Guarantees and Contingent Liabilities - Additional Information (Detail) (USD $)	Mar. 31, 2013	Dec. 31, 2012	Mar. 31, 2012	Dec. 31, 2011
Guarantees And Contingent Liabilities Textual [Abstract]
Liability related to remaining Visa Litigation, carrying amount	$ 65,000,000
Value of airline tickets purchased to deliver at a future date	7,100,000,000
Company held collateral in escrow deposits, letters of credit and indemnities from financial institutions, and liens on various assets	608,000,000
Representation and warranty reserve	233,000,000	240,000,000	202,000,000	160,000,000
Unresolved representation and warranty claims	66,000,000	131,000,000
Accrual of potential settlement related to mortgage activities	$ 130,000,000