Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jan. 31, 2013	Oct. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 482,329	$ 486,933
Bank loans and other investments	380,672	430,583
Senior and subordinated note obligations	411,583	446,605
Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	23,072	31,148
Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	398	350
Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	236,095	257,652
Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,530	7,530
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,248	16,390
Total financial assets	189,914	170,288
Level 1 [Member] | Assets Of Consolidated Collateralized Loan Obligation Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	47,422	34,561
Bank loans and other investments	0	98
Level 1 [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	115,127	87,991
Level 1 [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,835	4,512
Level 1 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	18,282	26,736
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	39,491	139,469
Derivative instruments	1,138	2,229
Total financial assets	517,765	672,202
Level 2 [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	8,492	788
Securities sold, not yet purchased	3,187	26,142
Total financial liabilities	14,338	29,589
Level 2 [Member] | Financial Liabilities [Member] | Liabilities Of Consolidated Collateralized Loan Obligation Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior and subordinated note obligations	2,659	2,659
Level 2 [Member] | Assets Of Consolidated Collateralized Loan Obligation Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loans and other investments	378,014	428,282
Level 2 [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	48,225	31,457
Level 2 [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	46,047	66,293
Level 2 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,790	4,412
Level 2 [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	60	60
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	2,658	2,203
Level 3 [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial liabilities	408,924	443,946
Level 3 [Member] | Financial Liabilities [Member] | Liabilities Of Consolidated Collateralized Loan Obligation Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior and subordinated note obligations	408,924	443,946
Level 3 [Member] | Assets Of Consolidated Collateralized Loan Obligation Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Bank loans and other investments	2,658	2,203
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	243,963	265,472
Other Assets Not Held At Fair Value Investments [Member] | Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	398	350
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	236,095	257,652
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	7,470	7,470
Total Fair Value [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	42,739	155,859
Derivative instruments	1,138	2,229
Total financial assets	954,300	1,110,165
Total Fair Value [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	8,492	788
Securities sold, not yet purchased	3,187	26,142
Total financial liabilities	423,262	473,535
Total Fair Value [Member] | Financial Liabilities [Member] | Liabilities Of Consolidated Collateralized Loan Obligation Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior and subordinated note obligations	411,583	446,605
Total Fair Value [Member] | Assets Of Consolidated Collateralized Loan Obligation Entity [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	47,422	34,561
Bank loans and other investments	380,672	430,583
Total Fair Value [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	163,352	119,448
Total Fair Value [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	51,882	70,805
Total Fair Value [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	23,072	31,148
Total Fair Value [Member] | Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	398	350
Total Fair Value [Member] | Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	236,095	257,652
Total Fair Value [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 7,530	$ 7,530