Quarterly report pursuant to Section 13 or 15(d)

Securities - U.S. GSE, Agency, and Treasury Securities (Details)

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Securities - U.S. GSE, Agency, and Treasury Securities (Details) (USD $)
In Millions, unless otherwise specified
Jun. 30, 2012
Dec. 31, 2011
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity debt securities, Amortized Cost $ 35,168 [1] $ 35,265 [1]
Held-to-maturity Securities, Fair Value 35,994 [1] 35,442 [1]
Federal National Mortgage Association Certificates and Obligations (FNMA) [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity debt securities, Amortized Cost 124,130 87,898
Held-to-maturity Securities, Fair Value 126,482 89,243
Government National Mortgage Association Certificates and Obligations (GNMA) [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity debt securities, Amortized Cost 111,777 102,960
Held-to-maturity Securities, Fair Value 114,508 106,200
Federal Home Loan Mortgage Corporation Certificates and Obligations (FHLMC) [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity debt securities, Amortized Cost 26,981 26,617
Held-to-maturity Securities, Fair Value 27,517 27,129
United States Treasury Securities Exceeding Ten Percent Of Consolidated Shareholders Equity [Member]
    
Schedule of Held-to-maturity Securities [Line Items]    
Held-to-maturity debt securities, Amortized Cost 29,630 39,946
Held-to-maturity Securities, Fair Value $ 29,427 $ 39,164
[1] Substantially all U.S. agency mortgage-backed securities.