Investments In Affiliates (Details) (USD $)	6 Months Ended
Apr. 30, 2012 Lloyd George Management Limited [Member]	Apr. 30, 2011 Lloyd George Management Limited [Member]	Apr. 30, 2012 Private Equity Partnership [Member]	Oct. 31, 2011 Private Equity Partnership [Member]	Apr. 30, 2012 Eaton Vance Diversified Currency Income Fund [Member]	Oct. 31, 2011 Eaton Vance Parametric Structured Commodity Strategy Fund [Member]	Oct. 31, 2011 Eaton Vance Parametric Option Absolute Return Strategy Fund[ Member]
Schedule Of Equity Method Investments [Line Items]
Equity method investment ownership percentage			7.00%	7.00%	32.00%	47.00%	27.00%
Equity method investment aggregate cost			$ 9,700,000	$ 18,400,000	$ 16,535,000	$ 9,190,000	$ 19,298,000
Realized gains	$ 2,400,000	$ 5,500,000

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 159

-Paragraph 18

-Subparagraph f

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Accounting Principles Board Opinion (APB)

-Number 18

-Paragraph 20

-Subparagraph a (1)

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 323

-SubTopic 10

-Section 50

-Paragraph 3

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6382943&loc=d3e33918-111571

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