Loans - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
Loans Receivable, Net [Abstract]
Net deferred origination costs		$ 30	$ 48
Net unamortized premium on loans		25	28
Amortized net premiums on loans		23	35	20
Nonaccrual Loans		1,629	1,828
Current Interest income of nonaccrual loans		125	117
Current Interest income (expense) and other income included in finance for loans		17	19
Additional residential mortgage loans as TDR loans	51
Credit loss reserves associated with residential mortgage loans	10
Incremental loan loss provision recorded using discounted cash flow analysis	7
Additional credit card loans as TDR loans	1
Credit loss reserves associated with credit card loans, less than $1 million	1
Commercial loans removed from TDR classification		$ 11