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Securities (Schedule Of Cost And Estimated Fair Value Of Securities Available For Sale And Securities Held To Maturity By Contractual Maturity) (Detail) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Amortized Cost - Securities available for sale $ 26,597 $ 23,957
Due after five years through ten years, Amortized Cost     
Due after ten years, Amortized Cost     
Amortized Cost - Securities held to maturity 13 16
Securities available for sale: 27,232 24,471
Due after five years through ten years, Estimated Fair Value     
Due after ten years, Estimated Fair Value     
Estimated Fair Value - Securities held to maturity 14 17
Residential Agency [Member]
   
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Amortized Cost - Securities available for sale 22,923 21,688
Amortized Cost - Securities held to maturity 8 9
Securities available for sale: 23,494 22,175
Estimated Fair Value - Securities held to maturity 8 10
Residential Non-Agency [Member]
   
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Amortized Cost - Securities available for sale 13 15
Securities available for sale: 14 16
Commercial Agency [Member]
   
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Amortized Cost - Securities available for sale 499 318
Securities available for sale: 514 326
Commercial Non-Agency [Member]
   
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Amortized Cost - Securities available for sale 619 314
Securities available for sale: 637 321
Equity Securities [Member]
   
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Amortized Cost - Securities available for sale 722 817
Securities available for sale: 722 815
Securities Available For Sale [Member]
   
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Due in one year or less, Amortized Cost 27  
Due after one year through five years, Amortized Cost 636  
Due after five years through ten years, Amortized Cost 910  
Due after ten years, Amortized Cost 248  
Due in one year or less, Estimated Fair Value 27  
Due after one year through five years, Estimated Fair Value 641  
Due after five years through ten years, Estimated Fair Value 928  
Due after ten years, Estimated Fair Value 255  
Securities Held-to-maturity Securities [Member]
   
Contractual Maturity Of Securities Available For Sale And Securities Held To Maturity [Line Items]    
Due in one year or less, Amortized Cost 3  
Due after one year through five years, Amortized Cost 2  
Due in one year or less, Estimated Fair Value 3  
Due after one year through five years, Estimated Fair Value $ 3