Loans - Status of Commercial Loan Portfolio (Detail) (USD $)	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Recorded Investment [Line Items]
Nonaccrual Loans	$ 1,305,000,000	$ 1,629,000,000
Accruing Loans Contractually Past Due 90 days or More	44,000,000	80,000,000
Total loans	67,695,000,000	63,258,000,000	51,867,000,000
Commercial Loan [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	48,234,000,000	43,650,000,000
Nonaccrual Loans	254,000,000	463,000,000
Accruing Loans Contractually Past Due 90 days or More	6,000,000	37,000,000
Total loans	48,494,000,000	44,150,000,000
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	8,868,000,000	8,064,000,000
Nonaccrual Loans	166,000,000	385,000,000
Accruing Loans Contractually Past Due 90 days or More	0	8,000,000
Total loans	9,034,000,000	8,457,000,000	7,860,000,000
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	14,420,000,000	12,533,000,000
Nonaccrual Loans	21,000,000	47,000,000
Accruing Loans Contractually Past Due 90 days or More	5,000,000	28,000,000
Total loans	14,446,000,000	12,608,000,000	10,225,000,000
Commercial Loan [Member] | Global Banking [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	21,560,000,000	19,991,000,000
Nonaccrual Loans	65,000,000	18,000,000
Accruing Loans Contractually Past Due 90 days or More	0	0
Total loans	21,625,000,000	20,009,000,000	12,658,000,000
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Recorded Investment [Line Items]
Performing Loans	3,386,000,000	3,062,000,000
Nonaccrual Loans	2,000,000	13,000,000
Accruing Loans Contractually Past Due 90 days or More	1,000,000	1,000,000
Total loans	$ 3,389,000,000	$ 3,076,000,000	$ 2,906,000,000