Loans - Summary of Nonaccrual Loans and Accruing Receivables 90 Days or More Delinquent (Detail) (USD $)	Mar. 31, 2014		Dec. 31, 2013
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	$ 1,175,000,000		$ 1,305,000,000
Total accruing loans contractually past due 90 days or more	34,000,000		34,000,000
Total nonperforming loans	1,209,000,000		1,339,000,000
Commercial Loan [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	118,000,000		254,000,000
Total accruing loans contractually past due 90 days or more	7,000,000		6,000,000
Commercial Loan [Member] | Construction and land loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	32,000,000		44,000,000
Commercial Loan [Member] | Other real estate [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	62,000,000		122,000,000
Commercial Loan [Member] | Business and Corporate Banking [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	21,000,000		21,000,000
Total accruing loans contractually past due 90 days or more	6,000,000		5,000,000
Commercial Loan [Member] | Global Banking [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	0		65,000,000
Total accruing loans contractually past due 90 days or more	0		0
Commercial Loan [Member] | Other Commercial [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	3,000,000		2,000,000
Total accruing loans contractually past due 90 days or more	1,000,000		1,000,000
Consumer Loans [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	978,000,000		1,026,000,000
Total accruing loans contractually past due 90 days or more	27,000,000		28,000,000
Consumer Loans [Member] | Residential Mortgage [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	907,000,000		949,000,000
Total accruing loans contractually past due 90 days or more	0		0
Consumer Loans [Member] | Home Equity Mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	71,000,000		77,000,000
Total accruing loans contractually past due 90 days or more	0		0
Consumer Loans [Member] | Total residential mortgages [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	978,000,000	[1],[2],[3]	1,026,000,000	[1],[2],[3]
Total accruing loans contractually past due 90 days or more	0		0
Consumer Loans [Member] | Credit Card Receivable [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total accruing loans contractually past due 90 days or more	14,000,000		14,000,000
Consumer Loans [Member] | Other consumer
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	0		0
Total accruing loans contractually past due 90 days or more	13,000,000		14,000,000
Nonaccrual Loans Held For Sale [Member]
Financing Receivable, Recorded Investment, Past Due [Line Items]
Total nonaccruing loans	$ 79,000,000		$ 25,000,000

[1] At March 31, 2014 and December 31, 2013, residential mortgage loan nonaccrual balances include $853 million and $866 million, respectively, of loans that are carried at the lower of amortized cost or fair value of the collateral less cost to sell.

[2] Residential mortgage nonaccrual loans for all periods does not include guaranteed loans purchased from the Government National Mortgage Association ("GNMA"). Repayment of these loans are predominantly insured by the Federal Housing Administration and as such, these loans have different risk characteristics from the rest of our customer loan portfolio.

[3] Nonaccrual residential mortgages includes all receivables which are 90 or more days contractually delinquent as well as loans discharged under Chapter 7 bankruptcy and not re-affirmed and second lien loans where the first lien loan that we own or service is 90 or more days contractually delinquent.