Loans - Status of Consumer Loan Portfolio (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2015		Dec. 31, 2014		Mar. 31, 2014
Financing Receivable, Recorded Investment [Line Items]
Accruing Loans Contractually Past Due 90 days or More	$ 20		$ 21
Total loans	81,458		77,741		68,897
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	18,922		18,719
Nonaccrual loans	870		915
Accruing Loans Contractually Past Due 90 days or More	19		20
Total loans	19,811		19,654
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	16,188		15,814
Nonaccrual loans	803	[1],[2],[3]	847	[1],[2],[3]
Accruing Loans Contractually Past Due 90 days or More	0		0
Total loans	16,991		16,661		15,900
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	1,649		1,716
Nonaccrual loans	67	[1],[2]	68	[1],[2]
Accruing Loans Contractually Past Due 90 days or More	0		0
Total loans	1,716		1,784		1,938
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	670		710
Nonaccrual loans	0		0
Accruing Loans Contractually Past Due 90 days or More	10		10
Total loans	680		720		683
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	415		479
Nonaccrual loans	0		0
Accruing Loans Contractually Past Due 90 days or More	9		10
Total loans	$ 424		$ 489		$ 483

[1] Nonaccrual consumer mortgage loans include all receivables which are 90 or more days contractually delinquent as well as loans discharged under Chapter 7 bankruptcy and not re-affirmed and second lien loans where the first lien loan that we own or service is 90 or more days contractually delinquent.

[2] At March 31, 2015 and December 31, 2014, nonaccrual consumer mortgage loans include $760 million and $817 million, respectively, of loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell.

[3] Nonaccrual consumer mortgage loans for all periods does not include guaranteed loans purchased from the Government National Mortgage Association ("GNMA"). Repayment of these loans are predominantly insured by the Federal Housing Administration and as such, these loans have different risk characteristics from the rest of our consumer loan portfolio.