XML 74 R34.htm IDEA: XBRL DOCUMENT
v2.3.0.15

Recently Adopted And Recently Issued Accounting Guidance (Details) | 9 Months Ended
--- | ---
Sep. 30, 2011
Recently Adopted And Recently Issued Accounting Guidance |
Percentage of goodwill impairment that exists based on qualitative factors minimum | 50.00%

X
- Definition Percentage of Goodwill Impairment Exists Based On Qualitative Factors Minimum. + Details
Name: | aa_PercentageOfGoodwillImpairmentExistsBasedOnQualitativeFactorsMinimum
Namespace Prefix: | aa
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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