Loans - Summary of Receivables which were Modified and as Result Became Classified as TDR Loans (Detail) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Financing Receivable, Impaired [Line Items]
Total	$ 46	$ 48
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Total	10	4
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
Total	10	4
Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Total	36	44
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Total	34	44
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Impaired [Line Items]
Total	$ 2	$ 0