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Earnings Per Share - Reconciliation of Information Used to Compute Basic and Diluted EPS (Detail) (USD $) In Millions, unless otherwise specified | 3 Months Ended | 12 Months Ended
--- | --- | ---
Dec. 31, 2012 | Sep. 30, 2012 | Jun. 30, 2012 | Mar. 31, 2012 | Dec. 31, 2011 | Sep. 30, 2011 | Jun. 30, 2011 | Mar. 31, 2011 | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2010
Earnings Per Share Basic And Diluted By Common Class [Line Items] |  |  |  |  |  |  |  |  |  |  |
Income from continuing operations attributable to Alcoa common shareholders | $ 242 | $ (143) | $ (2) | $ 94 | $ (193) | $ 172 | $ 326 | $ 309 | $ 191 | $ 614 | $ 262
Less: preferred stock dividends declared |  |  |  |  |  |  |  |  | 2 | 2 | 2
Income from continuing operations available to common equity |  |  |  |  |  |  |  |  | 189 | 612 | 260
Less: dividends and undistributed earnings allocated to participating securities |  |  |  |  |  |  |  |  |  | 1 | 1
Income from continuing operations available to Alcoa common shareholders-basic |  |  |  |  |  |  |  |  | 189 | 611 | 259
Add: interest expense related to convertible notes |  |  |  |  |  |  |  |  |  | 30 |
Income from continuing operations available to Alcoa common shareholders-diluted |  |  |  |  |  |  |  |  | $ 189 | $ 641 | $ 259
Average shares outstanding-basic |  |  |  |  |  |  |  |  | 1,067 | 1,061 | 1,018
Stock options |  |  |  |  |  |  |  |  | 3 | 7 | 6
Stock and performance awards |  |  |  |  |  |  |  |  | 6 | 4 | 1
Convertible notes |  |  |  |  |  |  |  |  |  | 89 |
Average shares outstanding-diluted |  |  |  |  |  |  |  |  | 1,076 | 1,161 | 1,025

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- Definition 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. + References No definition available. + Details
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- Definition Income or loss from continuing operations after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period). + References No definition available. + Details
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- Definition Income or loss from continuing operations after adjustments for dividends on preferred stock (declared in the period) and/or cumulative preferred stock (accumulated for the period) and dividends and undistributed earnings allocated to participating securities. + References No definition available. + Details
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- Definition Interest expense related to convertible debt instruments which has been recognized for the period, including the contractual interest coupon and amortization of the debt discount, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=6928298&loc=SL6036836-161870 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name FASB Staff Position (FSP) -Number APB14-1 -Paragraph 33 -Subparagraph b -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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- Definition Equity impact of aggregate cash, stock, and paid-in-kind dividends declared for preferred shareholders during the period. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Statement of Position (SOP) -Number 01-6 -Paragraph 14 -Subparagraph l -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Article 3 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.3-04) -URI http://asc.fasb.org/extlink&oid=6959260&loc=d3e187085-122770 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 942 -SubTopic 405 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6957935&loc=d3e64057-112817 + Details
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- Definition Amount of income (loss) from continuing operations attributable to the parent. Also defined as revenue less expenses and taxes from ongoing operations before extraordinary items but after deduction of those portions of income or loss from continuing operations that are allocable to noncontrolling interests. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 810 -SubTopic 10 -Section 45 -Paragraph 18 -URI http://asc.fasb.org/extlink&oid=7656940&loc=SL4613673-111683 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 28 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 28 -URI http://asc.fasb.org/extlink&oid=6943989&loc=d3e3602-108585 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.13) -URI http://asc.fasb.org/extlink&oid=6880815&loc=d3e20235-122688 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 29 -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher AICPA -Name Accounting Research Bulletin (ARB) -Number 51 -Paragraph 38 -Subparagraph b(1) -LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy. + Details
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