v2.4.0.6
Fair Value, Estimates for Financial Instruments Not Carried at Fair Value (Details) (USD $)
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Dec. 31, 2008
Financial assets:          
Cash and due from banks $ 21,860,000,000 $ 19,440,000,000 $ 16,044,000,000 $ 27,080,000,000  
Federal funds sold, securities purchased under resale agreements and other short-term investments 137,313,000,000 44,367,000,000      
Mortgages held for sale 47,149,000,000 48,357,000,000      
Loans held for sale 110,000,000 1,338,000,000      
Loans 799,574,000,000 769,631,000,000 757,267,000,000 782,770,000,000 864,830,000,000
Nonmarketable equity investments (cost method) 6,799,000,000 8,061,000,000      
Financial liabilities:          
Deposits 1,002,835,000,000 920,070,000,000      
Short-term borrowings 57,175,000,000 49,091,000,000 55,401,000,000    
Long-term debt 127,379,000,000 125,354,000,000      
Carrying amount [Member]
          
Financial assets:          
Cash and due from banks 21,860,000,000 19,440,000,000      
Federal funds sold, securities purchased under resale agreements and other short-term investments 137,313,000,000 44,367,000,000      
Mortgages held for sale 4,844,000,000 3,566,000,000      
Loans held for sale 104,000,000 162,000,000      
Loans 763,968,000,000 731,308,000,000      
Nonmarketable equity investments (cost method) 6,799,000,000 8,061,000,000      
Financial liabilities:          
Deposits 1,002,835,000,000 920,070,000,000      
Short-term borrowings 57,175,000,000 49,091,000,000      
Long-term debt 127,366,000,000 125,238,000,000      
Estimated fair value [Member]
          
Financial assets:          
Cash and due from banks 21,860,000,000 19,440,000,000      
Federal funds sold, securities purchased under resale agreements and other short-term investments 137,313,000,000 44,367,000,000      
Mortgages held for sale 4,853,000,000 3,566,000,000      
Loans held for sale 112,000,000 176,000,000      
Loans 772,351,000,000 723,867,000,000      
Nonmarketable equity investments (cost method) 8,231,000,000 8,490,000,000      
Financial liabilities:          
Deposits 1,003,942,000,000 921,803,000,000      
Short-term borrowings 57,175,000,000 49,091,000,000      
Long-term debt 130,283,000,000 126,484,000,000      
Estimated fair value [Member] | Level 1 [Member]
          
Financial assets:          
Cash and due from banks 21,860,000,000        
Federal funds sold, securities purchased under resale agreements and other short-term investments 5,046,000,000        
Mortgages held for sale 0        
Loans held for sale 0        
Loans 0        
Nonmarketable equity investments (cost method) 0        
Financial liabilities:          
Deposits 0        
Short-term borrowings 0        
Long-term debt 0        
Estimated fair value [Member] | Level 2 [Member]
          
Financial assets:          
Cash and due from banks 0        
Federal funds sold, securities purchased under resale agreements and other short-term investments 132,267,000,000        
Mortgages held for sale 3,808,000,000        
Loans held for sale 83,000,000        
Loans 56,237,000,000        
Nonmarketable equity investments (cost method) 2,000,000        
Financial liabilities:          
Deposits 946,922,000,000        
Short-term borrowings 57,175,000,000        
Long-term debt 119,220,000,000        
Estimated fair value [Member] | Level 3 [Member]
          
Financial assets:          
Cash and due from banks 0        
Federal funds sold, securities purchased under resale agreements and other short-term investments 0        
Mortgages held for sale 1,045,000,000        
Loans held for sale 29,000,000        
Loans 716,114,000,000        
Nonmarketable equity investments (cost method) 8,229,000,000        
Financial liabilities:          
Deposits 57,020,000,000        
Short-term borrowings 0        
Long-term debt $ 11,063,000,000