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Inventories (Tables) | 9 Months Ended
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Sep. 30, 2012
Schedule of Inventory Components | E. Inventories
|  | September 30, 2012 |  |  | December 31, 2011 |
Finished goods |  | $ | 575 |  |  | $ | 537 |
Work-in-process |  |  | 933 |  |  |  | 911 |
Bauxite and alumina |  |  | 638 |  |  |  | 656 |
Purchased raw materials |  |  | 557 |  |  |  | 532 |
Operating supplies |  |  | 270 |  |  |  | 263 |
|  | $ | 2,973 |  |  | $ | 2,899 |

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- Definition 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. + References No definition available. + Details
Name: | aa_ScheduleOfInventoryComponentsDisclosuresTableTextBlock
Namespace Prefix: | aa_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration