Loans - Delinquency Ratio for Consumer Loan (Detail) (Consumer Loans [Member], USD $) In Millions, unless otherwise specified	Dec. 31, 2014		Dec. 31, 2013
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	$ 1,103		$ 1,316
Delinquency Ratio	5.59%		6.80%
Total residential mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	1,075	[1]	1,276	[1]
Delinquency Ratio	5.82%	[1]	7.11%	[1]
Residential Mortgage [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	1,013		1,208
Delinquency Ratio	6.07%		7.59%
Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	62		68
Delinquency Ratio	3.48%		3.38%
Credit Cards [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	14		21
Delinquency Ratio	1.94%		2.46%
Other consumer [Member]
Financing Receivable, Recorded Investment [Line Items]
Delinquent Loans	$ 14		$ 19
Delinquency Ratio	2.52%		3.32%

[1] At December 31, 2014 and 2013, residential mortgage loan delinquency includes $936 million and $1,074 million, respectively, of loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell.