Asset Quality - Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014 SecurityLoan	Dec. 31, 2013 SecurityLoan	Dec. 31, 2012	Dec. 31, 2011
Accounts, Notes, Loans and Financing Receivable [Line Items]
Estimated gross contractual amount receivable of PCI loans	$ 41
Estimated cash flows nonaccretable amount	11
Estimated cash flows accretable amount	5
Purchased Credit Impaired, Outstanding	13	16
Accretable yield	5
Percentage of carrying amount of our commercial nonperforming loans outstanding	74.00%
Percentage of nonperforming loans outstanding face value	79.00%
Percentage of loans held for sale and other nonperforming assets	79.00%
Aggregate carrying amount of largest nonperforming loans		86
Number of largest nonperforming loans	20	20
Total loans on nonperforming status from continuing operations	88
Percentage of total loans on nonperforming status	21.00%	17.00%
Net reduction to interest income	16	23
Interest income recognized on outstanding balances	7	6	5
Total restructured loans	270	338
Addition in restructured loans	93
Restructured loans partially in payments and charge-offs	161
Minimum outstanding impaired commercial loans	2.5
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
Number of days to designate the charge-off policy for credit card loans taking effect, payment due period	180 days
ALLL	794	848
ALLL percentage	1.38%	1.56%
ALLL of nonperforming loans percentage	190.00%	166.90%
Increase (decrease) in allowance for loan losses	54
Percentage decrease in allowance for loan losses	6.40%
Individually evaluated for impairment, outstanding	302	358
Individually evaluated for Impairment, corresponding allowance	40	42
Collectively Evaluated for Impairment, Outstanding	57,066.0	54,083.0
Collectively evaluated for current, corresponding allowance	753	805
Provision (credit) for loan and lease losses	59	130	229
Liability for credit losses on lending-related commitments	36	37	29	45
Percentage of total allowance for credit losses	1.45%	1.63%
Commercial Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Outstanding	1	1
Nature of default in repayment of loan TDRs	90 days past due
Individually evaluated for impairment, outstanding	72	127
Individually evaluated for Impairment, corresponding allowance	12	10
Collectively Evaluated for Impairment, Outstanding	41,308.0	38,199.0
Collectively evaluated for current, corresponding allowance	611	611
Consumer Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Outstanding	12	15
Nature of default in repayment of loan TDRs	More than 60 days past due
Number of loans	84	672
Financial receivable, modifications, subsequent default, recorded investment	4	31
Individually evaluated for impairment, outstanding	230	231
Individually evaluated for Impairment, corresponding allowance	28	32
Collectively Evaluated for Impairment, Outstanding	15,758.0	15,884.0
Collectively evaluated for current, corresponding allowance	142	194
Purchase Credit Impaired Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Individually evaluated for Impairment, corresponding allowance	1	1
Collectively Evaluated for Impairment, Outstanding	13.0	16.0
Provision (credit) for loan and lease losses	0	0
Maximum [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Changes in the accretable yield, accretion	1
Changes in the accretable yield, net reclassifications	1
Collectively Evaluated for Impairment, Outstanding	2.5
Performing [Member] | Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total current loan	56,600
Concentration risk	98.70%
Nonperforming [Member] | Accounts Receivable [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total current loan	749
Concentration risk	1.30%
PCI Loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Purchased Credit Impaired, Outstanding	20
Purchased credit impaired loans carrying value	$ 13