v2.4.0.6
Securitizations and Variable Interest Entities, Key Economic Assumptions - Mortgage Servicing Rights (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 12 Months Ended
Mar. 31, 2012
years
Dec. 31, 2011
years
Residential Mortgage Servicing [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 $ 13,578 $ 12,918
Expected weighted-average life (in years) 5.2 5.1
Prepayment speed assumption (annual CPR) 14.50% 14.80%
Decrease in fair value from 10% adverse change 858 895
Decrease in fair value from 25% adverse change 2,018 2,105
Discount rate assumption 7.50% 7.10%
Decrease in fair value from 100 basis point increase 666 566
Decrease in fair value from 200 basis point increase 1,273 1,081
Cost to service assumption ($ per loan) 210 218
Decrease in fair value from 10% adverse change 575 582
Decrease in fair value from 25% adverse change 1,438 1,457
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 219 230
Expected weighted-average life (in years) 4.5 4.6
Prepayment speed assumption (annual CPR) 10.10% 10.70%
Decrease in fair value from 10% adverse change 6 6
Decrease in fair value from 25% adverse change 13 15
Discount rate assumption 16.00% 15.60%
Decrease in fair value from 100 basis point increase 5 6
Decrease in fair value from 200 basis point increase 11 12
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 317 321
Expected weighted-average life (in years) 5.9 5.6
Prepayment speed assumption (annual CPR) 12.70% 13.90%
Decrease in fair value from 10% adverse change 1 2
Decrease in fair value from 25% adverse change 3 4
Discount rate assumption 6.40% 7.10%
Decrease in fair value from 100 basis point increase 13 12
Decrease in fair value from 200 basis point increase 25 24
Credit loss assumption 3.70% 4.50%
Decrease in fair value from 10% higher losses 1 1
Decrease in fair value from 25% higher losses 1 2
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 45
Expected weighted-average life (in years) 6.1 6.1
Prepayment speed assumption (annual CPR) 6.90% 6.90%
Decrease in fair value from 10% adverse change 0 0
Decrease in fair value from 25% adverse change 0 1
Discount rate assumption 9.00% 11.90%
Decrease in fair value from 100 basis point increase 2 2
Decrease in fair value from 200 basis point increase 4 4
Credit loss assumption 0.40% 0.50%
Decrease in fair value from 10% higher losses 0 0
Decrease in fair value from 25% higher losses $ 0 $ 0