Loans - Delinquency Ratio for Consumer Loan (Detail) (Consumer Loans [Member], USD $) In Millions, unless otherwise specified	Sep. 30, 2013		Dec. 31, 2012
Financing Receivable, Recorded Investment [Line Items]
Dollars of Delinquency	$ 1,342		$ 1,359
Delinquency Ratio	6.92%		6.92%
Total residential mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Dollars of Delinquency	1,296		1,308
Delinquency Ratio	7.23%		7.20%
Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Dollars of Delinquency	1,221	[1]	1,233	[1]
Delinquency Ratio	7.70%	[1]	7.78%	[1]
Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Dollars of Delinquency	75		75
Delinquency Ratio	3.61%		3.23%
Credit Card Receivables [Member]
Financing Receivable, Recorded Investment [Line Items]
Dollars of Delinquency	18		21
Delinquency Ratio	2.10%		2.58%
Other Consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Dollars of Delinquency	$ 28		$ 30
Delinquency Ratio	4.65%		4.52%

[1] At September 30, 2013 and December 31, 2012, residential mortgage loan delinquency includes $1.1 billion and $1.0 billion, respectively, of loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell.