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 (Additional Information) (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Servicing Assets at Fair Value [Line Items]
Cash Flows Between Transferor and Transferee, Receipts on Transferor's Interest in Transferred Financial Assets, Other	$ 21,000,000	$ 36,000,000	$ 30,000,000
LHFS excluded from managed loans disclosure	3,200,000,000	1,700,000,000
Loans Held For Sale [Member]
Servicing Assets at Fair Value [Line Items]
LHFS Accruing90OrMoreDaysPastDueAndNonaccruingExcludedFromManagedLoanDisclosure	$ 39,000,000	$ 17,000,000