Certain Transfers of Financial Assets and Variable Interest Entities Portfolio Balances and Delinquency Balances Based on 90 days or more Past Due and Net Charge-Offs Related to Managed Portfolio Loans (parenthetical) (Details) (USD $)	Mar. 31, 2013	Dec. 31, 2012
Servicing Assets at Fair Value [Line Items]
LHFS excluded from managed loans disclosure	$ 3,200,000,000	$ 3,400,000,000
Loans Held-for-Sale
Servicing Assets at Fair Value [Line Items]
LHFS Accruing90OrMoreDaysPastDueAndNonaccruing	$ 43,000,000	$ 38,000,000