Loans - Summary of Receivables which were Modified and as Result Became Classified as TDR Loans (Detail) (USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012
Financing Receivable, Impaired [Line Items]
Total	$ 346	$ 555
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Total	114	99
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Total	59	78
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
Total	4	21
Commercial Loan [Member] | Global Banking [Member]
Financing Receivable, Impaired [Line Items]
Total	51	0
Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Total	232	456
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Total	230	452
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Impaired [Line Items]
Total	$ 2	$ 4