Restrictions on Cash and Due from Banks and Certain Securities - Additional Information (Detail) (USD $) In Millions	Jun. 30, 2011	Dec. 31, 2010	Jun. 30, 2010
Restricted Cash and Cash Equivalents Items [Line Items]
Required average reserve balances with the Federal Reserve Bank of New York or other banks	$ 833	$ 835	$ 788
Bank Time Deposits
Restricted Cash and Cash Equivalents Items [Line Items]
Time deposits maintained separately for two international banking entities as required by the Puerto Rico International Banking Center Law	0.6	0.6	0.6
Collateral for Letter of Credit
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	2	5	6
Guaranteeing Title and Insured Properties
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	1	1	2
Credit Card Network
Restricted Cash and Cash Equivalents Items [Line Items]
Restricted cash	$ 14	$ 12	$ 12