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For classified balance sheets, these bonds are considered current assets because they are remarketed weekly and the bonds could be required to be repaid upon demand if there is a failed remarketing. 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less current portion Asset Retirement Obligations, Noncurrent Change in Accounting Principle, Type [Domain] Change in Accounting Principle, Type [Domain] Defined benefit plan liabilities AOCI Tax, Attributable to Parent Accumulated Other Comprehensive Loss ("AOCL") Comprehensive Income (Loss) Note [Text Block] Aluminum Aluminum [Member] Aluminum Equity Components [Axis] Equity Components [Axis] Accounts receivable Increase (Decrease) in Accounts Receivable Product and Service [Domain] Product and Service [Domain] Related Party Related Party [Member] Taxes, net of refunds Income Tax Paid, after Refund Received Disaggregation of Revenue [Table] Disaggregation of Revenue [Table] Entity Interactive Data Current Entity Interactive Data Current Long-Term Debt Long-Term Debt [Member] Non-trade payables Non-Trade Payable, Current Non-Trade Payable, Current Net loss attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest Variable Interest Entity [Line Items] Variable Interest Entity [Line Items] Deferred taxes Deferred Income Tax Liabilities, Net Compensation Actually Paid vs. Other Measure Compensation Actually Paid vs. Other Measure [Text Block] Conversion of preferred stock to common stock (in shares) Stock Issued During Period, Shares, Conversion of Units Entity Small Business Entity Small Business Comprehensive income (loss) attributable to Century stockholders Comprehensive Income (Loss), Net of Tax, Attributable to Parent Termination Date Trading Arrangement Termination Date Accounts payable, trade Increase (Decrease) in Accounts Payable, Trade Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value, Recurring and Nonrecurring [Table] Sale of Hawesville Disposal Groups, Including Discontinued Operations, Disclosure [Text Block] Compensation Actually Paid vs. Total Shareholder Return Compensation Actually Paid vs. Total Shareholder Return [Text Block] MNPI Disclosure Timed for Compensation Value MNPI Disclosure Timed for Compensation Value [Flag] Due to affiliates Other Liabilities, Current Other assets Other Assets, Noncurrent Document Type Document Type 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] Derivative assets Derivative Asset, Current Accrued and other current liabilities Accrued Liabilities, Current Fair Value as of Grant Date Award Grant Date Fair Value Redemption price, percentage Debt Instrument, Redemption Price, Percentage Supply Commitment Arrangement [Domain] Supply Commitment Arrangement [Domain] Pay vs Performance Disclosure, Table Pay vs Performance [Table Text Block] Stock repurchase program, remaining authorized repurchase amount Share Repurchase Program, Remaining Authorized, Amount Arrangement Duration Trading Arrangement Duration Statement of Stockholders' Equity [Abstract] Statement of Stockholders' Equity [Abstract] Local Phone Number Local Phone Number Other Postretirement Benefits Other Postretirement Benefits Plan [Member] Entity Address, Postal Zip Code Entity Address, Postal Zip Code Entity Registrant Name Entity Registrant Name Debt covenant, restricted cash Disposal Group, Including Discontinued Operation, Debt Covenant, Restricted Cash Disposal Group, Including Discontinued Operation, Debt Covenant, Restricted Cash Insider Trading Policies and Procedures Not Adopted Insider Trading Policies and Procedures Not Adopted [Text Block] COMMITMENTS AND CONTINGENCIES (NOTE 13) Commitments and Contingencies Supply Commitment Supply Commitment [Member] Debt Instrument, Redemption, Period [Domain] Debt Instrument, Redemption, Period [Domain] Carbon credit repurchase liability Carbon Credit Repurchase Liability, Current Carbon Credit Repurchase Liability, Current Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Changed Peer Group, Footnote Changed Peer Group, Footnote [Text Block] Reclassification out of Accumulated Other Comprehensive Income [Axis] Reclassification out of Accumulated Other Comprehensive Income [Axis] Equity in losses of unconsolidated subsidiaries Equity in losses of unconsolidated subsidiaries Income (Loss) from Equity Method Investments Accounting Standards Update and Change in Accounting Principle [Table] Accounting Standards Update and Change in Accounting Principle [Table] Forgone Recovery due to Expense of Enforcement, Amount Forgone Recovery due to Expense of Enforcement, Amount Executive Category: Executive Category [Axis] Percentage of Grundartangi work force represented by the labor unions Percentage Of Foreign Work Force Covered Under New Labor Agreement The percentage of a Company's Icelandic work force that are subject to collective bargaining agreements. Income tax effect Other Comprehensive Income (Loss), Tax Operating and other supplies Inventory, Supplies, Net of Reserves Measurement input Equity Method Investments, Measurement Input Equity Method Investments, Measurement Input Counterparty Name [Axis] Counterparty Name [Axis] LIABILITIES AND SHAREHOLDERS’ EQUITY LIABILITIES AND SHAREHOLDERS’ EQUITY Liabilities and Equity [Abstract] Schedule of Financial Assets and Liabilities at Fair Value on a Recurring Basis Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Inventories Total inventories Inventory, Net All Award Types Award Type [Domain] Non-PEO NEO Average Compensation Actually Paid Amount Non-PEO NEO Average Compensation Actually Paid Amount Final Quarter Multiemployer Plan Tranche Two [Member] Multiemployer Plan Tranche Two Fair Value Measurements Fair Value Disclosures [Text Block] Variable Interest Entity [Table] Variable Interest Entity [Table] Level 3 Fair Value, Inputs, Level 3 [Member] Supplemental Cash Flow Information: Supplemental Cash Flow Information [Abstract] Treasury stock, shares, acquired (in shares) Treasury Stock, Shares, Acquired Percentage of principal amount redeemed Debt Instrument, Redemption Price, Percentage of Principal Amount Redeemed Glencore beneficial ownership Subsidiary, Ownership Percentage, Noncontrolling Owner PEO Name PEO Name Debt instrument, convertible, threshold percentage of stock price trigger Debt Instrument, Convertible, Threshold Percentage of Stock Price Trigger Geographical [Axis] Geographical [Axis] Accrued and other current liabilities Increase (Decrease) in Accrued Liabilities Restricted cash Restricted Cash Contract liabilities Contract with Customer, Liability Unrealized gain on financial instruments Unrealized gain on financial instruments Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] LIABILITIES: Financial Instruments, Financial Liabilities, Balance Sheet Groupings [Abstract] Grundartangi - HS, Landsvirkjun and OR Grundartangi - HS, Landsvirkjun and OR [Member] Grundartangi - HS, Landsvirkjun and OR [Member] Kenergy Kenergy [Member] Kenergy Repayments under Grundartangi casthouse debt facility Repayments of Secured Debt Stock Price or TSR Estimation Method Stock Price or TSR Estimation Method [Text Block] Entity Tax Identification Number Entity Tax Identification Number Legal Entity [Axis] Legal Entity [Axis] 2.75% convertible senior notes due May 1, 2028, net of financing fees of $0.6 million at June 30, 2026, interest payable semiannually Convertible Notes Payable, Noncurrent Labor Commitments [Abstract] Labor Commitments [Abstract] Cash, cash equivalents and restricted cash, beginning of period Cash, cash equivalents and restricted cash, end of period Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Continuing Operation Entity Incorporation, State or Country Code Entity Incorporation, State or Country Code Aggregate Erroneous Compensation Not Yet Determined Aggregate Erroneous Compensation Not Yet Determined [Text Block] Schedule of Reclassification Out of AOCI Reclassification out of Accumulated Other Comprehensive Income [Table Text Block] Material Terms of Trading Arrangement Material Terms of Trading Arrangement [Text Block] Non-NEOs Non-NEOs [Member] 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] Industrial revenue bonds Industrial Revenue Bonds [Member] A borrowing supported by a written promise to pay an obligation. Iceland ICELAND General Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Comprehensive income (loss) Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Debt Instrument [Axis] Debt Instrument [Axis] Share-based compensation Share-Based Payment Arrangement, Noncash Expense Asset retirement obligations Disposal Group, Including Discontinued Operation, Asset Retirement Obligations Disposal Group, Including Discontinued Operation, Asset Retirement Obligations Litigation settlement, annual installment Litigation Settlement, Annual Installment Litigation Settlement, Annual Installment Disposal Group Name [Axis] Disposal Group Name [Axis] Schedule of Debt Schedule of Debt [Table Text Block] Quarterly cost Multiemployer Plan, Employer Contribution, Quarterly Cost Multiemployer Plan, Employer Contribution, Quarterly Cost Variable interest rate Debt Instrument, Variable Interest Rate Debt Instrument, Variable Interest Rate Schedule of Inventories Schedule of Inventory, Current [Table Text Block] Long-term Debt, Type [Domain] Long-Term Debt, Type [Domain] Basic (in dollars per share) Net income (loss) allocated to common stockholders (in dollars per share) Earnings Per Share, Basic Measurement Input Type [Axis] Measurement Input Type [Axis] Multiemployer Plan Tranche [Axis] Multiemployer Plan Tranche [Axis] Multiemployer Plan Tranche Adjusted price per megawatt Measurement Input, Adjusted Price Per Megawatt [Member] Measurement Input, Adjusted Price Per Megawatt Total current assets Total current assets Assets, Current Statistical Measurement [Axis] Statistical Measurement [Axis] Insider Trading Arrangements [Line Items] Long-term debt Long-Term Debt, Excluding Current Maturities Purchases from Glencore Cost of Revenue Award Type Award Type [Axis] Named Executive Officers, Footnote Named Executive Officers, Footnote [Text Block] Accounts receivable - net Accounts Receivable, after Allowance for Credit Loss, Current Accumulated deficit Retained Earnings (Accumulated Deficit) Defined benefit plans and other postretirement benefits: Other Comprehensive (Income) Loss, Defined Benefit Plan, after Reclassification Adjustment, before Tax [Abstract] Commodity contracts Commodity Contract [Member] Product and Service [Axis] Product and Service [Axis] Glencore Glencore [Member] Major customer whose sales revenue exceeded ten percentage of net sales. 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] Awards Close in Time to MNPI Disclosures Awards Close in Time to MNPI Disclosures [Table] Pension Benefits Pension Plan [Member] Common stock Common Stock [Member] Reclassification out of Accumulated Other Comprehensive Income [Table] Reclassification out of Accumulated Other Comprehensive Income [Table] Jamalco Jamalco [Member] Jamalco Compensation Actually Paid vs. Company Selected Measure Compensation Actually Paid vs. Company Selected Measure [Text Block] Cover [Abstract] Cover [Abstract] Fair Value Measurement Inputs and Valuation Techniques [Table] Fair Value Measurement Inputs and Valuation Techniques [Table] Derivative Contract [Domain] Derivative Contract [Domain] Major customer, percentage of revenue, net (percent) Concentration Risk, Percentage Concentration Risk Benchmark [Axis] Concentration Risk Benchmark [Axis] Foreign line of credit Foreign Line of Credit [Member] Equity Awards Adjustments Equity Awards Adjustments [Member] Total liabilities and equity TOTAL Liabilities and Equity Interest income Interest Income, Other Employee Stock Option Share-Based Payment Arrangement, Option [Member] Noncontrolling interests Equity, Attributable to Noncontrolling Interest Segments [Axis] Segments [Axis] Additional 402(v) Disclosure Additional 402(v) Disclosure [Text Block] Proceeds from issuance of Senior Notes due 2032 Proceeds from Issuance of Senior Long-Term Debt Related Party [Domain] Related and Nonrelated Parties [Domain] Tabular List, Table Tabular List [Table Text Block] Additional paid-in capital Additional Paid in Capital Required termination period Power Supply Agreement, Required Termination Period Power Supply Agreement, Required Termination Period Other income (loss) - net Other Nonoperating Income (Expense) Total Century equity Parent [Member] Convertible senior notes (in shares) Incremental Common Shares Attributable to Dilutive Effect of Conversion of Debt Securities Other operating expenses - net Other operating expense - net Other Operating Income (Expense), Net Name Awards Close in Time to MNPI Disclosures, Individual Name 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] Stock repurchase program, authorized, increase amount Stock Repurchase Program, Additional Authorized Amount Amount of additional stock repurchase plan authorization. Non-trade receivables Increase (Decrease) In Nontrade Payables Increase (Decrease) In Nontrade Payables Percentage of output retained, utilized, or sold by the company Subsidiary, Percentage Of Output Retained, Utilized, Or Sold By The Company Subsidiary, Percentage Of Output Retained, Utilized, Or Sold By The Company Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Reduction in production percentage Temporary Reduction In Production, Percentage Temporary Reduction In Production, Percentage Ravenswood Retiree Medical Benefits Changes Ravenswood Retiree Medical Benefits Changes [Member] Ravenswood Retiree Medical Benefits Changes [Member] Preferred stock (Note 14) Preferred Stock, Value, Issued Adjustment to Compensation: Adjustment to Compensation [Axis] U.S. revolving credit facility Domestic Line of Credit [Member] Net amount reclassified to net income (loss) Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax Hedging Designation [Domain] Hedging Designation [Domain] Inflation Reduction Act Inflation Reduction Act [Member] Inflation Reduction Act Directly related expense recovery recognized in Cost of goods sold Insurance Recovery Expense Insurance Recovery Expense Rule 10b5-1 Arrangement Terminated Rule 10b5-1 Arrangement Terminated [Flag] Aggregate Erroneous Compensation Amount Aggregate Erroneous Compensation Amount Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Interest Interest Paid, Excluding Capitalized Interest, Operating Activity Statement of Cash Flows [Abstract] Statement of Cash Flows [Abstract] Hedging Designation [Axis] Hedging Designation [Axis] Less: net income allocated to participating securities Undistributed Earnings (Loss) Allocated to Participating Securities, Basic Credit Facility [Axis] Credit Facility [Axis] Aggregate Available Trading Arrangement, Securities Aggregate Available Amount TOTAL Asset group fair value Assets, Fair Value Disclosure Discontinued Operations and Disposal Groups [Abstract] Name Measure Name Income Taxes Income Tax Disclosure [Text Block] Net gain on foreign currency cash flow hedges reclassified as income Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Pay vs Performance Disclosure [Line Items] Fair Value Hierarchy and NAV [Domain] Fair Value Hierarchy and NAV [Domain] Other non-cash items - net Other Noncash Income (Expense) Percentage of outstanding amount, offer to purchase Debt Offer To Purchase Percentage Of Outstanding Amount Debt Offer To Purchase Percentage Of Outstanding Amount Debt Instrument [Line Items] Debt Instrument [Line Items] HFO Price Swaps HFO Price Swaps [Member] HFO Price Swaps Pay vs Performance Disclosure Pay vs Performance Disclosure [Table] Retirement Plan Type [Domain] Retirement Plan Type [Domain] Additional paid-in capital Additional Paid-in Capital [Member] Entity Filer Category Entity Filer Category Revision of Prior Period [Axis] Revision of Prior Period [Axis] Name Trading Arrangement, Individual Name Cash and cash equivalents Cash and cash equivalents Cash and Cash Equivalent Expected term (years) Measurement Input, Expected Term [Member] Sebree Sebree [Member] Sebree Raw materials Inventory, Raw Materials, Net of Reserves Net gain (loss) on forward and derivative contracts - nonaffiliates Net loss on forward and derivative contracts Gain (Loss) on Derivative Instruments, Net, Pretax Concentration Risk Benchmark [Domain] Concentration Risk Benchmark [Domain] Company Selected Measure Amount Company Selected Measure Amount Schedule of Segment Information Segment Reporting, Reconciliation of Profit (Loss) by Segment to Consolidated [Table Text Block] Not designated as hedging instrument Not Designated as Hedging Instrument [Member] Depreciation, depletion and amortization Depreciation, Depletion and Amortization Litigation settlement installment period Litigation Settlement Installment Period Litigation Settlement Installment Period Entity Address, Address Line Two Entity Address, Address Line Two Share-based compensation (in shares) Shares Issued, Shares, Share-Based Payment Arrangement, after Forfeiture Net income (loss) Net income (loss) Net income Net income (loss) Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Gain on insurance proceeds - net Gain on insurance proceeds Gain on insurance proceeds - net Insurance Recoveries Derivative instruments Derivative Liability Century Aluminum Century Aluminum [Member] Century Aluminum Non-PEO NEO Non-PEO NEO [Member] Senior notes Senior Notes [Member] Amortization of net (gain) loss during the period Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss), Reclassification Adjustment from AOCI, before Tax Entity Address, Address Line One Entity Address, Address Line One Income tax (expense) benefit Income tax expense (benefit) Income tax effect Income tax (expense) benefit Income Tax Expense (Benefit) Effect of Dilutive Securities Dilutive Securities, Effect on Basic Earnings Per Share [Abstract] Customer concentration risk Customer Concentration Risk [Member] Cost of goods sold Cost of Goods Sold Reduction in cost of goods sold Cost of goods sold Cost of Product and Service Sold Award Timing Method Award Timing Method [Text Block] E ON Contingent Obligation E ON Contingent Obligation [Member] Obligation that is dependent on occurence of future events. CHANGE IN CASH, CASH EQUIVALENTS AND RESTRICTED CASH Cash, Cash Equivalent, Restricted Cash, and Restricted Cash Equivalent, Period Increase (Decrease), Including Exchange Rate Effect and Discontinued Operation Forgone Recovery, Explanation of Impracticability Forgone Recovery, Explanation of Impracticability [Text Block] Variable Interest Entity, Primary Beneficiary Variable Interest Entity, Primary Beneficiary [Member] Other current liabilities Loss Contingency, Accrual, Current Net gain arising during the period Other Comprehensive Income (Loss), Defined Benefit Plan, Gain (Loss) Arising During Period, before Tax Amortization of net (gain) loss Defined Benefit Plan, Amortization of Gain (Loss) AOCI Attributable to Parent, Net of Tax [Roll Forward] AOCI Attributable to Parent, Net of Tax [Roll Forward] Net income (loss) attributable to Century stockholders Net income (loss) attributable to Century stockholders Net of tax Net Income (Loss) Attributable to Parent Long-term Debt, Type [Axis] Long-Term Debt, Type [Axis] Erroneous Compensation Analysis Erroneous Compensation Analysis [Text Block] Location, Statement of Financial Position, Balance [Axis] Location, Statement of Financial Position, Balance [Axis] Proceeds from the sale of Hawesville Proceeds from Sale of Property, Plant, and Equipment Statement [Table] Statement [Table] Restatement Determination Date: Restatement Determination Date [Axis] Schedule of Accumulated Balances for Each Component of AOCI Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Litigation settlement amount Litigation Settlement, Amount Awarded to Other Party Contributions from joint venture partner Contributions From Joint Venture Partner Contributions From Joint Venture Partner Derivative asset Derivative Asset, Subject to Master Netting Arrangement, before Offset Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Defined Benefit Plans and Other Postretirement Benefit Plans Disclosures [Table] Reportable Segment Reportable Segment [Member] Reportable Segment Share-based compensation Share-Based Payment Arrangement [Member] U.S. and Iceland Revolving Credit Facilities U.S. and Iceland Revolving Credit Facilities [Member] U.S. and Iceland Revolving Credit Facilities Pension Benefits Adjustments, Footnote Pension Benefits Adjustments, Footnote [Text Block] Convertible senior notes Dilutive Securities, Effect on Basic Earnings Per Share, Dilutive Convertible Securities Derivative Instruments and Hedging Activities Disclosure [Abstract] Derivative Instruments and Hedging Activities Disclosure [Abstract]