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Summary of Significant Accounting Policies - Additional Information (Detail) (USD $) In Millions, unless otherwise specified | 0 Months Ended | 1 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  | 12 Months Ended |  | 12 Months Ended | 3 Months Ended | 12 Months Ended |  |  |  | 12 Months Ended
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Jan. 02, 2013 | Jan. 02, 2011 | Sep. 30, 2011 | Dec. 31, 2013 | Dec. 31, 2013 Reporting_Unit | Dec. 31, 2012 | Dec. 31, 2011 | Dec. 31, 2013 Alcoa Fastening Systems [Member] | Dec. 31, 2013 Alcoa Power and Propulsion [Member] | Dec. 31, 2013 Engineered Products and Solutions [Member] Reporting_Unit | Dec. 31, 2013 Alumina [Member] | Dec. 31, 2012 Alumina [Member] | Dec. 31, 2011 Alumina [Member] | Dec. 31, 2013 Alumina [Member] Primary Metals [Member] Reporting_Unit | Dec. 31, 2013 Primary Metals [Member] | Dec. 31, 2013 Primary Metals [Member] | Dec. 31, 2012 Primary Metals [Member] | Dec. 31, 2011 Primary Metals [Member] | Dec. 31, 2013 Maximum [Member] | Dec. 31, 2013 Maximum [Member] Bauxite Mining [Member] | Dec. 31, 2013 Minimum [Member] | Dec. 31, 2013 Minimum [Member] Bauxite Mining [Member]
Summary Of Significant Accounting Policies [Line Items] |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Percent of equity investments in other entity |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 50.00% |  |  |
Original maturity of cash equivalents |  |  |  |  | 3 months |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Period of mining |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 5 years |  | 1 year
Number of reporting units being subjected to goodwill impairment test |  |  |  |  | 9 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Number of reporting unit having maximum goodwill |  |  |  |  |  |  |  |  |  | 2 |  |  |  |  |  |  |  |  |  |  |  |
Number of reporting units |  |  |  |  |  |  |  |  |  | 5 |  |  |  | 4 |  |  |  |  |  |  |  |
Percentage of total goodwill allocated to reporting units |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 80.00% |
Goodwill |  |  |  | $ 3,415 | $ 3,415 | $ 5,170 | $ 5,157 | $ 1,166 | $ 1,617 |  | $ 9 | $ 10 | $ 11 |  |  |  | $ 997 | $ 991 |  |  |  |
Minimum percentage of estimated fair value of reporting unit to be less than carrying amount of goodwill |  |  |  |  | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Minimum number of reporting units being subjected for goodwill impairment test |  |  |  |  | 3 |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Qualitative assessment for reporting units |  |  |  |  | 7 |  |  |  |  | 4 |  |  |  |  |  |  |  |  |  |  |  |
Implied fair value of goodwill |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  | 0 |  |  |  |  |  |
Goodwill impairment |  |  |  | 1,731 | 1,731 |  |  |  |  |  |  |  |  |  | 1,731 | 989 |  |  |  |  |  |
Goodwill impairment after noncontrolling interest |  |  |  | $ 1,719 |  |  |  |  |  |  |  |  |  |  | $ 1,719 | $ 1,719 |  |  |  |  |  |
Estimated fair value of exceeded percentage on carrying value |  |  |  |  |  |  |  |  |  |  | 18.00% | 7.00% |  |  |  |  |  |  |  |  |  |
Maximum hedging contracts period, in years |  |  |  |  | 5 years |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Businesses expected to be disposed within, years |  |  |  |  | 1 year |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |
Goodwill impairment threshold, maximum | 50.00% | 50.00% | 50.00% |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |  |

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