Fair Value Measurements of Other Financial Instruments (Details) (USD $)	Apr. 30, 2012	Oct. 31, 2011
Fair Value Measurements of Other Financial Instruments (Details)
Carrying value of other investments	$ 7,470,000	$ 7,470,000
Fair value of other investments		7,470,000
Carrying value of notes receivable from stock option exercises	4,171,000	4,441,000
Fair value of notes receivable from stock option exercises		4,441,000
Carrying value of debt	500,000,000	500,000,000
Fair value of debt		566,047,000
Carrying value of non-controlling capital interest in ACM Holdings	6,600,000
Level 1 [Member]
Fair Value Measurements of Other Financial Instruments (Details)
Fair value of debt	571,628,000
Level 3 [Member]
Fair Value Measurements of Other Financial Instruments (Details)
Fair value of other investments	7,470,000
Fair value of notes receivable from stock option exercises	4,171,000
Fair value of non-controlling capital interest in ACM Holdings	$ 6,600,000

Name:	ev_CarryingAndFairValueLineItems
Namespace Prefix:	ev_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Carrying amount of the capital interests owned by noncontrolling partners of a limited liability company included in the entity's consolidated financial statements.

+ References

No definition available.

+ Details

Name:	ev_MinorityInterestInLimitedLiabilityCompany
Namespace Prefix:	ev_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Fair value of the capital interests owned by noncontrolling partners of a limited liability company included in the entity's consolidated financial statements.

+ References

No definition available.

+ Details

Name:	ev_MinorityInterestInLimitedLiabilityCompanyFairValue
Namespace Prefix:	ev_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

The fair value of other investments held by the Company.

+ References

No definition available.

+ Details

Name:	ev_OtherInvestmentsFairValue
Namespace Prefix:	ev_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amounts receivable from officers and directors resulting from the sale of stock to officers or directors before the cash payment is received at fair value.

+ References

No definition available.

+ Details

Name:	ev_ReceivableFromOfficersAndDirectorsForIssuanceOfCapitalStockFairValue
Namespace Prefix:	ev_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Including current and noncurrent portions, aggregate carrying amount of long-term borrowings as of the balance sheet date. May include notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt, which had initial maturities beyond one year or beyond the normal operating cycle, if longer, and after deducting unamortized discount or premiums, if any.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.22)

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.16)

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Article 7

-Section 03

-Paragraph 16

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.16)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 16

-Article 9

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 20, 22

-Article 5

+ Details

Name:	us-gaap_LongTermDebt
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

+ References

No definition available.

+ Details

Name:	us-gaap_LongTermDebtFairValue
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Includes other investments and securities that are not at fair value as of the balance sheet date and those that are not accounted for under the equity method.

+ References

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph a

-Subparagraph 1(g)

-Article 7

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 944

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.7-03.1)

-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

+ Details

Name:	us-gaap_OtherInvestmentsAndSecuritiesAtCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Amounts receivable from officers and directors resulting from the sale of stock to officers or directors before the cash payment is received.

+ References

+ Details

Name:	us-gaap_ReceivableFromOfficersAndDirectorsForIssuanceOfCapitalStock
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant