XML 1085 R30.htm IDEA: XBRL DOCUMENT
v2.4.0.6

Interest Cost Components | 12 Months Ended
--- | ---
Dec. 31, 2012
Interest Cost Components | V. Interest Cost Components
|  | 2012 |  |  | 2011 |  |  | 2010 |
Amount charged to expense |  | $ | 490 |  |  | $ | 524 |  |  | $ | 494 |
Amount capitalized |  |  | 93 |  |  |  | 101 |  |  |  | 96 |
|  | $ | 583 |  |  | $ | 625 |  |  | $ | 590 |

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- Definition Interest Cost Components Disclosure [Text Block] + References No definition available. + Details
Name: | aa_InterestCostComponentsDisclosureTextBlock
Namespace Prefix: | aa_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration