Investments (Details) (USD $) In Thousands, unless otherwise specified	Apr. 30, 2014	Oct. 31, 2013
Schedule Of Investments [Line Items]
Investments	$ 648,567	$ 536,323
Total investment securities, trading	404,164	235,524
Equity Securities [Member]
Schedule Of Investments [Line Items]
Total investment securities, trading	120,681	117,758
Debt Securities [Member]
Schedule Of Investments [Line Items]
Total investment securities, trading	90,974	97,650
Trading Account Assets [Member]
Schedule Of Investments [Line Items]
Total investment securities, trading	404,164	235,524
Short Term Debt Investment [Member] | Trading Account Assets [Member]
Schedule Of Investments [Line Items]
Investments	192,509	20,116
Consolidated Sponsored Funds [Member] | Trading Account Assets [Member]
Schedule Of Investments [Line Items]
Investments	158,510	153,327
Separately Managed Accounts [Member] | Trading Account Assets [Member]
Schedule Of Investments [Line Items]
Investments	53,145	62,081
Available-for-sale Securities [Member]
Schedule Of Investments [Line Items]
Investments	18,662	22,727
Investments in non-consolidated CLO entities [Member]
Schedule Of Investments [Line Items]
Investments	7,714	5,378
Equity Method Investments [Member]
Schedule Of Investments [Line Items]
Investments	214,238	269,683
Cost Method Investments [Member]
Schedule Of Investments [Line Items]
Investments	$ 3,789	$ 3,011