Investments (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Oct. 31, 2016
Schedule Of Investments [Line Items]
Investments	$ 705,197	$ 589,773
Total investment securities, trading	528,538	413,541
Equity Securities [Member]
Schedule Of Investments [Line Items]
Total investment securities, trading	205,669	136,031
Debt Securities [Member]
Schedule Of Investments [Line Items]
Total investment securities, trading	253,954	191,688
Trading Account Assets [Member]
Schedule Of Investments [Line Items]
Total investment securities, trading	528,538	413,541
Short Term Debt Securities[Member]
Schedule Of Investments [Line Items]
Investments	68,915	85,822
Consolidated Sponsored Funds [Member]
Schedule Of Investments [Line Items]
Investments	374,128	248,036
Separately Managed Accounts [Member]
Schedule Of Investments [Line Items]
Investments	85,495	79,683
Available-for-sale Securities [Member]
Schedule Of Investments [Line Items]
Investments	10,148	13,312
Investments in non-consolidated CLO entities [Member]
Schedule Of Investments [Line Items]
Investments	3,927	3,837
Equity Method Investments [Member]
Schedule Of Investments [Line Items]
Investments	143,430	139,929
Cost Method Investments [Member]
Schedule Of Investments [Line Items]
Investments	$ 19,154	$ 19,154