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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
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%