Loans - Additional Information (Detail) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Net deferred origination costs	$ 30,000,000		$ 30,000,000		$ 48,000,000
Net unamortized premium on loans	29,000,000		29,000,000		28,000,000
Amortized net premiums on loans	2,000,000	10,000,000	20,000,000	38,000,000
Nonaccrual Loans	1,790,000,000		1,790,000,000		1,828,000,000
Current Interest income of nonaccrual loans	37,000,000	27,000,000	92,000,000	86,000,000
Current Interest income (expense) and other income included in finance for loans	10,000,000	4,000,000	10,000,000	13,000,000
Loans discharged under bankruptcy and not re-affirmed to residential mortgage TDR Loan balances	186,000,000
Closed end first lien loans held for sale	$ 500,000,000		$ 500,000,000		$ 2,000,000,000