Guarantees and Contingent Liabilities - Additional Information (Detail) (USD $)	9 Months Ended
	Sep. 30, 2012	Jun. 30, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Dec. 31, 2010
Liability related to remaining Visa Litigation, carrying amount	$ 65,000,000
Value of airline tickets purchased to deliver at a future date	5,900,000,000
Company held collateral in escrow deposits, letters of credit and indemnities from financial institutions, and liens on various assets	610,000,000
Representation and warranty reserve	220,000,000	216,000,000	160,000,000	162,000,000	173,000,000	180,000,000
Increase in representation and warranty reserve primarily due to an increase in the number of loans selected for repurchase review	60,000,000
Unresolved representation and warranty claims	118,000,000		105,000,000
Settlement amount by the Company in exchange for a release of claims	55,000,000
Accrual of potential settlement related to mortgage activities	$ 130,000,000