Loans - Impaired Commercial Loans Considered as TDR Loans (Parenthetical) (Detail) (USD $) In Millions, unless otherwise specified	Mar. 31, 2014		Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
TDR Loans	$ 1,211	[1],[2],[3]	$ 1,370	[1],[2],[3]
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	263	[2],[3]	389	[2],[3]
Unpaid principal balance of impaired commercial loans	380		641
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	236	[2],[3]	292	[2],[3]
Unpaid principal balance of impaired commercial loans	289		380
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	17	[2],[3]	21	[2],[3]
Unpaid principal balance of impaired commercial loans	71		91
Commercial Loan [Member] | Global Banking [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	0	[2],[3]	51	[2],[3]
Unpaid principal balance of impaired commercial loans	0		123
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	10	[2],[3]	25	[2],[3]
Unpaid principal balance of impaired commercial loans	$ 20		$ 47

[1] Includes $362 million and $458 million at March 31, 2014 and December 31, 2013, respectively, of loans which are classified as nonaccrual.

[2] The TDR Loan balances included in the table above reflect the current carrying amount of TDR Loans and includes all basis adjustments on the loan, such as unearned income, unamortized deferred fees and costs on originated loans, partial charge-offs and premiums or discounts on purchased loans. The following table reflects the unpaid principal balance of TDR Loans:March 31, 2014 December 31, 2013 (in millions)Commercial loans: Construction and other real estate$256 $309Business and corporate banking48 60Global banking— 51Other commercial10 28Total commercial314 448Consumer loans: Residential mortgages1,121 1,153Credit cards9 8Total consumer1,130 1,161Total$1,444 $1,609

[3] TDR Loans are considered to be impaired loans. For consumer loans, all such loans are considered impaired loans regardless of accrual status. For commercial loans, impaired loans include other loans in addition to TDR Loans which totaled $46 million and $92 million at March 31, 2014 and December 31, 2013, respectively.