Loans - Loans Classified as TDR Loans (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	$ 58	$ 113
Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	14	27
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	12	27
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	2	0
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	0	0
Consumer Loans [Member]
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	44	86
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	44	86
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Modifications [Line Items]
TDR loans during previous months which became contractually delinquent	$ 0	$ 0