XML 22 R42.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Earnings Per Share (Narrative) (Details) (USD $) In Millions, except Per Share data, unless otherwise specified | 3 Months Ended
--- | ---
Mar. 31, 2012 | Mar. 31, 2011
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |
Participating securities outstanding, maximum | 1 | 2
Stock Options [Member] |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |
Weighted average exercise price of options | $ 15.47 | $ 32.27
Equity Unit Purchase Agreements [Member] |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |
Number of anti-dilutive securities | 28 | 15
Stock And Performance Awards [Member] |  |
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] |  |
Participating securities outstanding, nonforfeitable | 12 | 8

X
- Definition This element represents the number of outstanding nonvested stock awards that contain forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). + References No definition available. + Details
Name: | aa_NonvestedSharesWithForfeitableDividends
Namespace Prefix: | aa_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition This element represents the number of outstanding nonvested stock awards that contain non-forfeitable rights to dividends or dividend equivalents (whether paid or unpaid). + References No definition available. + Details
Name: | aa_ParticipatingNonvestedSharesWithNonForfeitableDividendRights
Namespace Prefix: | aa_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | instant

X
- Definition The weighted average exercise price of stock options whose individual exercise prices were greater than the average market price of an entity's common stock during the period. + References No definition available. + Details
Name: | aa_WeightedAverageExercisePriceOfUnderwaterOptions
Namespace Prefix: | aa_
Data Type: | num:perShareItemType
Balance Type: | na
Period Type: | duration

X
- Definition Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Antidilution -URI http://asc.fasb.org/extlink&oid=6505113 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 171 -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 Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 40 -Subparagraph c -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 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Statement of Financial Accounting Standard (FAS) -Number 128 -Paragraph 13, 14 -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 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Emerging Issues Task Force (EITF) -Number 07-4 -Paragraph 4 -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 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Diluted Earnings Per Share -URI http://asc.fasb.org/extlink&oid=6510752 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 260 -SubTopic 10 -Section 50 -Paragraph 1 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=6371337&loc=d3e3550-109257 Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Glossary Contingent Stock Agreement -URI http://asc.fasb.org/extlink&oid=6508534 + Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:sharesItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_AntidilutiveSecuritiesExcludedFromComputationOfEarningsPerShareLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration