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		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Financing Receivable, Impaired [Line Items]
Total	$ 59	$ 87	$ 105	$ 134
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
Total	11	37	21	41
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Total	0	32	0	32
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
Total	11	5	11	9
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Impaired [Line Items]
Total	0	0	10	0
Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
Total	48	50	84	93
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
Total	47	49	81	92
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Impaired [Line Items]
Total	$ 1	$ 1	$ 3	$ 1