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Recently Adopted and Recently Issued Accounting Guidance - Additional Information (Detail) | Jun. 30, 2013
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Accounting Policies [Abstract] |
Fair value of an indefinite-lived intangible asset | 50.00%

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- Definition Percentage of assets fair value disclosure. + References No definition available. + Details
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Namespace Prefix: | aa_
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Balance Type: | na
Period Type: | instant

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- Details
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Namespace Prefix: | us-gaap_
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