Investments (Details) (USD $)
In Thousands, unless otherwise specified
Oct. 31, 2011
Oct. 31, 2010
Schedule Of Investments [Line Items]    
Investments $ 287,735 $ 334,409
Corporate Debt Securities [Member]
   
Schedule Of Investments [Line Items]    
Investments 4,832 4,732
Consolidated Funds [Member] | Equity Securities [Member]
   
Schedule Of Investments [Line Items]    
Investments 74,434 88,184
Consolidated Funds [Member] | Debt Securities [Member]
   
Schedule Of Investments [Line Items]    
Investments 69,083 111,585
Separately Managed Accounts [Member] | Equity Securities [Member]
   
Schedule Of Investments [Line Items]    
Investments 33,553 28,692
Separately Managed Accounts [Member] | Debt Securities [Member]
   
Schedule Of Investments [Line Items]    
Investments 11,307 3,666
Available-for-sale Securities [Member]
   
Schedule Of Investments [Line Items]    
Investments 39,841 37,541
Collateralized Loan Obligations [Member]
   
Schedule Of Investments [Line Items]    
Investments 278 1,391
Equity Method Investments [Member]
   
Schedule Of Investments [Line Items]    
Investments 46,900 51,111
Cost Method Investments [Member]
   
Schedule Of Investments [Line Items]    
Investments $ 7,507 $ 7,507