Loans - Average Balance and Interest Income Recognized on Impaired Commercial Loans (Detail) (Commercial Loan [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Financing Receivable, Impaired [Line Items]
Total average balance of impaired commercial loans	$ 586	$ 893	$ 1,113
Total interest income recognized on impaired commercial loans	18	19	17
Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Total average balance of impaired commercial loans	422	602	744
Total interest income recognized on impaired commercial loans	13	11	9
Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
Total average balance of impaired commercial loans	63	119	151
Total interest income recognized on impaired commercial loans	0	5	4
Global Banking [Member]
Financing Receivable, Impaired [Line Items]
Total average balance of impaired commercial loans	37	86	107
Total interest income recognized on impaired commercial loans	0	0	1
Other Commercial [Member]
Financing Receivable, Impaired [Line Items]
Total average balance of impaired commercial loans	64	86	111
Total interest income recognized on impaired commercial loans	$ 5	$ 3	$ 3