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
Mar. 31, 2013
Dec. 31, 2012
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Total Assets $ 577,586 $ 602,928
Short-term borrowings 2,509 3,376
Due to Related Parties 10,042 8,752
Total Liabilities 513,265 538,528
Weighted Average Remaining Life of Bonds Held in Trusts 11 years 4 months 24 days  
Municipal Bond Trusts [Member]
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Maximum loss exposure 965 1,454
Municipal Bond Trusts [Member] | Consolidated VIE
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Maximum loss exposure 778 1,348
Municipal Bond Trusts [Member] | Unconsolidated VIEs
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Maximum loss exposure 187 106
Liquidity commitments to unconsolidated municipal bond trusts 92 106
Municipal Bond Trusts [Member]
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Short-term borrowings 1,755 2,859
Due to Related Parties 1,103 1,157
Total Liabilities 2,858 4,016
Municipal Bond Trusts [Member] | Consolidated VIE
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Short-term borrowings 1,755 2,859
Due to Related Parties 1,103 1,157
Total Liabilities 2,858 4,016
Municipal Bond Trusts [Member] | Unconsolidated VIEs
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Short-term borrowings 0 0
Due to Related Parties 0 0
Total Liabilities 0 0
Municipal Bond Trusts [Member]
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Trading assets 1,976 2,505
Total Assets 1,976 2,505
Total assets of VIEs 2,212 2,638
Municipal Bond Trusts [Member] | Consolidated VIE
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Trading assets 1,881 2,505
Total Assets 1,881 2,505
Total assets of VIEs, consolidated 1,881 2,505
Municipal Bond Trusts [Member] | Unconsolidated VIEs
   
Summary Of Information Related To Municipal Bond Trusts [Abstract]    
Trading assets 95 0
Total Assets 95 0
Total assets of VIEs, unconsolidated $ 331 $ 133