Fair Value of Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Thousands	Jan. 31, 2017	Oct. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 705,197	$ 589,773
Consolidated Sponsored Funds [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	374,128	248,036
Separately Managed Accounts [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	85,495	79,683
Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10,148	13,312
Investments in non-consolidated CLO entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	3,927	3,837
Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	143,430	139,929
Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	19,154	19,154
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	17,923	21,875
Total financial assets	211,715	145,174
Level 1 [Member] | Trading Account Assets [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	161,567	93,491
Level 1 [Member] | Trading Account Assets [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	24,470	18,757
Level 1 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,755	11,051
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	31,086	35,913
Derivative instruments	329	2,072
Total financial assets	376,429	341,659
Level 2 [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	3,951	815
Total financial liabilities	3,951	815
Level 2 [Member] | Trading Account Assets [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	44,102	42,540
Level 2 [Member] | Trading Account Assets [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	229,484	172,931
Level 2 [Member] | Trading Account Assets [Member] | Short Term Debt Securities[Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	68,915	85,822
Level 2 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	2,393	2,261
Level 2 [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	120	120
Other Assets Not Held At Fair Value Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	166,391	162,800
Other Assets Not Held At Fair Value Investments [Member] | Investments in non-consolidated CLO entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	3,927	3,837
Other Assets Not Held At Fair Value Investments [Member] | Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	143,430	139,929
Other Assets Not Held At Fair Value Investments [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	19,034	19,034
Total Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	49,009	57,788
Derivative instruments	329	2,072
Total financial assets	754,535	649,633
Total Fair Value [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	3,951	815
Total financial liabilities	3,951	815
Total Fair Value [Member] | Trading Account Assets [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	205,669	136,031
Total Fair Value [Member] | Trading Account Assets [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	253,954	191,688
Total Fair Value [Member] | Trading Account Assets [Member] | Short Term Debt Securities[Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	68,915	85,822
Total Fair Value [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10,148	13,312
Total Fair Value [Member] | Investments in non-consolidated CLO entities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	3,927	3,837
Total Fair Value [Member] | Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	143,430	139,929
Total Fair Value [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 19,154	$ 19,154