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Summary Of Significant Accounting Policies (Weighted-Average Useful Lives Of Structures And Machinery And Equipment) (Details) | 12 Months Ended
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Dec. 31, 2011
Structures [Member] | Alumina [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 29
Structures [Member] | Primary Metals [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 34
Structures [Member] | Flat-Rolled Products [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 31
Structures [Member] | Engineered Products And Solutions [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 27
Machinery And Equipment [Member] | Alumina [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 25
Machinery And Equipment [Member] | Primary Metals [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 21
Machinery And Equipment [Member] | Flat-Rolled Products [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 21
Machinery And Equipment [Member] | Engineered Products And Solutions [Member] |
Property, Plant and Equipment [Line Items] |
Weighted-average useful lives of assets, years | 18

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- Details
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- Definition The average useful life of long-lived, physical assets used in the normal conduct of business and not intended for resale. Examples include land, buildings, machinery and equipment, and other types of furniture and equipment including, but not limited to, office equipment, furniture and fixtures, and computer equipment and software. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
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Period Type: | duration