid, Net, Percent Granted (Indian Rupees/USD per share) Share-based Compensation Arrangements by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Exercise Price Weighted average price at which grantees can acquire the shares reserved for issuance on stock options awarded. Europe Europe [Member] Other Payment for (Proceeds from) Other Investing Activity Thereafter Long-Term Debt, Maturity, after Year Five 12. SHARE-BASED COMPENSATION Share-Based Payment Arrangement [Text Block] South America South America [Member] ASSETS Assets [Abstract] Credit Facility [Axis] Credit Facility [Axis] Underlying Security Market Price Change Underlying Security Market Price Change, Percent Supplier Finance Program Supplier Finance Program [Table Text Block] Debt Instrument [Axis] Debt Instrument [Axis] Forfeited/Cancelled (Indian Rupees per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Forfeitures, Weighted Average Grant Date Fair Value 13. POSTRETIREMENT BENEFIT PLANS Retirement Benefits [Text Block] Loss on extinguishment of debt, net Loss on extinguishment of debt, net Gain (Loss) on Extinguishment of Debt Credit Facility [Domain] Credit Facility [Domain] Shareholder's equity: Equity, Attributable to Parent [Abstract] Fair value of derivative instruments Derivative Liabilities, Current Derivative Liability, Current Award vesting percentage Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Rights, Percentage Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration] Environmental Loss Contingency, Current, Statement of Financial Position [Extensible Enumeration] Net sales – intersegment Sales Revenue, Intersegment [Member] Sales Revenue, Intersegment [Member] Non-cash charges related to Oswego fires Non-Cash Charges Related To Catastrophic Events1 Non-Cash Charges Related To Catastrophic Events1 Net operating loss carryforwards Operating Loss Carryforward, tax effected Operating Loss Carryforward, tax effected Interest rate Debt Instrument, Interest Rate, Stated Percentage Investment, Name [Axis] Investment, Name [Axis] Net sales by value stream Revenue from External Customers by Products and Services [Table Text Block] Operating Lease, Liability, Noncurrent Operating Lease, Liability, Noncurrent Entity Voluntary Filers Entity Voluntary Filers Reconciliation of income from reportable segments to net income attributable to common shareholder Reconciliation of Operating Profit (Loss) from Segments to Consolidated [Abstract] Accrual for Environmental Loss Contingencies [Abstract] Accrual for Environmental Loss Contingencies [Abstract] Land and property rights Land Property, Plant and Equipment [Abstract] Property, Plant and Equipment [Abstract] Entity Registrant Name Entity Registrant Name Expected reclassification of gains (losses) from AOCI to earnings Cash Flow Hedge Gain (Loss) to be Reclassified within 12 Months Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Increase (decrease) for taxes on income (loss) resulting from: Increase Decrease For Taxes On Income Loss [Abstract] Increase (decrease) for taxes on income (loss) resulting. Net periodic benefit cost Non-operating net periodic benefit cost Defined Benefit Plan, Net Periodic Benefit Cost (Credit) Currency losses (gains) Defined Benefit Plan, Benefit Obligation, Foreign Currency Translation Gain (Loss) Supplier Finance Program, Obligation, Statement of Financial Position [Extensible Enumeration] Supplier Finance Program, Obligation, Statement of Financial Position [Extensible Enumeration] Assets, Fair Value Disclosure Assets, Fair Value Disclosure Granted (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Granted Finance lease, ROU assets Finance Lease, Right-of-Use Asset, before Accumulated Amortization Number of operating segments Number of Operating Segments Contributions to employee benefit plans Defined Contribution Plan Employers Contribution [Abstract] Defined contribution plan employers contribution. Aggregate Intrinsic Value, Outstanding Aggregate Intrinsic Value, Outstanding Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value, Outstanding Realized losses (gains) on change in fair value of derivative instruments, net Gain Loss On Change In Fair Value Of Other Realized Derivative Instruments Net (Gain) loss on change in fair value of other realized derivative instruments, net. Schedule of debt Schedule of Debt [Table Text Block] Machinery and Equipment Machinery and Equipment [Member] Interest cost Defined Benefit Plan, Interest Cost Granted (Indian Rupees 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 Party [Axis] Related and Nonrelated Parties [Axis] Tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Percent [Abstract] Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Exercise Price [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Outstanding, Weighted Average Exercise Price Other Long-term Liabilities Other Noncurrent Liabilities [Member] Restatement Determination Date: Restatement Determination Date [Axis] Curtailments, settlements, and special termination benefits Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Curtailment Gain (Loss) Arising During Period, before Tax Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Curtailment Gain (Loss) Arising During Period, before Tax Foreign (all other countries) Deferred Foreign Income Tax Expense (Benefit) Accumulated Other Comprehensive Income (Loss) [Table] Accumulated Other Comprehensive Income (Loss) [Table] Summary of restructuring reserve activity Restructuring and Related Costs [Table Text Block] Total Defined Benefit Plan, Expected Future Benefit Payment Defined Benefit Plan, Expected Future Benefit Payment Net actuarial gains (losses) Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), after Reclassification Adjustment, before Tax Amounts reclassified from accumulated other comprehensive loss, net Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Number of plants with recycling operations Number of Plants with Recycling Operations Number of plants with recycling operations Legislative changes including enacted tax rates Effective Income Tax Rate Reconciliation, Change in Enacted Tax Rate, Amount Name Trading Arrangement, Individual Name Schedule of changes in fair value of plan assets Schedule of Changes in Fair Value of Plan Assets [Table Text Block] Net change in fair value of effective portion of cash flow hedges Other Comprehensive Income (Loss), Cash Flow Hedge, Gain (Loss), after Reclassification, before Tax Duffel Duffel [Member] Duffel Principal amount Debt Instrument, Face Amount RSUs activity and SARs activity under LTIP Share-Based Payment Arrangement, Activity [Table Text Block] Short-term debt, terms Short-Term Debt, Terms Tax on change in pension and other benefits Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, Tax Statement of Comprehensive Income [Abstract] Statement of Comprehensive Income [Abstract] Name Awards Close in Time to MNPI Disclosures, Individual Name 10. ACCRUED EXPENSES AND OTHER CURRENT LIABILITIES Accounts Payable, Accrued Liabilities, and Other Liabilities Disclosure, Current [Text Block] Outstanding, beginning of period (Indian Rupees per share) Outstanding, end of period (Indian Rupees per share) Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Cash payments Payments for Restructuring Restricted cash (included in other long–term assets) Restricted Cash, Noncurrent Restructuring Type [Axis] Restructuring Type [Axis] Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Number of Shares, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Exercisable The number of equity-based payment instruments, excluding stock (or unit) options, that validly exist and are outstanding and exercisable at the balance sheet date. ICFR Auditor Attestation Flag ICFR Auditor Attestation Flag Debt covenant, senior net leverage ratio Debt Instrument, Covenant, Senior Net Leverage Ratio Debt Instrument, Covenant, Senior Net Leverage Ratio Net sales to largest customers, as a percentage of total net sales Schedule of Revenue by Major Customers by Reporting Segments [Table Text Block] Finance Lease, Liability, Fiscal Year Maturity Finance Lease, Liability, to be Paid, Maturity [Table Text Block] Fixed Income [Member] Fixed Income Funds [Member] Litigation Case [Axis] Litigation Case [Axis] Environmental Remediation Contingency [Domain] Environmental Remediation Contingency [Domain] Auditor Firm ID Auditor Firm ID Nontaxable dividends Effective Income Tax Rate Reconciliation, Deduction, Dividend, Percent Segments [Domain] Segments [Domain] Income Statement Location [Axis] Statement of Income Location, Balance [Axis] Foreign (all other countries) Income (Loss) from Continuing Operations before Income Taxes, Foreign Short-term borrowings Short-Term Debt [Member] Assets, Noncurrent Assets, Noncurrent Remaining borrowing capacity Line of Credit Facility, Remaining Borrowing Capacity Fair Value Hierarchy [Domain] Fair Value Hierarchy and NAV [Domain] Benefit obligation at beginning of period Benefit obligation at end of period Benefit obligation of unfunded plans Defined Benefit Plan, Benefit Obligation Defined Benefit Plan, Benefit Obligation Balance Sheet Location [Domain] Statement of Financial Position Location, Balance [Domain] Inventories Increase (Decrease) in Inventories Accrual for environmental loss contingencies, current Accrued Environmental Loss Contingencies, Current Excess costs to fulfill customer contracts Additional Freight Costs Additional Freight Costs Equity contribution from our common shareholder (in shares) Equity, Increase From Contribution, Shares Equity, Increase From Contribution, Shares Assets Derivative Asset [Abstract] Accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Noncontrolling Interests in Consolidated Affiliates Consolidation, Subsidiaries or Other Investments, Consolidated Entities, Policy [Policy Text Block] Line of credit facility, potential additional borrowing capacity Line of Credit Facility, Potential Additional Borrowing Capacity Amount of potential additional borrowing capacity under the credit facility. Revenue Recognition Revenue [Policy Text Block] Senior Notes Senior Notes [Member] Investment In and Advances To Non-Consolidated Affiliates and Related Party Transactions [Abstract] Investment In and Advances To Non-Consolidated Affiliates and Related Party Transactions [Abstract] Investment In and Advances To Non-Consolidated Affiliates and Related Party Transactions. 3.875% Senior Notes, due August 2031 3.875% Senior Notes, due August 2031 [Member] 3.875% Senior Notes, due August 2031 All Executive Categories All Executive Categories [Member] Contributions to equity method investee Contributions To Equity Method Investee Contributions To Equity Method Investee Schedule of deferred tax assets and liabilities Schedule of Deferred Tax Assets and Liabilities [Table Text Block] Schedule of accumulated benefit obligations in excess of fair value of plan assets Defined Benefit Plan, Plan with Projected Benefit Obligation in Excess of Plan Assets [Table Text Block] Common stock, no par value; Unlimited number of shares authorized; 606,333,333 and 600,000,000 shares issued and outstanding as of March 31, 2026 and March 31, 2025, respectively Common Stock, Value, Issued Finance lease, right-of-use asset Finance Lease, Right-of-Use Asset, after Accumulated Amortization Unrealized (gains) losses on change in fair value of derivative instruments, net Unrealized (losses) gains on change in fair value of derivative instruments, net Change in Unrealized Gain (Loss) on Fair Value Hedging Instruments ABL Facility ABL Facility [Member] ABL Facility. China Loan, Due September 2027 China Loan, Due September 2027 [Member] China Loan, Due September 2027 Commitments and contingencies Commitments and Contingencies Investments measured at net asset value(1) Fair Value Measured at Net Asset Value Per Share [Member] Comprehensive (loss) income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Interest rate Financing Receivable, Weighted-Average Interest Rate Financing Receivable, Weighted-Average Interest Rate New Accounting Pronouncements or Change in Accounting Principle [Table] Accounting Standards Update and Change in Accounting Principle [Table] Noncontrolling Interests Noncontrolling Interest [Member] Investments in and Advances to Non-Consolidated Affiliates Equity Method Investments [Policy Text Block] Loss Contingency Accrual [Abstract] Loss Contingency Accrual, Disclosures [Abstract] Ownership percentage Equity Method Investment, Ownership Percentage Revenue, Major Customer [Line Items] Concentration Risk [Line Items] Net deferred income tax (assets) liabilities Deferred Tax Assets, Net Property, plant and equipment, gross Property, Plant and Equipment, Gross, Excluding Construction In Progress Property, Plant and Equipment, Gross, Excluding Construction In Progress Large scale machinery Large scale machinery [Member] Large scale machinery [Member] PEO Actually Paid Compensation Amount PEO Actually Paid Compensation Amount Asset allocation Allocation in aggregate Defined Benefit Plan, Plan Assets, Actual Allocation, Percentage Percentage of foreign benefit obligation to total benefit obligation Percentage of Foreign Benefit Obligation to Total Benefit Obligation Percentage of Foreign Benefit Obligation to Total Benefit Obligation Hedging Designation [Axis] Hedging Designation [Axis] Debt Instrument, Fair Value Disclosure Debt Instrument, Fair Value Disclosure Reconciliation of unrecognized tax benefits Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block] 18. OTHER (INCOME) EXPENSES, NET Other Nonoperating Income and Expense [Text Block] Modification amount Debt Instrument, Modification Amount Debt Instrument, Modification Amount Change in pension and other benefits, net of tax provision (benefit), included in other comprehensive (loss) income Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, after Tax Derivative Contract Type [Domain] Derivative Contract [Domain] Net investment hedges Net Investment Hedging [Member] Effect of currency exchange Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Effect of Currency Exchange Arising During Period, before Tax Accumulated Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Effect of Currency Exchange Arising During Period, before Tax Aggregate Intrinsic Value, Exercised Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Aggregate Intrinsic Value, Exercised Share-based Compensation Arrangement by Share-based Payment Award, Non-Option Equity Instruments, Aggregate Intrinsic Value, Exercised 2031 Defined Benefit Plan, Expected Future Benefit Payment, Year Five Requisite service period (years) Share-Based Compensation Arrangement by Share-Based Payment Award, Award Requisite Service Period All Individuals All Individuals [Member] Expected additional contribution to funded pension plan Additional Contributions To Funded Pension Plan Additional Contributions To Funded Pension Plan Additional contributions to funded pension plan. Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Fair Value Disclosures [Abstract] Fair Value Disclosures [Abstract] Name Forgone Recovery, Individual Name Award expiration period Share-Based Compensation Arrangement by Share-Based Payment Award, Expiration Period 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] Disposal Group Classification [Axis] Disposal Group Classification [Axis] Series 2025 B Bonds, due June 2032 Series 2025 B Bonds, due June 2032 [Member] Series 2025 B Bonds, due June 2032 Foreign currency translation adjustment Goodwill, Foreign Currency Translation, Gain (Loss) Other, net Other Nonoperating Income (Expense), Nonsegment Other Nonoperating Income (Expense), Nonsegment Common stock, shares authorized Common Stock, Shares Authorized, Unlimited [Fixed List] 3.375% Senior Notes, due April 2029 Senior Notes due April 2029 [Member] Senior Notes due April 2029 Property, plant and equipment, net excluding construction in progress Property Plant and Equipment, net excluding construction in progress Property Plant and Equipment, net excluding construction in progress Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Aggregate Intrinsic Value Share-Based Compensation Arrangement by Share-Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value [Abstract] Line of Credit Facility [Line Items] Line of Credit Facility [Line Items] Derivative, Average Fixed Interest Rate Derivative, Average Fixed Interest Rate Geographical [Axis] Geographical [Axis] Liabilities Derivative Liability [Abstract] Exercised Share-based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other than Options, Exercised, Aggregate Intrinsic Value Share-based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other than Options, Exercised, Aggregate Intrinsic Value Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Currency losses, net Gain (Loss), Foreign Currency Transaction, before Tax Erroneously Awarded Compensation Recovery Erroneously Awarded Compensation Recovery [Table] Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Sierre Loan, due October 2027 Sierre Loan, due October 2027 [Member] Sierre Loan, due October 2027 Aggregate Intrinsic Value, Exercisable Share-Based Compensation Arrangement by Share-Based Payment Award, Options, Vested and Expected to Vest, Exercisable, Aggregate Intrinsic Value Return of capital to our common shareholder Return of capital to our common shareholder Adjustments to Additional Paid in Capital, Dividends in Excess of Retained Earnings Maximum amortization period of unfunded actuarial liability Maximum Amortization Period of Unfunded Actuarial Liability Maximum Amortization Period of Unfunded Actuarial Liability Long-Lived Assets and Other Intangible Assets Impairment or Disposal of Long-Lived Assets, Including Intangible Assets, Policy [Policy Text Block] Outstanding, end of period Outstanding, beginning of period Share-based Compensation Arrangement By Share Based Payment Award, Equity Instruments Other than Options, Aggregate Intrinsic Value The intrinsic value of equity instruments other than stock options. Foreign tax credits Effective Income Tax Rate Reconciliation, Tax Credit, Foreign, Amount 2031 Lessee, Operating Lease, Liability, to be Paid, Year Five Restructuring Plan [Axis] Restructuring Plan [Axis] Metal price lag Impact Of Metal Price Lag Impact Of Metal Price Lag Fire Fire [Member] Tax credit carryforward Tax Credit Carryforward, Amount Short-term Debt, Type [Axis] Short-Term Debt, Type [Axis] Foreign Tax Income Tax Paid, Foreign, after Refund Received, Percent [Abstract] Income Tax Paid, Foreign, after Refund Received, Percent China Loan, due January 2029 China Loan, due January 2029 [Member] China Loan, due January 2029 Specialty Specialty And Other [Member] Specialty And Other [Member] Thereafter Finance Lease, Liability, to be Paid, after Year Five Exercised (Indian Rupees per share) Share-Based Compensation Arrangements by Share-Based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Period of indebtedness Debt Instrument, Period of Indebtedness Debt Instrument, Period of Indebtedness Award Timing Disclosures [Line Items] Schedule of Inventories Schedule of Inventory, Current [Table Text Block] Service cost Defined Benefit Plan, Service Cost Other comprehensive (loss) income before reclassifications Other Comprehensive Income (Loss), before Reclassifications, Net of Tax Exercised (shares) Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Exercised Interest rate at period end Debt Instrument, Interest Rate During Period Net income attributable to our common shareholder Net income attributable to our common shareholder Net income attributable to our common shareholder Net Income (Loss) Attributable to Parent Equity Method Investment, Nonconsolidated Investee [Domain] Equity Method Investment, Nonconsolidated Investee [Domain] Losses recognized on balance sheet remeasurement currency exchange contracts, net Unrealized Gains Losses On Balance Sheet Remeasurement Currency Exchange Contracts Net Unrealized gains (losses) on balance sheet remeasurement currency exchange contracts, net. 2. RESTRUCTURING AND IMPAIRMENT Restructuring, Impairment, and Other Activities Disclosure [Text Block] Reconciliation of Canadian statutory tax rates to effective tax rates Schedule of Effective Income Tax Rate Reconciliation [Table Text Block] Accounts payable Accounts Payable and Accrued Liabilities, Current [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period Share-Based Compensation Arrangement by Share-Based Payment Award, Award Vesting Period Allowance for Doubtful Accounts Receivable [Roll Forward] Accounts Receivable, Allowance for Credit Loss [Roll Forward] Other Adjustments Effective Income Tax Rate Reconciliation, Other Adjustments, Percent Segment Reporting Information [Line Items] Segment Reporting Information [Line Items] Taxes payable Taxes Payable Adoption Date Trading Arrangement Adoption Date North America Segment North America Segment [Member] North America Segment Major Customers [Axis] Customer [Axis] Selling, General and Administrative Expenses Selling, General and Administrative Expenses, Policy [Policy Text Block] Adjusted EBITDA Adjusted EBITDA Operating Income (Loss) Customer-related Intangible Assets Customer Relationships [Member] Line of Credit Line of Credit [Member] Number of Continents in which Entity Operates Number of Continents in which Entity Operates Number of Continents in which Entity Operates Retained earnings Retained Earnings (Accumulated Deficit) Leaseholds and Leasehold Improvements Leaseholds and Leasehold Improvements [Member] Schedule of net funded status Schedule of Net Funded Status [Table Text Block] Supplier Concentration Risk Supplier Concentration Risk [Member] Derivative, Remaining Maturity Derivative, Remaining Maturity 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] Cash Flow Hedge Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] Environmental Liabilities Environmental Costs, Policy [Policy Text Block] 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 liabilities Deferred Tax Liabilities, Other Retirement Plan Type [Axis] Retirement Plan Type [Axis] Statement [Table] Statement [Table] Other expenses (income), net Other expenses (income), net Other Nonoperating Income (Expense) Actual return on plan assets Defined Benefit Plan, Plan Assets, Increase (Decrease) for Actual Return (Loss) Deferred income taxes Total deferred Deferred Income Tax Expense (Benefit) Adjustments to determine net cash provided by operating activities: Adjustment to Reconcile Net Income to Cash Provided by (Used in) Operating Activity [Abstract] FINANCING ACTIVITIES Cash Provided by (Used in) Financing Activity, Including Discontinued Operation [Abstract] Net sales Revenue Benchmark [Member] Ulsan Aluminum, Ltd. Ulsan Aluminum, Ltd. [Member] Ulsan Aluminum, Ltd. [Member] Other Foreign Jurisdictions Foreign Tax Jurisdiction, Other [Member] Auditor Information [Abstract] Auditor Information [Abstract] Balance (in shares) Balance (in shares) Shares, Issued Variable Rate [Domain] Variable Rate [Domain] Finance Lease, Liability, Noncurrent Finance Lease, Liability, Noncurrent Automotive Automotive Products [Member] Automotive Products [Member] Other accounts receivable Other Receivables, Gross, Current All Adjustments to Compensation All Adjustments to Compensation [Member] Tax credit carryforward, valuation allowance Tax Credit Carryforward, Valuation Allowance Currency (gains) losses included in "Other (income) expense, net" Schedule Of Foreign Currency Gains Losses Included In Statement Of Financial Performance [Table Text Block] Schedule of foreign currency gains losses included in statement of financial performance. Amendment Flag Amendment Flag Sale of stock, price per share (in dollars per share) Sale of Stock, Price Per Share Other Benefits [Member] Other Postretirement Benefits Plan [Member] Target and actual allocation of plan assets Schedule of Allocation of Plan Assets [Table Text Block] Termination Date Trading Arrangement Termination Date Insider Trading Policies and Procedures Adopted Insider Trading Policies and Procedures Adopted [Flag] Domestic - Federal Tax Income Tax Paid, Federal, after Refund Received, Percent Income Tax Paid, Federal, after Refund Received, Percent Operating Lease, Weighted Average Discount Rate, Percent Operating Lease, Weighted Average Discount Rate, Percent Accrued income tax penalties and interest Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Inventory charges Inventory Write-down Pension plans with accumulated benefit obligations in excess of plan assets, projected benefit obligation Pension Plans with Projected Benefit Obligations Less than Plan Assets, Projected Benefit Obligation Pension Plans with Projected Benefit Obligations Less than Plan Assets, Projected Benefit Obligation Richmond and Fairmont Plants Richmond and Fairmont Plants [Member] Richmond and Fairmont Plants 2023 Term Loans 2023 Term Loans [Member] 2023 Term Loans Currency impact Supplier Finance Program, Obligation, Period Increase (Decrease) Segment Reporting [Abstract] Segment Reporting [Abstract] Cost of Revenue Cost of Revenue Name of Supplier [Domain] Supplier [Domain] Debt Disclosure [Abstract] Debt Disclosure [Abstract] Defined Benefit Plan, Asset Categories [Axis] Defined Benefit Plan, Plan Assets, Category [Axis] Accounts Recovered/(Written-Off) Accounts Receivable, Allowance for Credit Loss, Writeoff Debt discount Debt Instrument, Unamortized Discount Schedule of inventories Inventory, Net [Abstract] Realized losses (gains) on derivative instruments not included in Adjusted EBITDA Realized Gain (Loss) on Derivative Instruments, Not Included in Segment Income Realized Gain (Loss) on Derivative Instruments, Not Included in Segment Income Tax credits Income Tax Reconciliation, Canadian Statutory Income Tax Rate, Tax Credits and other allowances The sum of the differences between the effective income tax rate and Canadian statutory income tax rate that can be explained by all tax credits generated or utilized under enacted tax laws during the period and other allowances. Restructuring and Related Activities [Abstract] Restructuring and Related Activities [Abstract] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Depreciation and amortization Deferred Tax Assets, Property, Plant and Equipment and Intangibles Amount before allocation of valuation allowances of deferred tax asset attributable to deductible temporary differences from property, plant, and equipment and intangible assets. Share-based Compensation by Award [Line Items] Share-Based Compensation Arrangement by Share-Based Payment Award [Line Items] Consolidated Entities [Axis] Consolidated Entities [Axis] Senior Notes Due 2030 Senior Notes Due 2030 [Member] Senior Notes Due 2030 [Member] 2032 through 2036 Defined Benefit Plan, Expected Future Benefit Payment, after Year Five for Next Five Years Withholding tax expense Effective Income Tax Rate Reconciliation, Withholding Tax Expense, Percent Effective Income Tax Rate Reconciliation, Withholding Tax Expense, Percent Foreign exchange translation and remeasurement Effective Income Tax Rate Reconciliation, Cross-Border Tax Effect, Amount Range of Estimated Useful Lives Range of Estimated Useful Lives [Table Text Block] Range of Estimated Useful Lives [Table Text Block] Use of Estimates and Assumptions Use of Estimates, Policy [Policy Text Block] Accrued expenses and other current liabilities Liability, Defined Benefit Plan, Current Finance Lease, Interest Payment on Liability Finance Lease, Interest Payment on Liability Return of capital to our common shareholder Payments of Dividends Construction in progress Construction in Progress, Gross Assumptions used in estimating fair value of each SAR under LTIP Schedule of Share-Based Payment Award, Employee Stock Purchase Plan, Valuation Assumptions [Table Text Block] Income tax (benefit) provision related to items of other comprehensive income Other Comprehensive Income (Loss), Tax, Portion Attributable to Parent Proceeds from the sale of a business Proceeds from Sales of Business, Affiliate and Productive Assets Insider Trading Arrangements [Line Items] Postemployment benefits lability, current Postemployment Benefits Liability, Current Floating rate Term Loans, due March 2032 Floating rate Term Loans, due March 2032 [Member] Floating rate Term Loans, due March 2032 Undistributed earnings of foreign subsidiaries (outside Canada) Undistributed Earnings of Foreign Subsidiaries (Outside Canada) Undistributed Earnings of Foreign Subsidiaries (Outside Canada) Number of SARs Share-Based Compensation Arrangement by Share-Based Payment Award, Non-Option Equity Instruments, Outstanding [Roll Forward] Equity [Member] Equity Securities [Member] Prior year adjustments Effective Income Tax Rate Reconciliation, Prior Year Income Taxes, Percent Raw materials Inventory, Raw Materials, Gross Total liabilities Liabilities Liabilities Accounts receivable, net Accounts Receivable, after Allowance for Credit Loss, Current [Abstract] 2031 Finance Lease, Liability, to be Paid, Year Five Net sales – third party Sales Revenue, Third Party [Member] Sales Revenue, Third Party [Member] Pension Adjustments Prior Service Cost Pension Adjustments Prior Service Cost [Member] Additions based on tax positions related to the current period Unrecognized Tax Benefits, Increase Resulting from Current Period Tax Positions Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Unrealized losses (gains) on other derivative instruments, net Unrealized Gains Losses On Other Derivative Instruments Net Unrealized gains (losses) on other derivative instruments, net. Aggregate Intrinsic Value Aggregate Intrinsic Value [Abstract] Aggregate Intrinsic Value [Abstract] 3.250% Senior Notes, due November 2026 3.250% Senior Notes, due November 2026 [Member] 3.250% Senior Notes, due November 2026 Asia and Other Pacific Asia and Other Pacific [Member] Asia and Other Pacific [Member] Variable Rate [Axis] Variable Rate [Axis] Consolidation Items [Axis] Consolidation Items [Axis] Counterparty Name [Axis] Counterparty Name [Axis] Restructuring Charges, Statement of Income or Comprehensive Income [Extensible Enumeration] Restructuring Charges, Statement of Income or Comprehensive Income [Extensible Enumeration] Environmental Restoration Costs [Member] Environmental Restoration Costs [Member] South America South America Segment [Member] South America Segment Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Non-NEOs Non-NEOs [Member] Ball Ball [Member] Ball