v2.4.0.6
Loans and Allowance for Credit Losses, Loans by Credit Impairment Methodology (Details) (USD $)
In Millions, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Mar. 31, 2012
Dec. 31, 2011
Dec. 31, 2008
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]          
Allowance for Credit Losses, Collectively evaluated $ 11,350 $ 11,475      
Allowance for Credit Losses, Individually evaluated 5,763 5,885      
Allowance for Credit Losses, Purchased Credit-Impaired 80 117 245    
Total allowance for credit losses 17,193 17,477 19,129 19,668  
Financing Receivable, Collectively evaluated 739,849 738,594      
Financing Receivable, Individually evaluated 30,388 30,012      
Purchased Credit Impaired Loans 29,729 30,968     58,797
Loans 799,966 799,574      
Commercial Portfolio Segment [Member]
          
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]          
Allowance for Credit Losses, Collectively evaluated 4,200 3,951      
Allowance for Credit Losses, Individually evaluated 1,533 1,675      
Allowance for Credit Losses, Purchased Credit-Impaired 53 88      
Total allowance for credit losses 5,786 5,714 6,130 6,358  
Financing Receivable, Collectively evaluated 350,765 349,035      
Financing Receivable, Individually evaluated 7,447 8,186      
Purchased Credit Impaired Loans 3,502 3,977     18,704
Loans 361,714 361,198      
Consumer Portfolio Segment [Member]
          
Loans and Allowance for Credit Losses, by Credit Impairment Method [Abstract]          
Allowance for Credit Losses, Collectively evaluated 7,150 7,524      
Allowance for Credit Losses, Individually evaluated 4,230 4,210      
Allowance for Credit Losses, Purchased Credit-Impaired 27 29      
Total allowance for credit losses 11,407 11,763 12,999 13,310  
Financing Receivable, Collectively evaluated 389,084 389,559      
Financing Receivable, Individually evaluated 22,941 21,826      
Purchased Credit Impaired Loans 26,227 26,991     40,093
Loans $ 438,252 $ 438,376