v2.4.0.6
Securitizations and Variable Interest Entities, Key Economic Assumptions - Mortgage Servicing Assets (Details) (USD $)
3 Months Ended
Mar. 31, 2013
Mar. 31, 2012
Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Line Items]    
Prepayment speed (annual CPR) 11.90% 13.10%
Discount rate 7.10% 7.10%
Cost to service ($ per loan) $ 178 $ 119