Loans - Summary of TDR and Related Credit Loss Reserves for TDR Loans (Detail) (USD $) In Millions, unless otherwise specified	Jun. 30, 2014		Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
TDR Loans	$ 1,200	[1],[2],[3]	$ 1,370	[1],[2],[3]
Allowance for credit losses on TDR Loans	67	[4]	87	[4]
Unpaid Principal Balance of TDR Loans	1,440		1,609
Commercial Loan [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	233	[1],[3]	389	[1],[3]
Allowance for credit losses on TDR Loans	7	[4]	17	[4]
Unpaid Principal Balance of TDR Loans	287		448
Commercial Loan [Member] | Construction and Other Real Estate [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	205	[1],[3]	292	[1],[3]
Allowance for credit losses on TDR Loans	2	[4]	16	[4]
Unpaid Principal Balance of TDR Loans	219		309
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	28	[1],[3]	21	[1],[3]
Allowance for credit losses on TDR Loans	5	[4]	1	[4]
Unpaid Principal Balance of TDR Loans	68		60
Commercial Loan [Member] | Global Banking [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	0	[1],[3]	51	[1],[3]
Unpaid Principal Balance of TDR Loans	0		51
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	0	[1],[3]	25	[1],[3]
Unpaid Principal Balance of TDR Loans	0		28
Consumer Loans [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	967	[1],[3]	981	[1],[3]
Allowance for credit losses on TDR Loans	60	[4]	70	[4]
Unpaid Principal Balance of TDR Loans	1,153		1,161
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	959	[1],[3],[5]	973	[1],[3],[5]
Allowance for credit losses on TDR Loans	58	[4]	68	[4]
Unpaid Principal Balance of TDR Loans	1,145		1,153
Consumer Loans [Member] | Credit Cards [Member]
Financing Receivable, Impaired [Line Items]
TDR Loans	8	[1],[3]	8	[1],[3]
Allowance for credit losses on TDR Loans	2	[4]	2	[4]
Unpaid Principal Balance of TDR Loans	$ 8		$ 8

[1] 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 $33 million and $92 million at June 30, 2014 and December 31, 2013, respectively.

[2] Includes $343 million and $458 million at June 30, 2014 and December 31, 2013, respectively, of loans which are classified as nonaccrual.

[3] 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:June 30, 2014 December 31, 2013 (in millions)Commercial loans: Construction and other real estate$219 $309Business and corporate banking68 60Global banking— 51Other commercial— 28Total commercial287 448Consumer loans: Residential mortgages1,145 1,153Credit cards8 8Total consumer1,153 1,161Total$1,440 $1,609

[4] Included in the allowance for credit losses.

[5] Includes $725 million and $706 million at June 30, 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.