v2.4.0.6
Securitizations and Variable Interest Entities, Key Economic Assumptions - Mortgage Servicing Assets (Details) (Residential Mortgage Servicing [Member], USD $)
3 Months Ended
Mar. 31, 2012
Mar. 31, 2011
Residential Mortgage Servicing [Member]
   
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]    
Prepayment speed (annual CPR) 13.10% 11.40%
Discount rate 7.10% 7.90%
Cost to service ($ per loan) $ 119 $ 134