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Stock-Based Compensation - Additional Information (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Long-term stock awards, including restoration options 1,000,000 1,000,000
Total unrecognized compensation expense $ 10 $ 19
Weighted average remaining vesting period in years 2 years 2 years
Total market value (at the vesting date) of stock award shares 38 27
Stock awards granted subsequent to January 1, 2010 have a vesting period, in years 4 years 5 years
Expiration date 6 years 6 years
Grant date exercise price per share $ 20 $ 12
Stock option shares forfeited 1,000,000 3,000,000
Unvested Awards [Member]
    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Total unrecognized compensation expense $ 76 $ 79
Weighted average remaining vesting period in years 3 years 4 years
Stock Option [Member]
    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Stock awards granted subsequent to January 1, 2010 have a vesting period, in years 5 years 5 years
Stock option shares granted 899,000  
Grant date exercise price per share $ 20  
Stock option shares forfeited 1,220,830  
Long-Term Stock Awards [Member]
    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Long-term stock awards, including restoration options 1,683,980  
Maximum [Member]
    
Deferred Compensation Arrangement with Individual, Share-based Payments [Line Items]    
Expiration date 10 years 10 years