Loans - Trouble Debt Restructuring Additional Information (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013		Dec. 31, 2012		Dec. 31, 2011
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	$ 1,374		$ 1,238		$ 1,034
Trouble debt restructuring interest income recognized	49		46		35
Commercial Loan [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	441		484		479
Trouble debt restructuring interest income recognized	15		12		14
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	349		360		346
Trouble debt restructuring interest income recognized	12		8		9
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	44		91		89
Trouble debt restructuring interest income recognized	0		0		0
Commercial Loan [Member] | Global Banking [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	20		0		0
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	28		33		44
Trouble debt restructuring interest income recognized	3		4		5
Consumer Loans [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	933		754		555
Trouble debt restructuring interest income recognized	34		34		21
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	922	[1]	738	[1]	532	[1]
Trouble debt restructuring interest income recognized	33		33		20
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Modifications [Line Items]
Trouble debt restructuring average recorded investment	11		16		23
Trouble debt restructuring interest income recognized	$ 1		$ 1		$ 1

[1] Beginning in the third quarter of 2012, average balances for residential mortgages include loans discharged under Chapter 7 bankruptcy and not re-affirmed.