Asset Quality - Additional Information (Detail) (USD $)	12 Months Ended				3 Months Ended		12 Months Ended
	Dec. 31, 2012 SecurityLoan	Dec. 31, 2011 SecurityLoan	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2012 PCI Loans [Member]	Dec. 31, 2012 Purchase Credit Impaired Loans [Member]	Dec. 31, 2012 Secured Loans at Banks [Member]
Estimated gross contractual amount receivable of PCI loans	$ 41
Estimated cash flows nonaccretable amount	11,000,000
Estimated cash flows accretable amount	5,000,000
Purchased credit impaired loans	23,000,000				31,000,000
Purchased credit impaired loans carrying value					23,000,000
Changes in the accretable yield, accretion	1,000,000
Changes in the accretable yield, net reclassifications	1,000,000
Accretable yield	4,000,000
Percentage of carrying amount of our commercial nonperforming loans outstanding	57.00%
Percentage of nonperforming loans outstanding face value	73.00%
Percentage of loans held for sale and other nonperforming assets	70.00%
Aggregate carrying amount of largest nonperforming loans	179,000,000
Number of largest nonperforming loans	20	20
Total loans on nonperforming status from continuing operations		237,000,000
Percentage of total loans on nonperforming status	27.00%	33.00%
Net reduction to interest income	25,000,000	31,000,000
Interest income recognized on outstanding balances	5,000,000	4,000,000
Total restructured loans	320,000,000	276,000,000
Addition in restructured loans	284,000,000
Restructured loans partially in payments and charge-offs	240,000,000
Trial period HAMP loans included in TDR amounts	4,000,000
Secured loans discharged	72,000,000						72,000,000
Total current loan	51,623,000,000	48,243,000,000
Percent of total current loan	97.80%
Total past due loan	1,176,000,000	1,332,000,000
Percent of total past due loans	2.20%
Minimum outstanding impaired commercial loans	2,500,000
Number of days to designate commercial loans will be charged off in full or charged down to the fair value of the underlying collateral payment due period	180 days
Number of days to designate the charge-off policy for most consumer loans taking effect, payment due period	120 days
Number of days to designate home equity and residential mortgage loans to get charged down to the fair value of the underlying collateral payment due period	180 days
ALLL	888,000,000	1,004,000,000
ALLL percentage	1.68%	2.03%
ALLL of nonperforming loans percentage	131.75%	138.10%
Increase (decrease) in allowance for loan losses	116,000,000
Percentage decrease in allowance for loan losses	12.00%
Corresponding allowance	35,000,000	51,000,000			1,000,000
Individually evaluated for impairment corresponding allowance	411,000,000	388,000,000
Collectively Evaluated for Impairment, Outstanding	52,388,000,000	49,187,000,000				23,000,000
Collectively evaluated for current corresponding allowance	852,000,000
Provision for loan and lease losses	(229,000,000)	59,000,000			1,000,000
Increase decrease liability for credit losses on lending related commitments		16,000,000
Percentage of total allowance for credit losses	1.74%	2.12%
Liability for credit losses on lending-related commitments	$ 29,000,000	$ 45,000,000	$ 73,000,000	$ 121,000,000