Quarterly report pursuant to Section 13 or 15(d)

Securitizations and Other Variable Interest Entities - Municipal Bond Trusts (Details)

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Securitizations and Other Variable Interest Entities - Municipal Bond Trusts (Details) (USD $)
In Millions, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2012
Sep. 30, 2011
Sep. 30, 2012
Sep. 30, 2011
Dec. 31, 2011
Variable Interest Entity [Line Items]          
Weighted Average Remaining Life of Bonds Held in Trusts     9 years 3 months 18 days    
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Total Assets $ 595,379   $ 595,379   $ 556,463
Short-term borrowings 3,556   3,556   6,051
Total Liabilities 546,226   546,226   506,495
Municipal Bond Trusts [Member]
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Maximum loss exposure 3,641   3,641   4,633
Municipal Bond Trusts [Member] | Consolidated VIE
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Maximum loss exposure 2,839   2,839   3,713
Municipal Bond Trusts [Member] | Unconsolidated VIEs
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Maximum loss exposure 802   802   920
Cash Flows Between Transferor and Transferee, Proceeds from New Transfers 69 182 268 509  
Principal balance outstanding for unconsolidated municipal bond securitization trusts 973   973   1,200
Liquidity commitments to unconsolidated municipal bond trusts 764   764   742
Municipal Bond Trusts [Member]
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Total Assets 1,184   1,184   0
Short-term borrowings 2,732   2,732   4,939
Total Liabilities 3,916   3,916   4,939
Municipal Bond Trusts [Member] | Consolidated VIE
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Total Assets 1,184   1,184   0
Short-term borrowings 2,732   2,732   4,939
Total Liabilities 3,916   3,916   4,939
Municipal Bond Trusts [Member] | Unconsolidated VIEs
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Total Assets 0   0   0
Short-term borrowings 0   0   0
Total Liabilities 0   0   0
Municipal Bond Trusts [Member]
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Trading assets 2,877   2,877   3,891
Total Assets 2,877   2,877   3,891
Total assets of VIEs 3,812   3,812   4,867
Municipal Bond Trusts [Member] | Consolidated VIE
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Trading assets 2,839   2,839   3,713
Total Assets 2,839   2,839   3,713
Total assets of VIEs, consolidated 2,839   2,839   3,713
Municipal Bond Trusts [Member] | Unconsolidated VIEs
         
Summary Of Information Related To Municipal Bond Trusts [Abstract]          
Trading assets 38   38   178
Total Assets 38   38   178
Total assets of VIEs, unconsolidated $ 973   $ 973   $ 1,154