Loans - Status of Consumer Loan Portfolio (Detail) - USD ($) $ in Millions		Sep. 30, 2015	Dec. 31, 2014	Sep. 30, 2014
Financing Receivable, Recorded Investment [Line Items]
Accruing Loans Contractually Past Due 90 days or More		$ 20	$ 21
Total loans		84,942	77,741	$ 73,439
Consumer Loans [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		19,314	18,719
Nonaccrual Loans		857	915
Accruing Loans Contractually Past Due 90 days or More		19	20
Total loans		20,190	19,654
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		16,670	15,814
Nonaccrual Loans	[1],[2],[3]	790	847
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		17,460	16,661	16,402
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		1,572	1,716
Nonaccrual Loans	[1],[3]	67	68
Accruing Loans Contractually Past Due 90 days or More		0	0
Total loans		1,639	1,784	1,824
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		673	710
Nonaccrual Loans		0	0
Accruing Loans Contractually Past Due 90 days or More		9	10
Total loans		682	720	686
Consumer Loans [Member] | Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans		399	479
Nonaccrual Loans	[1],[3]	0	0
Accruing Loans Contractually Past Due 90 days or More		10	10
Total loans		$ 409	$ 489	$ 465

[1] At September 30, 2015 and December 31, 2014, nonaccrual consumer mortgage loans include $740 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.

[2] 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.

[3] 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.