Document and Entity Information [Abstract] Document And Entity Information [Abstract] Document and Entity Information Statement [Table] Statement [Line Items] Document Type Amendment Flag Document Period End Date Document Fiscal Year Focus Document Fiscal Period Focus Trading Symbol Entity Registrant Name Entity Central Index Key Current Fiscal Year End Date Entity Filer Category Entity Common Stock, Shares Outstanding Statement Of Consolidated Operations [Abstract] Sales (Q) Total sales Consolidated sales Sales (H) Cost of goods sold (exclusive of expenses below) Cost of Goods Sold, Total Cost of goods sold (exclusive of expenses below) Selling, general administrative, and other expenses Selling, General and Administrative Expense, Total Selling, general administrative, and other expenses Research and development expenses Research and Development Expense, Total Research and development expenses Provision for depreciation, depletion, and amortization Cost of Goods Sold, Depreciation, Depletion and Amortization, Total Provision for depreciation, depletion, and amortization Restructuring and other charges (C) Restructuring and other charges (C) Restructuring and other charges Restructuring and other charges Interest expense (V) Interest expense Amount charged to expense Interest Expense, Total Interest expense Other expenses, net (I) Other income, net (G) Other income, net Other expenses (income), net Other expenses (income), net Other expenses (income), net (O) The net total of all costs and expenses associated with normal operations and income and expenses associated with nonoperating activities, including interest and debt-related expenses. Total costs and expenses Total costs and expenses Total costs and expenses Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Cumulative Effects of Changes in Accounting Principles, Noncontrolling Interest Income (loss) from continuing operations before income taxes Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Cumulative Effects of Changes in Accounting Principles, Noncontrolling Interest, Total Income from continuing operations before income taxes (Benefit) provision for income taxes (N) Provision (benefit) for income taxes (M) (Benefit) provision for income taxes (T) Provision (benefit) for income taxes, Total Provision for income taxes Income (Loss) from Continuing Operations, Including Portion Attributable to Noncontrolling Interest (Loss) income from continuing operations Income from continuing operations Discontinued operations Loss from discontinued operations Loss from discontinued operations Discontinued operations Discontinued operations Loss from discontinued operations Loss from discontinued operations Discontinued operations Net (loss) income Net income Net income Less: Net income (loss) attributable to noncontrolling interests Less: Net income attributable to noncontrolling interests Less: Net income attributable to noncontrolling interests Net Income (Loss) Attributable to Noncontrolling Interest, Total Noncontrolling interests Net loss Consolidated net income (loss) attributable to Alcoa Consolidated net income (loss) attributable to Alcoa Net income NET INCOME ATTRIBUTABLE TO ALCOA Consolidated net income attributable to Alcoa AMOUNTS ATTRIBUTABLE TO ALCOA COMMON SHAREHOLDERS: Income (loss) from continuing operations Income (loss) from continuing operations Income from continuing operations attributable to Alcoa common shareholders (Loss) income from continuing operations Income (Loss) from Continuing Operations Attributable to Parent, Total Income from continuing operations Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent (Loss) income from discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Attributable to Parent, Total Loss from discontinued operations Earnings Per Share [Abstract] EARNINGS PER SHARE ATTRIBUTABLE TO ALCOA COMMON SHAREHOLDERS (I): Basic: Income (Loss) from Continuing Operations, Per Basic Share (Loss) income from continuing operations Income (Loss) from Continuing Operations, Per Outstanding Share, Total Income from continuing operations Income (Loss) from Discontinued Operations, Net of Tax, Per Basic Share (Loss) income from discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Per Outstanding Share, Total Loss from discontinued operations Earnings Per Share, Basic Net income Diluted: Income (Loss) from Continuing Operations, Per Diluted Share Income from continuing operations (Loss) income from continuing operations Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share (Loss) income from discontinued operations Income (Loss) from Discontinued Operations, Net of Tax, Per Diluted Share, Total Loss from discontinued operations Earnings Per Share, Diluted Net income Common Stock, Dividends, Per Share, Cash Paid Dividends paid per common share Statement Of Consolidated Comprehensive Income [Abstract] Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Noncontrolling Interest [Member] Non-Controlling Interests [Member] Other comprehensive (loss) income, net of tax: Other comprehensive income, net of tax: Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and postretirement benefit plans (W) Other Comprehensive Income, Defined Benefit Plans Adjustment, Net of Tax, Total Change in unrecognized net actuarial loss and prior service cost/benefit related to pension and other postretirement benefits Foreign currency translation adjustments (A) Other Comprehensive Income, Foreign Currency Transaction and Translation Adjustment, Net of Tax, Total Foreign currency translation adjustments Unrealized (losses) gains on available-for-sale securities: Unrealized gains on available-for-sale securities: Unrealized holding gains (losses) Unrealized gains (losses) on available-for-sale securities Unrealized holding gains Other Comprehensive Income Reclassification Adjustment For Sale Of Securities Included In Net Income Net Of Tax Net amount reclassified to earnings Net amount reclassified to earnings Net change in unrealized (losses) gains on available-for-sale securities Net change in unrealized gains on available-for-sale securities Unrecognized gains (losses) on derivatives (Q): Unrecognized losses on derivatives (L): Net change from periodic revaluations Net change from periodic revaluations Net amount reclassified to earnings Net amount reclassified to earnings Net unrecognized (losses) gains on derivatives Net change in unrecognized losses on derivatives Total Other comprehensive income (loss), net of tax Other comprehensive income (loss) Total Other comprehensive income, net of tax Other comprehensive income Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income Consolidated Balance Sheet [Abstract] ASSETS Cash and cash equivalents CASH AND CASH EQUIVALENTS AT END OF PERIOD Cash and cash equivalents at beginning of year Cash and cash equivalents (X) Cash and Cash Equivalents, at Carrying Value, Total Cash and cash equivalents Receivables from customers, less allowances of $46 in both 2011 and 2010 (U) Accounts Receivable, Net, Current, Total Receivables from customers, less allowances of $45 in 2012 and $46 in 2011 (J) Other receivables Other receivables (J) Inventories (G) Obsolete inventory charges Inventories, total Inventories (D) Prepaid expenses and other current assets Prepaid expenses and other current assets Total current assets Total current assets Properties, plants, and equipment Property, Plant and Equipment, Gross, Ending Balance Property, Plant and Equipment, Gross, Beginning Balance Properties, plants, and equipment, gross Properties, plants, and equipment Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less: accumulated depreciation, depletion, and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Ending Balance Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Beginning Balance Less: accumulated depreciation, depletion, and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment, Total Less: accumulated depreciation, depletion, and amortization Property Plant And Equipment Net Corporate fixed assets, net Property, Plant and Equipment, Net, Ending Balance Property, Plant and Equipment, Net, Beginning Balance Properties, plants, and equipment, net Properties, plants, and equipment, net Long-lived assets Goodwill Goodwill, net Goodwill, net Goodwill Goodwill, Net Corporate goodwill Long-term Investments Capital investment Long-term Investments, Total Investments Deferred Tax Assets, Net, Noncurrent Deferred Tax Assets, Net, Noncurrent, Total Deferred income taxes Other Assets Noncurrent Other noncurrent assets Other assets, noncurrent, total Other noncurrent assets Total assets Total assets, segment Total assets Total assets LIABILITIES Short Term Bank Loans And Notes Payable Short-term borrowings (K & X) Short-term borrowings (E) Commercial Paper Commercial paper Commercial paper (K & X) Accounts payable, trade Accounts Payable, Current, Total Accrued compensation and retirement costs Employee-related Liabilities, Current, Total Taxes, including income taxes Taxes Payable, Current, Total Other current liabilities Other Liabilities, Current, Total Long-term debt due within one year (K & X) Long-term Debt and Capital Lease Obligations, Current, Total Long-term debt due within one year (E) Total current liabilities Total current liabilities Long-term debt, less amount due within one year (K & X) Long-term Debt and Capital Lease Obligations, Total Long-term debt, less amount due within one year Accrued pension benefits (W) Accrued pension benefits Accrued other postretirement benefits (W) Accrued other postretirement benefits Other Liabilities Noncurrent Other noncurrent liabilities and deferred credits Other noncurrent liabilities and deferred credits, total Other Total liabilities Total liabilities Commitments and contingencies (N) CONTINGENCIES AND COMMITMENTS Contingencies and commitments (N) EQUITY Preferred Stock, Value, Issued Preferred Stock, Value, Issued, Ending Balance Preferred Stock, Value, Issued, Beginning Balance Preferred stock Preferred Stock, Value, Issued, Total Preferred stock (R) Common stock (R) Common Stock, Value, Issued, Ending Balance Common Stock, Value, Issued, Beginning Balance Common stock Common Stock, Value, Issued, Total Contribution to newly issued shares of its common stock Additional Paid In Capital Additional Paid in Capital, Ending Balance Additional Paid in Capital, Beginning Balance Additional capital Additional Paid in Capital, Total Additional capital Retained Earnings (Accumulated Deficit) Retained Earnings (Accumulated Deficit), Ending Balance Retained Earnings (Accumulated Deficit), Beginning Balance Retained Earnings (Accumulated Deficit), Total Retained earnings Treasury stock, at cost Treasury stock, at cost Treasury Stock, Value, Ending Balance Treasury Stock, Value, Beginning Balance Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated Other Comprehensive Income (Loss), Net of Tax, Ending Balance Accumulated Other Comprehensive Income (Loss), Net of Tax, Beginning Balance Accumulated Other Comprehensive Income (Loss), Net of Tax, Total Accumulated other comprehensive loss Total Alcoa shareholders' equity Stockholders' Equity Attributable to Parent, Ending Balance Stockholders' Equity Attributable to Parent, Beginning Balance Total Alcoa shareholders' equity Minority Interest Stockholders' Equity Attributable to Noncontrolling Interest, Ending Balance Stockholders' Equity Attributable to Noncontrolling Interest, Beginning Balance Noncontrolling interests Stockholders' Equity Attributable to Noncontrolling Interest, Total Noncontrolling shareholders' interests Total equity Balance Balance Total equity Total liabilities and equity Total liabilities and equity Receivables from customers, less allowances Balance at end of year Balance at beginning of year Receivables from customers, allowances Statement Of Consolidated Cash Flows [Abstract] CASH FROM OPERATIONS Adjustments to reconcile net income to cash from operations: Depreciation, depletion, and amortization Depreciation, Depletion and Amortization, Total Depreciation, depletion, and amortization Deferred Income Tax Expense (Benefit) Deferred total Deferred provision (benefit) for income taxes, total Deferred income taxes Equity (income) loss, net of dividends Equity income, net of dividends Income (Loss) from Equity Method Investments, Net of Dividends or Distributions, Total Net gain(loss) from investing activities - asset sales (I) Net loss from investing activities - asset sales (G) Net loss from investing activities - asset sales (I) Share-based Compensation Share-based Compensation, Total Stock-based compensation Excess tax benefits from stock-based compensationoperatingactivities Excess tax benefits from stock-based payment arrangements Excess tax benefits from stock-based payment arrangements Adjustments Noncash Items To Reconcile Net Income Loss To Cash Provided By Used In Operating Activities Other Other Other Noncash Income (Expense), Total Changes in assets and liabilities, excluding effects of acquisitions, divestitures, and foreign currency translation adjustments: (Increase) decrease in receivables (Increase) in receivables Increase (Decrease) in Receivables, Total (Increase) decrease in inventories (Increase) in inventories Increase (Decrease) in Inventories, Total Decrease in prepaid expenses and other current assets Decrease (increase) in prepaid expenses and other current assets Increase (Decrease) in Prepaid, Deferred Expense and Other Assets, Total Increase (decrease) in accounts payable, trade Increase in accounts payable, trade (Decrease) in accrued expenses Increase (Decrease) in Accrued Liabilities, Total Increase (Decrease) in Accrued Taxes Payable Increase (Decrease) in Accrued Taxes Payable, Total Increase in taxes, including income taxes Pension Contributions Pension contributions Cash contribution to pension plans (Increase) decrease in noncurrent assets (Increase) in noncurrent assets Increase (Decrease) in Other Operating Assets, Total Increase in noncurrent liabilities Increase (Decrease) in Other Operating Liabilities, Total Increase (Decrease) in Assets Held-for-sale (Increase) in net assets held for sale CASH PROVIDED FROM CONTINUING OPERATIONS CASH USED FOR CONTINUING OPERATIONS Cash (used for) provided from discontinued operations CASH USED FOR DISCONTINUED OPERATIONS CASH PROVIDED FROM (USED FOR) OPERATIONS CASH USED FOR OPERATIONS FINANCING ACTIVITIES Net change in short-term borrowings (K) Proceeds from (Repayments of) Short-term Debt, Total Net change in short-term borrowings (original maturities of three months or less) Proceeds from (Repayments of) Commercial Paper Net change in commercial paper Proceeds from (Repayments of) Commercial Paper, Total Net change in commercial paper (K) Additions to long-term debt (H) Additions to debt (original maturities greater than three months) (E) Proceeds from Issuance of Long-term Debt, Total Net proceeds received from public debt offering Debt issuance costs Debt issuance costs Payments on long-term debt Payments on debt (original maturities greater than three months) (E) Repayment of outstanding debt Repayments of Long-term Debt, Total Proceeds from exercise of employee stock options (R) Proceeds from exercise of employee stock options Excess tax benefits from stock-based payment arrangements Excess tax benefits from stock-based payment arrangements Dividends paid to shareholders Dividends paid to shareholders Payments of Distributions to Affiliates Distributions to noncontrolling interests Proceeds from Contributions from Affiliates Contributions from noncontrolling interests (I & M) Contributions from noncontrolling interests CASH (USED FOR) PROVIDED FROM FINANCING ACTIVITIES CASH PROVIDED FROM FINANCING ACTIVITIES INVESTING ACTIVITIES Capital expenditures Capital expenditures Payments to Acquire Property, Plant, and Equipment, Total Acquisitions, net of cash acquired Acquisitions, net of cash acquired Net cash (received) paid Net cash paid (received) Net cash paid (received) Proceeds from Sale of Productive Assets Proceeds from the sale of assets and businesses (F) Proceeds from Sale of Productive Assets, Total Proceeds from the sale of assets and businesses Additions to investments Additions to investments Payments to Acquire Investments, Total Sales of investments (I) Proceeds from Sale, Maturity and Collections of Investments, Total Sales of investments Payments for (Proceeds from) Other Investing Activities Other CASH (USED FOR) PROVIDED FROM INVESTING ACTIVITIES CASH USED FOR INVESTING ACTIVITIES Effect of exchange rate changes on cash and cash equivalents Effect of Exchange Rate on Cash and Cash Equivalents, Total EFFECT OF EXCHANGE RATE CHANGES ON CASH AND CASH EQUIVALENTS Net change in cash and cash equivalents Net change in cash and cash equivalents Statement Of Changes In Consolidated Equity [Abstract] Preferred Stock [Member] Preferred Stock [Member] Common Stock [Member] Common Stock [Member] Additional Paid In Capital [Member] Additional Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Treasury Stock [Member] Treasury Stock [Member] Accumulated Other Comprehensive Income [Member] Accumulated Other Comprehensive Loss [Member] Cash dividends declared: Preferred @ $0.9375 in 2010 and $1.875 in 2009 per share Preferred @ $0.9375 per share Common @ $0.03 per share Common @ $0.03 per share Common @ $0.26 for 2009, $0.12 for 2010, $0.12 for 2011 per share Common per share Common stock dividend per share Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Value Stock-based compensation Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition, Total Stock-based compensation Common stock issued: compensation plans Common stock issued: compensation plans Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures, Total Value of common stock shares newly issued Common stock issued to satisfy a portion of accrued pension benefits liability Common stock contributed to pension plans, aggregate price Issuance of common stock Common stock issued to satisfy a portion of accrued pension benefits liability Minority Interest Decrease From Distributions To Noncontrolling Interest Holders Noncontrolling interests Distributions Contributions From Noncontrolling Interests Contributions From Noncontrolling Interests Contributions Treasury stock, private placement Stockholders' Equity, Other Other Preferred Stock, Dividends Per Share, Declared Preferred stock, dividends per share Common stock, per share Common stock, dividends yield Common stock, dividends per share Basis Of Presentation [Abstract] Basis Of Presentation And Significant Accounting Policies TextBlock Basis Of Presentation Recently Adopted And Recently Issued Accounting Guidance [Abstract] New Accounting Pronouncements And Changes In Accounting Principles [Text Block] New Accounting Pronouncements And Changes In Accounting Principles [Text Block] Recently Adopted And Recently Issued Accounting Guidance Restructuring And Other Charges [Abstract] D. Restructuring and related activities disclosure textblock Restructuring And Other Charges Inventories [Abstract] Inventory Disclosure Text Block Inventories Debt [Abstract] Debt Disclosure [Text Block] Debt Contingencies And Commitments [Abstract] H. Commitments and Contingencies Contingencies And Commitments Other Income, Net [Abstract] Other (Income) Expenses, Net Other Income, Net Segment Information [Abstract] J. Segment Information Segment Information Segment And Geographic Area Information L. Earnings Per Share Earnings Per Share Receivables [Abstract] N. Accounts Receivable Securitizations Receivables Pension And Other Postretirement Benefits [Abstract] PensionAndOtherPostretirementBenefitsDisclosureTextBlock Pension And Other Postretirement Benefits Derivatives And Other Financial Instruments [Abstract] Derivative Instruments and Hedging Activities Disclosure [Text Block] Derivatives And Other Financial Instruments Subsequent Events [Abstract] ScheduleOfSubsequentEventsTextBlock Subsequent Events Subsequent Events An entity's restructuring charges before income tax by reportable segment had such charges been included in the entity's segment results. Schedule Of Pro Forma Restructuring Charges By Reportable Segment Before Income Tax Text Block Schedule Of Restructuring And Other Charges By Reportable Segments, Pretax Schedule of Restructuring Reserve by Type of Cost [Table Text Block] Activity And Reserve Balances For Restructuring Charges Disclosure of the carrying value of each significant component of inventory for an entity, who does not report such information on the face of their balance sheet. Schedule Of Inventory Components Disclosures Table [Text Block] Carrying Value Of Major Inventory Components Schedule Of Inventory Components