Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2012	Oct. 31, 2011
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 486,933	$ 287,735
Bank loans and other investments	430,583	462,586
Senior and subordinated note obligations	446,605	477,699
Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	31,148	39,841
Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	350	278
Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	257,652	46,900
Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,530	7,507
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	16,390	6,691
Total financial assets	170,288	172,831
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	34,561	15,829
Bank loans and other investments	98	85
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	87,991	102,790
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	4,512	11,308
Level 1 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	26,736	36,128
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	139,469	360,676
Derivative instruments	2,229	1,060
Total financial assets	672,202	901,188
Level 2 [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	788	6,654
Securities sold, not yet purchased	26,142	6,270
Total financial liabilities	29,589	12,924
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
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	428,282	456,591
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	31,457	5,197
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	66,293	73,914
Level 2 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4,412	3,713
Level 2 [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	60	37
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	2,203	5,910
Level 3 [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial liabilities	443,946	477,699
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	443,946	477,699
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	2,203	5,910
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	265,472	54,648
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	350	278
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	257,652	46,900
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	155,859	367,367
Derivative instruments	2,229	1,060
Total financial assets	1,110,165	1,134,577
Total Fair Value [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	788	6,654
Securities sold, not yet purchased	26,142	6,270
Total financial liabilities	473,535	490,623
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	446,605	477,699
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	34,561	15,829
Bank loans and other investments	430,583	462,586
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	119,448	107,987
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	70,805	85,222
Total Fair Value [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	31,148	39,841
Total Fair Value [Member] | Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	350	278
Total Fair Value [Member] | Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	257,652	46,900
Total Fair Value [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 7,530	$ 7,507