v2.4.0.6
Short-term Borrowings (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Dec. 31, 2009
Short-term Debt [Line Items]      
Short-term borrowings, Amount $ 49,091 $ 55,401 $ 38,966
Short Term Borrowings, Rate 0.10% 0.19% 0.18%
Short term Debt average daily balance, Amount 51,781 46,824 51,972
Short term Debt average daily balance, Rate 0.18% 0.22% 0.44%
Federal Funds Purchased and Securities Sold under Agreements to Repurchase [Member]
      
Short-term Debt [Line Items]      
Short-term borrowings, Amount 31,038 37,947 26,016
Short Term Borrowings, Rate 0.05% 0.15% 0.08%
Short term Debt average daily balance, Amount 34,388 30,494 24,179
Short term Debt average daily balance, Rate 0.11% 0.18% 0.46%
Maximum month-end balance, Amount 37,509 37,947 30,608
Commercial Paper [Member]
      
Short-term Debt [Line Items]      
Short-term borrowings, Amount 18,053 17,454 12,950
Short Term Borrowings, Rate 0.19% 0.26% 0.39%
Short term Debt average daily balance, Amount 17,393 16,330 27,793
Short term Debt average daily balance, Rate 0.33% 0.31% 0.43%
Maximum month-end balance, Amount $ 18,234 $ 17,646 $ 62,871