Accounts Payable Current Accounts payable, trade Accounts Receivable Gross Accounts receivables Accounts Receivable Net Current Receivables from customers, less allowances of $44 in 2012 and $46 in 2011 (L) Accrual For Environmental Loss Contingencies Remediation reserve balance Accrual For Environmental Loss Contingencies Payments Payments related to remediation expenses applied against the reserve Accrual For Environmental Loss Contingencies Period Increase Decrease Remediation reserve increase Accrued Environmental Loss Contingencies Current Remediation reserve balance, classified as a current liability Accumulated Depreciation Depletion And Amortization Property Plant And Equipment Less: accumulated depreciation, depletion, and amortization Accumulated Other Comprehensive Income Loss Net Of Tax Accumulated other comprehensive loss Accumulated Other Comprehensive Income [Member] Accumulated other comprehensive loss [Member] Acres Of Land Acres Of Land Acres of land associated with divestitures Additional acquired shares Additional Acquired Shares Additional acquired share Additional Paid In Capital Additional capital Additional Paid In Capital [Member] Additional capital [Member] Adjustments To Additional Paid In Capital Sharebased Compensation Requisite Service Period Recognition Value Stock-based compensation Adjustments To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities [Abstract] Adjustments to reconcile net (loss) income to cash from operations: Alcoa Aluminio [Member] Alcoa Aluminio [Member] Alcoa Aluminio [Member] Alcoa Joint Venture [Member] Alcoa Joint Venture [Member] Alcoa Joint Venture [Member] Allowance For Doubtful Accounts Receivable Current Receivables from customers, allowance Alumina Limited [Member] Alumina Limited [Member] Alumina Limited [Member] Alumina [Member] Alumina [Member] Alumina [Member] Aluminio [Member] Aluminio [Member] Aluminio [Member] Aluminium Bahrain B.S.C. Vs. Alcoa Inc. [Member] Aluminium Bahrain B S C Vs Alcoa Inc [Member] Alba [Member] Aluminum Contracts [Member] Aluminum Contracts [Member] Aluminum Contracts [Member] Aluminum futures designated as fair value hedges in kilo metric ton. Aluminum Futures Designated As Fair Value Hedges In Kilo Metric Ton Amount of aluminum kmt designated as fair value hedges Amendment Flag Amendment Flag Amount Invested Under Project Financing Amount Invested Under Project Financing Amount invested by Alcoa and Aluminum Financing Limited Amount Of Sold Receivables Remain Uncollected Amount Of Sold Receivables Remain Uncollected Sold receivables that remain uncollected Antidilutive Securities Excluded From Computation Of Earnings Per Share Amount Number of anti-dilutive securities Antidilutive Securities Excluded From Computation Of Earnings Per Share By Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities Excluded From Computation Of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Name [Domain] Antidilutive Securities, Name [Domain] Applicable margin on London Inter Bank Offer Rate loans. Applicable Margin On London Interbank Offer Rate Loans Applicable Margin On LIBOR Assets Total assets Assets [Abstract] ASSETS Assets Current Total current assets Assets Current [Abstract] Current assets: Assured energy. Assured Energy Assured energy, megawatts Assured power from installed capacity. Assured Power From Installed Capacity Assured power from installed capacity Availableforsale Securities [Member] Available-for-sale securities [Member] Average percentage of credit spread. Average Percentage Of Credit Spread Percentage of credit spread Baie Comeau Quebec Canada [Member] Baie Comeau Quebec Canada [Member] Baie Comeau [Member] Balance Sheet Location [Axis] Balance Sheet Location [Axis] Balance Sheet Location [Domain] Balance Sheet Location [Domain] Barra Grande [Member] Barra Grande [Member] Barra Grande [Member] Base Year Consumer Price Index Base Year Consumer Price Index Consumer price index base Basis Of Presentation And Significant Accounting Policies [Text Block] Basis Of Presentation Bond Series Two Thousand Twelve [Member] Bond Series Two Thousand Twelve [Member] Bond Series 2012 [Member] Breaches Of Warranty [Member] Breaches Of Warranty [Member] Breaches Of Warranty [Member] Business Acquisition [Line Items] Business Acquisition [Line Items] Business Acquisition [Table] Business Acquisition [Table] Business Acquisition [Table] Canada And Norway [Member] Canada And Norway [Member] Canada And Norway [Member] Capital Contribution Capital Contribution Additional contributions Capital investment commitment paid in period. Capital Investment Commitment Paid In Period Capital investment commitment paid in period The amount of cash contributed by an entity through the most recent balance sheet date to a joint venture accounted for under the equity method related to asset construction costs. Capital Investment Commitment Paid To Date Capital investment commitment paid-to-date Capital Investment, Over Year Capital Investment Over Year Term of investment by Alcoa and Aluminum Financing Limited, years Cash And Cash Equivalents At Carrying Value CASH AND CASH EQUIVALENTS AT END OF PERIOD Cash and cash equivalents at beginning of year Cash and cash equivalents Cash And Cash Equivalents [Member] Cash and Cash Equivalents [Member] Cash And Cash Equivalents Period Increase Decrease Net change in cash and cash equivalents Cash Flow Hedge Gain Loss To Be Reclassified Within Twelve Months Amount of loss expected to be recognized into earnings over the next 12 months Cash Provided By Used In Operating Activities Discontinued Operations CASH USED FOR DISCONTINUED OPERATIONS Charge related to European commission announcement. Charge Related To European Commission Announcement Charge related to European commission announcement Collateral Already Posted Aggregate Fair Value Margin posted Commercial Paper Commercial paper Commercial Paper [Member] Commercial Paper [Member] Commitment Of Additional Funding For Development Of Reserves Commitment Of Additional Funding For Development Of Reserves Additional funding received Commitments And Contingencies CONTINGENCIES AND COMMITMENTS (G) Commitments And Contingencies Disclosure [Text Block] Contingencies And Commitments Common Stock Dividends Per Share Cash Paid Dividends paid per common share Common Stock Dividends Per Share Declared Common stock, dividends per share Common Stock [Member] Common stock [Member] Common Stock Value Common stock Provides a description and amount of each detailed component of other nonoperating income and expenses. The description provided for other nonoperating income may include: (a) dividends, (b) interest on securities, (c) profits on securities (net of losses), and (d) miscellaneous other income items. The description provided for other nonoperating expenses may include: (a) losses on securities (net of profits) and (b) miscellaneous income deductions. Component Of Other Income Expense Nonoperating Table [Text Block] Schedule Of Other Income, Net Component Of Other Income Nonoperating [Line Items] Component of Other Income, Nonoperating [Line Items] Component Of Other Income Nonoperating [Table] Component of Other Income, Nonoperating [Table] Comprehensive Income Net Of Tax Comprehensive (loss) income Consumer Price Index Base Year Consumer Price Index Base Year Consumer price index base year Contributed amount to project. Contributed Amount To Project Commitment expended on the project Contributions From Noncontrolling Interests Contributions Convertible Notes [Member] Convertible Notes [Member] Convertible notes [Member] Corporate [Member] Corporate [Member] Cost Of Goods Sold Cost of goods sold (exclusive of expenses below) Cost Of Goods Sold Depreciation Depletion And Amortization Provision for depreciation, depletion, and amortization Cost Of Sales [Member] Cost of Goods Sold [Member] Credit Spread Between Alcoa And Counterparty [Member] Credit Spread Between Alcoa And Counterparty [Member] Credit Spread Between Alcoa And Counterparty [Member] Current Asset [Member] Current Asset [Member] Current Asset [Member] Current Fiscal Year End Date Current Fiscal Year End Date Curtis vs Alcoa [Member] Curtis Vs Alcoa [Member] Curtis Vs Alcoa [Member] Damages awarded to plaintiff, pre-judgment interest. Damages Awarded To Plaintiff Pre Judgment Interest Damages awarded to plaintiff, pre-judgment interest Dampier Gas Pipeline [Member] Dampier Gas Pipeline [Member] Dampier Gas Pipeline [Member] Days Provided to Submit Observations And Comments. Days Provided To Submit Observations And Comments Days provided to submit observations and comments to the EC Debt Disclosure [Text Block] Debt Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument Convertible Interest Expense Add: interest expense related to convertible notes Debt Instrument Description Loan agreement to redeem the Bonds, descriptions Debt Instrument Face Amount Face amount of debt the hedges effectively convert from fixed to floating through 2018 Debt Instrument Interest Rate Stated Percentage Outstanding debt, interest rate Debt Instrument [Line Items] Debt Instrument [Line Items] Debt Instrument Name [Domain] Debt Instrument, Name [Domain] Debt Instrument Periodic Payment Interest Debt service requirements, interest maximum Debt Instrument Periodic Payment Principal Debt service requirements, principal Debt Instrument Redemption Price Percentage Of Principal Amount Debt Instrument Redemption Price Percentage Of Principal Amount Percentage of principal amount Debt instruments maturity date. Debt Instruments Maturity Date Debt instruments maturity date Debt Instrument [Table] Schedule of Long-term Debt Instruments [Table] Debt weighted average maturity days. Debt Weighted Average Maturity Days Weighted-average maturity days Deferred Income Tax Expense Benefit Deferred income taxes Deferred purchase price customer receivables Deferred Price Customer Receivables Deferred purchase price receivable Deferred Tax Assets Net Noncurrent Deferred income taxes Defined Benefit Pension Plan Liabilities Noncurrent Accrued pension benefits Defined Benefit Plan Amortization Of Gains Losses Recognized net actuarial loss Defined Benefit Plan Amortization Of Prior Service Cost Credit Amortization of prior service benefit Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Disclosure [Line Items] Defined Benefit Plan Expected Return On Plan Assets Expected return on plan assets Defined Benefit Plan Interest Cost Interest cost Defined Benefit Plan Net Periodic Benefit Cost Net periodic benefit cost Defined Benefit Plans Disclosures Defined Benefit Plans [Axis] Defined Benefit Plans and Other Postretirement Benefit Plans [Axis] Defined Benefit Plans [Domain] Defined Benefit Plans and Other Postretirement Benefit Plans [Domain] Defined Benefit Plan Service Cost Service cost Depreciation Depletion And Amortization Depreciation, depletion, and amortization Derivative Asset Fair Value Net Derivative Assets, Fair Value Derivative Assets Derivative asset amount Derivative By Nature [Axis] Derivative, by Nature [Axis] Derivative Contract Type [Domain] Derivative Contract Type [Domain] Derivative Fair Value Of Derivative Asset Fair value asset derivatives Derivative Fair Value Of Derivative Liability Fair value liability derivatives Derivative Financial Instruments Assets [Member] Assets Derivative Financial Instruments Liabilities [Member] Liabilities Derivative instrument, obligation under contracts expiration date. Derivative Instrument Obligation Under Contracts Expiration Date Contracts expiration date Derivative Instrument Risk [Axis] Derivative Instrument Risk [Axis] Derivative Instruments And Hedging Activities Disclosure [Text Block] Derivatives And Other Financial Instruments Derivative Instruments Gain Loss By Hedging Relationship [Axis] Hedging Relationship [Axis] Derivative Instruments Gain Loss By Hedging Relationship By Income Statement Location By Derivative Instrument Risk [Table] Derivative Instruments, Gain (Loss) by Hedging Relationship, by Income Statement Location, by Derivative Instrument Risk [Table] Derivative Instruments Gain Loss [Line Items] Derivative Instruments, Gain (Loss) [Line Items] Derivative Instruments Gain Loss Reclassified From Accumulated O C I Into Income Effective Portion Net Amount of Gain or (Loss) Reclassified from Accumulated OCI into Earnings (Effective Portion) Derivative Instruments Gain Loss Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Net Amount of Gain or (Loss) Recognized in Earnings on Derivatives (Ineffective Portion and Amount Excluded from Effectiveness Testing) Derivative Instruments Gain Loss Recognized In Income Net Amount of Gain or (Loss) Recognized in Earnings on Hedged Items Derivative Instruments Gain Loss Recognized In Income Related To Ineffective Portion Derivative Instruments Gain Loss Recognized In Income Related To Ineffective Portion Amount of gain or (loss) recognized in earnings related to ineffective portion of hedging relationships Derivative Instruments Gain Loss Recognized In Other Comprehensive Income Effective Portion Net Amount of Gain or (Loss) Recognized in OCI on Derivatives (Effective Portion) Derivative Instruments Gain Recognized In Income Ineffective Portion And Amount Excluded From Effectiveness Testing Earnings recognized in relation to amount excluded from the assessment of hedge effectiveness Derivative Liability Fair Value Net 1 Derivative Liabilities, Fair Value Derivative [Line Items] Derivative [Line Items] Derivative Maturity Dates Power contract maturity date Derivative Name [Domain] Derivative, Name [Domain] Derivative [Table] Derivative [Table] Designated As Hedging Instrument [Member] Derivatives Designated as Hedging Instruments [Member] Disclosure Acquisition And Divestitures Additional Information [Abstract] Disclosure Acquisition And Divestitures Additional Information [Abstract] Disclosure Acquisition And Divestitures Additional Information [Abstract] Disclosure Contingencies And Commitments Additional Information [Abstract] Disclosure Contingencies And Commitments Additional Information [Abstract] Disclosure Contingencies And Commitments Additional Information [Abstract] Disclosure Debt Additional Information [Abstract] Disclosure Debt Additional Information [Abstract] Disclosure Debt Additional Information [Abstract] Disclosure Derivatives And Other Financial Instruments Additional Information [Abstract] Disclosure Derivatives And Other Financial Instruments Additional Information [Abstract] Disclosure Derivatives And Other Financial Instruments Additional Information [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Carrying Values and Fair Values of Other Financial Instruments [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Carrying Values And Fair Values Of Other Financial Instruments [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Carrying Values and Fair Values of Other Financial Instruments [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Derivative Contract Assets and Liabilities that are Measured and Recognized at Fair Value on Recurring Basis [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Derivative Contract Assets And Liabilities That Are Measured And Recognized At Fair Value On Recurring Basis [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Derivative Contract Assets and Liabilities that are Measured and Recognized at Fair Value on Recurring Basis [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Fair Value Gains and Losses on Derivatives Contracts Recorded in Earnings [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Fair Value Gains And Losses On Derivatives Contracts Recorded In Earnings [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Fair Value Gains and Losses on Derivatives Contracts Recorded in Earnings [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Fair Values of Outstanding Derivative Contracts Recorded as Assets [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Fair Values Of Outstanding Derivative Contracts Recorded As Assets [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Fair Values of Outstanding Derivative Contracts Recorded as Assets [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Fair Values of Outstanding Derivative Contracts Recorded as Liabilities [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Fair Values Of Outstanding Derivative Contracts Recorded As Liabilities [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Fair Values of Outstanding Derivative Contracts Recorded as Liabilities [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Gain or Loss on Hedged Items and Derivative Contracts [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Gain Or Loss On Hedged Items And Derivative Contracts [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Gain or Loss on Hedged Items and Derivative Contracts [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Gains and Losses on Derivative Representing Either Hedge Ineffectiveness or Hedge Components Excluded from Assessment of Effectiveness are Recognized in Current Earnings [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Gains And Losses On Derivative Representing Either Hedge Ineffectiveness Or Hedge Components Excluded From Assessment [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Gains and Losses on Derivative Representing Either Hedge Ineffectiveness or Hedge Components Excluded from Assessment of Effectiveness are Recognized in Current Earnings [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Outstanding Forward Contracts that were Entered into Hedge Forecasted Transactions [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Outstanding Forward Contracts That Were Entered Into Hedge Forecasted Transactions [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Outstanding Forward Contracts that were Entered into Hedge Forecasted Transactions [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Quantitative Information for Level 3 Derivative Contracts [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Quantitative Information For Level 3 Derivative Contracts [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Quantitative Information for Level 3 Derivative Contracts [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Reconciliation of Activity for Derivative Contracts [Abstract] Disclosure Derivatives And Other Financial Instruments Schedule Of Reconciliation Of Activity For Derivative Contracts [Abstract] Disclosure - Derivatives and Other Financial Instruments - Schedule of Reconciliation of Activity for Derivative Contracts [Abstract] Disclosure Earning Per Share Additional Information [Abstract] Disclosure Earning Per Share Additional Information [Abstract] Disclosure Earning Per Share Additional Information [Abstract] Disclosure - Earnings Per Share - Reconciliation Of Information Used To Compute Basic And Diluted EPS [Abstract] Disclosure Earnings Per Share Reconciliation Of Information Used To Compute Basic And Diluted E P S [Abstract] Disclosure - Earnings Per Share - Reconciliation Of Information Used To Compute Basic And Diluted EPS [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Income Taxes Additional Information [Abstract] Disclosure Inventories Additional Information [Abstract] Disclosure Inventories Additional Information [Abstract] Disclosure Inventories Additional Information [Abstract] Disclosure - Inventories - Schedule of Inventory Components [Abstract] Disclosure Inventories Schedule Of Inventory Components [Abstract] Disclosure - Inventories - Schedule of Inventory Components [Abstract] Disclosure - Other (Income) Expenses, Net - Schedule of Other Income, Net [Abstract] Disclosure Other Income Expenses Net Schedule Of Other Income Net [Abstract] Disclosure - Other (Income) Expenses, Net - Schedule of Other Income, Net [Abstract] Disclosure - Pension and Other Postretirement Benefit - Schedule of Components of Net Periodic Benefit Cost [Abstract] Disclosure Pension And Other Postretirement Benefit Schedule Of Components Of Net Periodic Benefit Cost [Abstract] Disclosure - Pension and Other Postretirement Benefit - Schedule of Components of Net Periodic Benefit Cost [Abstract] Disclosure Receivables Additional Information [Abstract] Disclosure Receivables Additional Information [Abstract] Disclosure Receivables Additional Information [Abstract] Disclosure - Recently Adopted and Recently Issued Accounting - Additional Information [Abstract] Disclosure Recently Adopted And Recently Issued Accounting Additional Information [Abstract] Disclosure - Recently Adopted and Recently Issued Accounting - Additional Information [Abstract] Disclosure Restructuring And Other Charges Activity And Reserve Balances For Restructuring Charges [Abstract] Disclosure Restructuring And Other Charges Activity And Reserve Balances For Restructuring Charges [Abstract] Disclosure Restructuring And Other Charges Activity And Reserve Balances For Restructuring Charges [Abstract] Disclosure - Restructuring and Other Charges - Additional Information [Abstract] Disclosure Restructuring And Other Charges Additional Information [Abstract] Disclosure - Restructuring and Other Charges - Additional Information [Abstract] Disclosure Restructuring And Other Charges Schedule Of Restructuring And Other Charges By Reportable Segments Pretax [Abstract] Disclosure Restructuring And Other Charges Schedule Of Restructuring And Other Charges By Reportable Segments Pretax [Abstract] Disclosure Restructuring And Other Charges Schedule Of Restructuring And Other Charges By Reportable Segments Pretax [Abstract] Disclosure - Segment Information - Schedule of Operating Results and Assets of Alcoa's Reportable Segments [Abstract] Disclosure Segment Information Schedule Of Operating Results And Assets Of Alcoas Reportable Segments [Abstract] Disclosure - Segment Information - Schedule of Operating Results and Assets of Alcoa's Reportable Segments [Abstract] Disclosure - Segment Information - Schedule of Segment Reporting Information to Consolidated Net Income Attributable to Alcoa [Abstract] Disclosure Segment Information Schedule Of Segment Reporting Information To Consolidated Net Income Attributable To Alcoa [Abstract] Disclosure - Segment Information - Schedule of Segment Reporting Information to Consolidated Net Income Attributable to Alcoa [Abstract] Disclosure Subsequent Events Additional Information [Abstract] Disclosure Subsequent Events Additional Information [Abstract] Disclosure Subsequent Events Additional Information [Abstract] Discounted Cash Flow [Member] Discounted Cash Flow [Member] Discounted Cash Flow [Member] Disposal Groups Including Discontinued Operations Name [Domain] Disposal Groups, Including Discontinued Operations, Name [Domain] Amount of dividends paid to participating securities (unvested awards) on a basis equivalent to holders of an entity's common stock plus an allocation of the undistributed earnings of an entity to the participating securities on the same basis as the paid dividends. This deduction in the EPS reconciliation is only applicable in periods when an entity generates income as the holders of the participating securities do not share in the losses of an entity unlike a common shareholder. Dividends And Allocation Of Undistributed Earnings To Participating Securities Less: dividends and undistributed earnings allocated to participating securities Dividends Cash [Abstract] Cash dividends declared: Dividends Common Stock Cash Common @ $0.06 per share Dividends Preferred Stock Less: preferred stock dividends declared Dividends Preferred Stock Cash Preferred @ $1.875 per share Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Documentand Entity Information [Abstract] Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus Document Information [Table] Document Information [Table] Document Period End Date Document Period End Date Document Type Document Type Due From Third Parties Due From Third Parties Reduction in recovery amount Earnings Per Share [Abstract] EARNINGS PER SHARE ATTRIBUTABLE TO ALCOA COMMON SHAREHOLDERS (J): Earnings Per Share Basic Net (loss) income Earnings Per Share Basic [Abstract] Basic: Earnings Per Share Basic And Diluted By Common Class [Line Items] Earnings Per Share Basic And Diluted By Common Class [Line Items] Earnings Per Share Basic And Diluted By Common Class [Line Items] Earnings Per Share Diluted Net (loss) income Earnings Per Share Diluted [Abstract] Diluted: Earnings Per Share [Text Block] Earnings Per Share East St. Louis Site [Member] East St Louis Site [Member] East St Louis Site [Member] Effective Income Tax Rate Continuing Operations The effective tax rate Effective Income Tax Rate Reconciliation At Federal Statutory Income Tax Rate U.S. federal statutory rate