v2.4.0.6
Commitments And Contingencies (Narrative) (Detail) (USD $)
In Millions, unless otherwise specified
6 Months Ended
Jun. 30, 2012
Long-term Purchase Commitment [Line Items]  
Estimated term for resolution for legal matters related to indemnification 3 years
Fair value of the indemnification obligation $ 385
Fair value of the indemnification obligation 256
Estimated aggregate amount of losses reasonably to be incurred in excess of amounts 200
Carrying Amount [Member]
 
Long-term Purchase Commitment [Line Items]  
Indemnification obligation 383
Fair Value Inputs Total [Member]
 
Long-term Purchase Commitment [Line Items]  
Indemnification obligation 383
Morgan Keegan [Member]
 
Long-term Purchase Commitment [Line Items]  
Fair value of the indemnification obligation $ 256