Summary of Significant Accounting Policies	3 Months Ended
Jan. 31, 2018
Summary of Significant Accounting Policies Disclosure [Abstract]
Summary of Significant Accounting Policies	1. Summary of Significant Accounting Policies Basis of presentation In the opinion of management, the accompanying unaudited interim Consolidated Financial Statements of Eaton Vance Corp. (the Company) include all adjustments necessary to present fairly the results for the interim periods in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP). Such financial statements have been prepared in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures have been omitted pursuant to such rules and regulations. As a result, these financial statements should be read in conjunction with the audited Consolidated Financial Statements and related notes included in the Company's latest Annual Report on Form 10-K. Adoption of new accounting standard In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update, Improvements to Employee Share-Based Payment Accounting (ASU 2016-09), which simplifies certain aspects of the accounting for share-based payment transactions. The Company adopted ASU 2016-09 as of November 1, 2017. One of the impacts of adoption is that excess tax benefits or tax deficiencies related to the exercise of stock options and vesting of restricted stock awards are no longer recognized in additional paid-in capital but rather as an income tax benefit or income tax expense in the period of vesting or settlement. This provision requires a prospective approach to adoption. The Company recognized an excess tax benefit of $11.9 million for the three months ended January 31, 2018 attributable to the exercise of stock options and vesting of restricted stock awards in conjunction with the adoption of this ASU. This guidance also requires that the excess tax benefits or tax deficiencies described above be classified as an operating cash flow within the Consolidated Statements of Cash Flows as opposed to a financing cash flow, as previously reported. The Company elected to use a retrospective approach to the adoption of this provision. As a result, the excess tax benefit of $5.7 million recognized for the three months ended January 31, 2017 was reclassified out of financing activities and into operating activities. Finally, the guidance allows companies to elect to continue to account for forfeitures using an estimate or instead to elect to account for forfeitures as they occur. Upon adoption, the Company elected to account for forfeitures as they occur and adopted this provision using the modified retrospective approach. Therefore, upon adoption, the Company recognized a $0.5 million cumulative effect adjustment (reduction) to retained earnings, net of related income tax effects, to reflect the timing difference of when forfeitures are recognized in the measurement of stock-based compensation cost. The Company's accounting policy related to stock-based compensation has been amended to reflect the adoption of this new accounting standard and is summarized below. Stock-based compensation The Company accounts for stock‐based compensation expense at fair value. Under the fair value method, stock‐based compensation expense, which reflects the fair value of stock‐based awards measured at grant date, is recognized on a straight‐line basis over the relevant service period (generally five years) and is adjusted each period for forfeitures as they occur. The fair value of each option award granted is estimated using the Black‐Scholes option valuation model. The Black‐Scholes option valuation model incorporates assumptions as to dividend yield, expected volatility, an appropriate risk‐free interest rate and the expected life of the option. The fair value of profit interests granted under subsidiary long‐term equity plans is estimated on the grant date by averaging fair value established using an income approach and fair value established using a market approach for each subsidiary. The tax effect of the difference, if any, between the cumulative compensation expense recognized for a stock-based award for financial reporting purposes and the deduction for such award for tax purposes is recognized as income tax expense (for tax deficiencies) or benefit (for excess tax benefits) in the Company's Consolidated Statements of Income in the period in which the tax deduction arises (generally in the period of vesting or settlement of a stock-based award, as applicable) and are reflected as an operating activity on the Company's Consolidated Statements of Cash Flows. Shares of non-voting common stock withheld for tax withholding purposes upon the vesting of restricted share awards are reflected as a financing activity in the Company's Consolidated Statements of Cash Flows.

Summary of Significant Accounting Policies

3 Months Ended

Jan. 31, 2018

Summary of Significant Accounting Policies Disclosure [Abstract]

Summary of Significant Accounting Policies

1. Summary of Significant Accounting Policies

Basis of presentation

In the opinion of management, the accompanying unaudited interim Consolidated Financial Statements of Eaton Vance Corp. (the Company) include all adjustments necessary to present fairly the results for the interim periods in accordance with accounting principles generally accepted in the United States of America (U.S. GAAP). Such financial statements have been prepared in accordance with the instructions to Form 10-Q pursuant to the rules and regulations of the Securities and Exchange Commission. Certain information and footnote disclosures have been omitted pursuant to such rules and regulations. As a result, these financial statements should be read in conjunction with the audited Consolidated Financial Statements and related notes included in the Company's latest Annual Report on Form 10-K.

Adoption of new accounting standard

In March 2016, the Financial Accounting Standards Board (FASB) issued Accounting Standard Update, Improvements to Employee Share-Based Payment Accounting (ASU 2016-09), which simplifies certain aspects of the accounting for share-based payment transactions. The Company adopted ASU 2016-09 as of November 1, 2017. One of the impacts of adoption is that excess tax benefits or tax deficiencies related to the exercise of stock options and vesting of restricted stock awards are no longer recognized in additional paid-in capital but rather as an income tax benefit or income tax expense in the period of vesting or settlement. This provision requires a prospective approach to adoption. The Company recognized an excess tax benefit of $11.9 million for the three months ended January 31, 2018 attributable to the exercise of stock options and vesting of restricted stock awards in conjunction with the adoption of this ASU.

This guidance also requires that the excess tax benefits or tax deficiencies described above be classified as an operating cash flow within the Consolidated Statements of Cash Flows as opposed to a financing cash flow, as previously reported. The Company elected to use a retrospective approach to the adoption of this provision. As a result, the excess tax benefit of $5.7 million recognized for the three months ended January 31, 2017 was reclassified out of financing activities and into operating activities.

Finally, the guidance allows companies to elect to continue to account for forfeitures using an estimate or instead to elect to account for forfeitures as they occur. Upon adoption, the Company elected to account for forfeitures as they occur and adopted this provision using the modified retrospective approach. Therefore, upon adoption, the Company recognized a $0.5 million cumulative effect adjustment (reduction) to retained earnings, net of related income tax effects, to reflect the timing difference of when forfeitures are recognized in the measurement of stock-based compensation cost.

The Company's accounting policy related to stock-based compensation has been amended to reflect the adoption of this new accounting standard and is summarized below.

Stock-based compensation

The Company accounts for stock‐based compensation expense at fair value. Under the fair value method, stock‐based compensation expense, which reflects the fair value of stock‐based awards measured at grant date, is recognized on a straight‐line basis over the relevant service period (generally five years) and is adjusted each period for forfeitures as they occur.

The fair value of each option award granted is estimated using the Black‐Scholes option valuation model. The Black‐Scholes option valuation model incorporates assumptions as to dividend yield, expected volatility, an appropriate risk‐free interest rate and the expected life of the option.

The fair value of profit interests granted under subsidiary long‐term equity plans is estimated on the grant date by averaging fair value established using an income approach and fair value established using a market approach for each subsidiary.

The tax effect of the difference, if any, between the cumulative compensation expense recognized for a stock-based award for financial reporting purposes and the deduction for such award for tax purposes is recognized as income tax expense (for tax deficiencies) or benefit (for excess tax benefits) in the Company's Consolidated Statements of Income in the period in which the tax deduction arises (generally in the period of vesting or settlement of a stock-based award, as applicable) and are reflected as an operating activity on the Company's Consolidated Statements of Cash Flows. Shares of non-voting common stock withheld for tax withholding purposes upon the vesting of restricted share awards are reflected as a financing activity in the Company's Consolidated Statements of Cash Flows.