Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans (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]
Allowance for credit losses on TDR Loans	72	[4]	87	[4]
Unpaid Principal Balance of TDR Loans	1,444		1,609
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	263	[2],[3]	389	[2],[3]
Allowance for credit losses on TDR Loans	8	[4]	17	[4]
Unpaid Principal Balance of TDR Loans	314		448
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	236	[2],[3]	292	[2],[3]
Allowance for credit losses on TDR Loans	7	[4]	16	[4]
Unpaid Principal Balance of TDR Loans	256		309
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	17	[2],[3]	21	[2],[3]
Allowance for credit losses on TDR Loans	1	[4]	1	[4]
Unpaid Principal Balance of TDR Loans	48		60
Commercial Loan [Member] | Global Banking [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	0	[2],[3]	51	[2],[3]
Unpaid Principal Balance of TDR Loans	0		51
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	10	[2],[3]	25	[2],[3]
Unpaid Principal Balance of TDR Loans	10		28
Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	948	[2],[3]	981	[2],[3]
Allowance for credit losses on TDR Loans	64	[4]	70	[4]
Unpaid Principal Balance of TDR Loans	1,130		1,161
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	939	[2],[3],[5]	973	[2],[3],[5]
Allowance for credit losses on TDR Loans	62	[4]	68	[4]
Unpaid Principal Balance of TDR Loans	1,121		1,153
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	9	[2],[3]	8	[2],[3]
Allowance for credit losses on TDR Loans	2	[4]	2	[4]
Unpaid Principal Balance of TDR Loans	$ 9		$ 8

[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.

[4] Included in the allowance for credit losses.

[5] Includes $718 million and $706 million at March 31, 2014 and December 31, 2013, respectively, of loans that are recorded at the lower of amortized cost or fair value of the collateral less cost to sell.