v2.4.0.6
Fair Value of Assets and Liabilities - Additional Information (Detail) (Securities Financing Transaction, Fair Value, USD $)
In Millions, unless otherwise specified
Mar. 31, 2013
Dec. 31, 2012
Securities Financing Transaction, Fair Value
   
Fair Value, Off-balance Sheet Risks, Disclosure Information [Line Items]    
Fair value of client securities pledged in securities lending transactions to other broker-dealers $ 1,100 $ 852
Fair value of borrowed securities from other broker-dealers to fulfill short sales by clients $ 279 $ 121