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Stockholders' Equity And Accumulated Other Comprehensive Income (Loss) (Narrative) (Detail) (USD $)
 1 Months Ended 3 Months Ended 6 Months Ended 1 Months Ended
Mar. 19, 2012
Nov. 14, 2008
Jun. 30, 2012
Jun. 30, 2012
Dec. 31, 2011
Mar. 31, 2011
May 31, 2012
Additional Paid-in Capital [Member]
Apr. 04, 2012
Series A Preferred Stock [Member]
Jun. 30, 2012
Series A Preferred Stock [Member]
Dec. 31, 2011
Series A Preferred Stock [Member]
Stockholders' Equity And Comprehensive Income (Loss) [Line Items]                    
Common stock, issued 153,000,000   1,454,542,017 1,454,542,017 1,301,230,838          
Common stock price per share $ 5.90                  
Net proceeds from issuance of common stock $ 875,000,000     $ 875,000,000            
Sale of Fixed Rate Cumulative Perpetual Preferred Stock, Series A   3,500,000             0 3,500,000
Preferred stock quarterly dividend rate during the first five years   5.00%                
Capital Purchase Program annual dividend   175,000,000                
Preferred stock quarterly dividend rate, after five years unless redeemed   9.00%                
Common shares issuable related to the U.S. Treasury warrant   48,300,000                
Exercise price per common share related to the U.S. Treasury warrant   10.88                
Total fair value of series A preferred shares and warrant   3,500,000,000                
Fair value allocated to preferred shares issued   3,304,000,000                
Fair value allocated to warrant   196,000,000                
Repurchased shares of Series A preferred stock               3,500,000    
Derecognized carrying value of Series A shares         3,419,000,000       3,419,000,000  
Discount accretion on preferred shares     71,000,000              
Repurchased warrant from U.S. Treasury Department             $ 45,000,000      
Common shares available for repurchase       23,100,000            
Annual cash dividend declared per common share     $ 0.01 $ 0.01   $ 0.01