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Stockholders' Equity - Schedule of Transactions from Employee Option and Share Plans (Detail) (USD $)
In Millions, except Share data, unless otherwise specified
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Equity, Class of Treasury Stock [Line Items]    
Total shares in treasury at beginning of year 3,915,144  
Total cost $ 57  
Shares acquired under repurchase program 1,843,694  
Average price in $ per share $ 21.70  
Amount paid 40 57
Shares delivered 3,032,838  
Average price in $ per share $ 12.97  
Amount received 15  
Total shares in treasury at end of year 2,726,000 3,915,144
Total cost $ 58 $ 57