v2.4.0.6
Securitizations and Variable Interest Entities, Key Economic Assumptions - Mortgage Servicing Rights (Details) (USD $)
In Millions, unless otherwise specified
 12 Months Ended
Dec. 31, 2011
Dec. 31, 2010
Mortgage servicing rights [Member]
    
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]    
Fair value of interests held $ 14,359 $ 16,279
Expected weighted-average life (in years) 5.0 5.2
Prepayment speed assumption (annual CPR) 13.70% 12.60%
Decrease in fair value from 10% adverse change 913 844
Decrease in fair value from 25% adverse change 2,151 1,992
Discount rate assumption 6.90% 8.10%
Decrease in fair value from 100 basis point increase 613 777
Decrease in fair value from 200 basis point increase 1,171 1,487
Interest-Only Strips [Member]
    
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]    
Fair value of interests held 230 226
Expected weighted-average life (in years) 4.6 5.2
Prepayment speed assumption (annual CPR) 10.70% 11.40%
Decrease in fair value from 10% adverse change 6 7
Decrease in fair value from 25% adverse change 15 16
Discount rate assumption 15.60% 17.80%
Decrease in fair value from 100 basis point increase 6 6
Decrease in fair value from 200 basis point increase 12 13
Senior bonds [Member]
    
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]    
Fair value of interests held 321 441
Expected weighted-average life (in years) 5.6 4.5
Prepayment speed assumption (annual CPR) 13.90% 18.10%
Decrease in fair value from 10% adverse change 2 2
Decrease in fair value from 25% adverse change 4 6
Discount rate assumption 7.10% 6.80%
Decrease in fair value from 100 basis point increase 12 14
Decrease in fair value from 200 basis point increase 24 27
Credit loss assumption 4.50% 3.70%
Decrease in fair value from 10% higher losses 1 1
Decrease in fair value from 25% higher losses 2 3
Subordinated bonds [Member]
    
Sensitivity Analysis of Fair Value of Interests Continued to be Held by Transferor, Servicing Assets or Liabilities, Impact of Adverse Change in Assumption [Line Items]    
Fair value of interests held 45 47
Expected weighted-average life (in years) 6.1 8.3
Prepayment speed assumption (annual CPR) 6.90% 4.80%
Decrease in fair value from 10% adverse change 0 0
Decrease in fair value from 25% adverse change 1 0
Discount rate assumption 11.90% 10.20%
Decrease in fair value from 100 basis point increase 2 3
Decrease in fair value from 200 basis point increase 4 6
Credit loss assumption 0.50% 0.70%
Decrease in fair value from 10% higher losses 0 0
Decrease in fair value from 25% higher losses $ 0 $ 0