Fair Value Measurements (Details) (USD $) In Thousands, unless otherwise specified	Jul. 31, 2013	Oct. 31, 2012
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 545,474	$ 486,933
Bank loans and other investments	245,991	430,583
Senior and subordinated note obligations	291,175	446,605
Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	17,457	31,148
Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	317	350
Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	271,044	257,652
Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	7,531	7,530
Level 1 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	99,310	16,390
Total financial assets	294,872	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	56,725	34,561
Bank loans and other investments		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	52,137	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	74,601	4,512
Level 1 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	12,099	26,736
Level 2 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Cash equivalents	3,700	139,469
Derivative instruments	1,302	2,229
Total financial assets	375,754	672,202
Level 2 [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Derivative instruments	6,668	788
Securities sold, not yet purchased	1,572	26,142
Total financial liabilities	10,875	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	2,635	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	242,946	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	38,085	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	73,825	66,293
Level 2 [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Cash Management Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10,477
Level 2 [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5,358	4,412
Level 2 [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	61	60
Level 3 [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial assets	3,045	2,203
Level 3 [Member] | Financial Liabilities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Total financial liabilities	288,540	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	288,540	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	3,045	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	278,831	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	317	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	271,044	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	103,010	155,859
Derivative instruments	1,302	2,229
Total financial assets	952,502	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	6,668	788
Securities sold, not yet purchased	1,572	26,142
Total financial liabilities	299,415	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	291,175	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	56,725	34,561
Bank loans and other investments	245,991	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	90,222	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	148,426	70,805
Total Fair Value [Member] | Categories of Investments, Marketable Securities, Trading Securities [Member] | Cash Management Assets [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	10,477
Total Fair Value [Member] | Available-for-sale Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	17,457	31,148
Total Fair Value [Member] | Collateralized Loan Obligations [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	317	350
Total Fair Value [Member] | Equity Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	271,044	257,652
Total Fair Value [Member] | Cost Method Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 7,531	$ 7,530