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Label Element Value
Risk/Return: rr_RiskReturnAbstract  
Central Index Key dei_EntityCentralIndexKey 0000102816
Eaton Vance Worldwide Health Sciences Fund  
Risk/Return: rr_RiskReturnAbstract  
Investment Objective, Heading rr_ObjectiveHeading Investment Objective
Investment Objective, Primary rr_ObjectivePrimaryTextBlock

The Fund's investment objective is to seek long-term capital growth by investing in a worldwide and diversified portfolio of health sciences companies.
Expense, Heading rr_ExpenseHeading Fees and Expenses of the Fund
Expense, Narrative rr_ExpenseNarrativeTextBlock

This table describes the fees and expenses that you may pay if you buy and hold shares of the Fund. Investors may also pay commissions or other fees to their financial intermediary when they buy and hold shares of the Fund, which are not reflected below. You may qualify for a reduced sales charge on purchases of Class A shares if you invest, or agree to invest over a 13-month period, at least $50,000 in Eaton Vance funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix A – Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial intermediary and in Sales Charges beginning on page 19 of this Prospectus and page 22 of the Fund’s Statement of Additional Information.
Shareholder Fees, Caption rr_ShareholderFeesCaption Shareholder Fees (fees paid directly from your investment)
Operating Expenses, Caption rr_OperatingExpensesCaption Annual Fund Operating Expenses (expenses you pay each year as a percentage of the value of your investment)
Portfolio Turnover, Heading rr_PortfolioTurnoverHeading Portfolio Turnover
Portfolio Turnover rr_PortfolioTurnoverTextBlock

The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” the portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when Fund shares are held in a taxable account. These costs, which are not reflected in Annual Fund Operating Expenses or in the Example, affect the Fund’s performance. Through August 9, 2019, the Fund invested its assets in Worldwide Health Sciences Portfolio (the “Portfolio”), a separate registered investment company with the same objective and policies as the Fund. For the period from September 1, 2018 through August 9, 2019, the Portfolio's portfolio turnover rate was 32% of the average value of its portfolio. For the period from August 12, 2019 through August 31, 2019, the Fund's portfolio turnover rate was 3% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 32.00%
Expense Breakpoint, Discounts rr_ExpenseBreakpointDiscounts You may qualify for a reduced sales charge on purchases of Class A shares if you invest, or agree to invest over a 13-month period, at least $50,000 in Eaton Vance funds. Certain financial intermediaries also may offer variations in Fund sales charges to their customers as described in Appendix A – Financial Intermediary Sales Charge Variations in this Prospectus. More information about these and other discounts is available from your financial intermediary and in Sales Charges beginning on page 19 of this Prospectus and page 22 of the Fund’s Statement of Additional Information.
Expense Breakpoint, Minimum Investment Required [Amount] rr_ExpenseBreakpointMinimumInvestmentRequiredAmount $ 50,000
Expense Example, Heading rr_ExpenseExampleHeading Example.
Expense Example, Narrative rr_ExpenseExampleNarrativeTextBlock

This Example is intended to help you compare the cost of investing in the Fund with the cost of investing in other mutual funds. The Example assumes that you invest $10,000 in the Fund for the time periods indicated and then redeem all of your shares at the end of those periods. The Example also assumes that your investment has a 5% return each year, that the operating expenses remain the same and that any expense reimbursement arrangement remains in place for the contractual period. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Investment Strategy, Heading rr_StrategyHeading Principal Investment Strategies
Investment Strategy, Narrative rr_StrategyNarrativeTextBlock

The Fund normally invests at least 80% of its net assets (plus any borrowings for investment purposes) in securities (primarily common stocks) of companies principally engaged in the discovery, development, production or distribution of products (or services) related to scientific advances in health care, including biotechnology, pharmaceuticals, diagnostics, managed health care and medical equipment and supplies (“health sciences companies”) (the “80% Policy”). A company will be considered to be a health sciences company if, at the time of investment, 50% or more of the company’s sales, earnings or assets will arise from or will be dedicated to the application of scientific advances related to health care. The Fund invests in U.S. and foreign securities and will normally be invested in issuers located in and tied economically to at least three different countries. The Fund may invest in securities of both larger established and smaller emerging companies domiciled in developed or emerging markets, some of which may be denominated in foreign currencies or trade in the form of depositary receipts. The Fund has a policy of investing at least 25% of its assets in investments in the medical research and health care industry. Companies in the medical research and health care industry are categorized by the Global Industry Classification Standard as pharmaceuticals, biotechnology, life sciences and health care equipment and services companies. The Fund may invest up to 5% of its total assets in royalty bonds, which are debt securities that are collateralized by royalties from pharmaceutical patents. The Fund may also invest in exchange-traded funds (“ETFs”), a type of pooled investment vehicle, in order to manage cash positions or seek exposure to certain markets or market sectors and may lend its securities.

The Fund may engage in derivative transactions to seek return, to hedge against fluctuations in securities prices or currency exchange rates, or as a substitute for the purchase or sale of securities or currencies. The Fund expects to use derivatives primarily to seek to generate income by writing covered call options or put options. The Fund may also enter into a combination of option transactions on individual securities. In addition, the Fund may seek to hedge against fluctuations in currency exchange rates through the use of forward foreign currency exchange contracts. Permitted derivatives include: the purchase or sale of forward or futures contracts; options on futures contracts; exchange-traded and over-the-counter options; equity collars and equity swap agreements. The Fund may also engage in covered short sales (on individual securities held or on an index or basket of securities whose constituents are held in whole or in part or for which liquid assets have been segregated). There is no stated limit on the Fund’s use of derivatives.

Investment decisions are made primarily on the basis of fundamental research. The portfolio managers utilize information provided by, and the expertise of, the investment adviser’s and sub-adviser’s research staff in making investment decisions. In selecting stocks, the portfolio managers consider (among other factors) a company’s earnings or cash flow capabilities, dividend prospects, financial strength, growth potential, the strength of the company’s business franchises and management team, sustainability of a company’s competitiveness, and estimates of the company’s net value. The portfolio managers may sell a security when the investment adviser’s or sub-adviser’s price objective for the security is reached, the fundamentals of the company deteriorate, a security’s price falls below acquisition cost or to pursue more attractive investment options. The portfolio managers seek to manage investment risk by maintaining issuer diversification among the Fund’s holdings, and by conducting an analysis of the risk and return characteristics of securities (as described above) in which the Fund invests. The portfolio manager(s) may also consider financially material environmental, social and governance factors in evaluating an issuer. These considerations may be taken into account alongside other fundamental research in the securities selection process.
Strategy Portfolio Concentration rr_StrategyPortfolioConcentration The Fund normally invests at least 80% of its net assets (plus any borrowings for investment purposes) in securities (primarily common stocks) of companies principally engaged in the discovery, development, production or distribution of products (or services) related to scientific advances in health care, including biotechnology, pharmaceuticals, diagnostics, managed health care and medical equipment and supplies (“health sciences companies”) (the “80% Policy”). A company will be considered to be a health sciences company if, at the time of investment, 50% or more of the company’s sales, earnings or assets will arise from or will be dedicated to the application of scientific advances related to health care. The Fund invests in U.S. and foreign securities and will normally be invested in issuers located in and tied economically to at least three different countries. The Fund may invest in securities of both larger established and smaller emerging companies domiciled in developed or emerging markets, some of which may be denominated in foreign currencies or trade in the form of depositary receipts. The Fund has a policy of investing at least 25% of its assets in investments in the medical research and health care industry. Companies in the medical research and health care industry are categorized by the Global Industry Classification Standard as pharmaceuticals, biotechnology, life sciences and health care equipment and services companies. The Fund may invest up to 5% of its total assets in royalty bonds, which are debt securities that are collateralized by royalties from pharmaceutical patents. The Fund may also invest in exchange-traded funds (“ETFs”), a type of pooled investment vehicle, in order to manage cash positions or seek exposure to certain markets or market sectors and may lend its securities.
Risk, Heading rr_RiskHeading Principal Risks
Risk, Narrative rr_RiskNarrativeTextBlock

Market Risk. The value of investments held by the Fund may increase or decrease in response to economic, political and financial events (whether real, expected or perceived) in the U.S. and global markets. The frequency and magnitude of such changes in value cannot be predicted. Certain securities and other investments held by the Fund may experience increased volatility, illiquidity, or other potentially adverse effects in reaction to changing market conditions. Actions taken by the U.S. Federal Reserve or foreign central banks to stimulate or stabilize economic growth, such as decreases or increases in short-term interest rates, could cause high volatility in markets.

Equity Securities Risk. The value of equity securities and related instruments may decline in response to adverse changes in the economy or the economic outlook; deterioration in investor sentiment; interest rate, currency, and commodity price fluctuations; adverse geopolitical, social or environmental developments; issuer and sector-specific considerations; or other factors. Market conditions may affect certain types of stocks to a greater extent than other types of stocks. If the stock market declines in value, the value of the Fund’s equity securities will also likely decline. Although prices can rebound, there is no assurance that values will return to previous levels.

Health Sciences Concentration Risk. Because the Fund invests a significant portion of its assets in pharmaceutical, biotechnology, life sciences, and health care equipment and services companies, the value of Fund shares may be affected by developments that adversely affect such companies and may fluctuate more than that of a fund that invests more broadly. These developments include product obsolescence, the failure of a company to develop new products and the expiration of patent rights. The value of Fund shares can also be impacted by regulatory activities that affect health sciences companies. For instance, increased regulation can increase the cost of bringing new products to market and thereby reduce profits. The Fund has historically held approximately 60 stocks or less at any one time; therefore, the Fund is more sensitive to developments affecting particular stocks than would be a fund that invests more broadly.

Foreign Investment Risk. Foreign investments can be adversely affected by political, economic and market developments abroad, including the imposition of economic and other sanctions by the United States or another country. Foreign markets may be smaller, less liquid and more volatile than the major markets in the United States, and as a result, Fund share values may be more volatile. Trading in foreign markets typically involves higher expense than trading in the United States. The Fund may have difficulties enforcing its legal or contractual rights in a foreign country. Depositary receipts are subject to many of the risks associated with investing directly in foreign instruments.

Emerging Markets Investment Risk. Investment markets in emerging market countries are typically smaller, less liquid and more volatile than developed markets, and emerging market securities often involve greater risks than developed market securities.

Currency Risk. Exchange rates for currencies fluctuate daily. The value of foreign investments may be affected favorably or unfavorably by changes in currency exchange rates in relation to the U.S. dollar. Currency markets generally are not as regulated as securities markets and currency transactions are subject to settlement, custodial and other operational risks.

Smaller Company Risk. The stocks of smaller, less seasoned companies are generally subject to greater price fluctuations, limited liquidity, higher transaction costs and higher investment risk than the stocks of larger, more established companies. Such companies may have limited product lines, markets or financial resources, may be dependent on a limited management group, and may lack substantial capital reserves or an established performance record. There may be generally less publicly available information about such companies than for larger, more established companies. Stocks of these companies frequently have lower trading volumes making them more volatile and potentially more difficult to value.

Derivatives Risk. The Fund’s exposure to derivatives involves risks different from, or possibly greater than, the risks associated with investing directly in securities and other investments. The use of derivatives can lead to losses because of adverse movements in the price or value of the security, instrument, index, currency, commodity, economic indicator or event underlying a derivative (“reference instrument”), due to failure of a counterparty or due to tax or regulatory constraints. Derivatives may create leverage in the Fund, which represents a non-cash exposure to the underlying reference instrument. Leverage can increase both the risk and return potential of the Fund. Derivatives risk may be more significant when derivatives are used to enhance return or as a substitute for a cash investment position, rather than solely to hedge the risk of a position held by the Fund. Use of derivatives involves the exercise of specialized skill and judgment, and a transaction may be unsuccessful in whole or in part because of market behavior or unexpected events. Changes in the value of a derivative (including one used for hedging) may not correlate perfectly with the underlying reference instrument. Derivative instruments traded in over-the-counter markets may be difficult to value, may be illiquid, and may be subject to wide swings in valuation caused by changes in the value of the underlying reference instrument. If a derivative’s counterparty is unable to honor its commitments, the value of Fund shares may decline and the Fund could experience delays in the return of collateral or other assets held by the counterparty. The loss on derivative transactions may substantially exceed the initial investment, particularly when there is no stated limit on the Fund’s use of derivatives. A derivative investment also involves the risks relating to the reference instrument underlying the investment. 

Royalty Bonds Risk. Royalty Bonds are typically offered in a private placement pursuant to Section 4(a)(2) of the Securities Act of 1933, as amended, and are restricted as to resale. Because Royalty Bonds are restricted securities and because of the proprietary nature of the underlying pharmaceutical product licenses, it may take longer to liquidate Royalty Bond positions than would be the case for other securities. Royalty Bonds are also subject to the industry risks associated with health sciences companies.

ETF Risk. ETFs are subject to the risks of investing in the underlying securities or other investments. ETF shares may trade at a premium or discount to net asset value and are subject to secondary market trading risks. In addition, the Fund will bear a pro rata portion of the operating expenses of an ETF in which it invests. Other pooled investment vehicles generally are subject to risks similar to those of ETFs.

Securities Lending Risk. Securities lending involves a possible delay in recovery of the loaned securities or a possible loss of rights in the collateral if the borrower fails financially. The Fund could also lose money if the value of the collateral decreases.

Restricted Securities Risk. Unless registered for sale to the public under applicable federal securities law, restricted securities can be sold only in private transactions to qualified purchasers pursuant to an exemption from registration. The sale price realized from a private transaction could be less than the Fund’s purchase price for the restricted security. It may be difficult to identify a qualified purchaser for a restricted security held by the Fund and such security could be deemed illiquid. It may also be more difficult to value such securities.

Liquidity Risk. The Fund is exposed to liquidity risk when trading volume, lack of a market maker or trading partner, large position size, market conditions, or legal restrictions impair its ability to sell particular investments or to sell them at advantageous market prices. Consequently, the Fund may have to accept a lower price to sell an investment or continue to hold it or keep the position open, sell other investments to raise cash or abandon an investment opportunity, any of which could have a negative effect on the Fund’s performance. These effects may be exacerbated during times of financial or political stress.

Risks Associated with Active Management. The success of the Fund’s investment strategy depends on portfolio management’s successful application of analytical skills and investment judgment. Active management involves subjective decisions.

General Fund Investing Risks. The Fund is not a complete investment program and there is no guarantee that the Fund will achieve its investment objective. It is possible to lose money by investing in the Fund. The Fund is designed to be a long-term investment vehicle and is not suited for short-term trading. Investors in the Fund should have a long-term investment perspective and be able to tolerate potentially sharp declines in value. Purchase and redemption activities by Fund shareholders may impact the management of the Fund and its ability to achieve its investment objective(s). In addition, the redemption by one or more large shareholders or groups of shareholders of their holdings in the Fund could have an adverse impact on the remaining shareholders in the Fund. The Fund relies on various service providers, including the investment adviser, in its operations and is susceptible to operational, information security and related events (such as cyber or hacking attacks) that may affect the service providers or the services that they provide to the Fund. An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Risk, Lose Money rr_RiskLoseMoney The Fund is not a complete investment program and there is no guarantee that the Fund will achieve its investment objective. It is possible to lose money by investing in the Fund.
Risk, Not Insured Depository Institution rr_RiskNotInsuredDepositoryInstitution An investment in the Fund is not a deposit in a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency.
Bar Chart and Performance Table, Heading rr_BarChartAndPerformanceTableHeading Performance
Performance, Narrative rr_PerformanceNarrativeTextBlock

The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of two broad-based securities market indices. The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower. Past performance (both before and after taxes) is not necessarily an indication of how the Fund will perform in the future. The Fund’s performance reflects the effects of expense reductions. Absent these reductions, performance would have been lower. Updated Fund performance information can be obtained by visiting www.eatonvance.com.
Performance, Information Illustrates Variability of Returns rr_PerformanceInformationIllustratesVariabilityOfReturns The following bar chart and table provide some indication of the risks of investing in the Fund by showing changes in the Fund’s performance from year to year and how the Fund’s average annual returns over time compare with those of two broad-based securities market indices.
Performance Availability Website Address rr_PerformanceAvailabilityWebSiteAddress www.eatonvance.com
Performance Past Does Not Indicate Future rr_PerformancePastDoesNotIndicateFuture Past performance (both before and after taxes) is not necessarily an indication of how the Fund will perform in the future.
Bar Chart Does Not Reflect Sales Loads rr_BarChartDoesNotReflectSalesLoads The returns in the bar chart are for Class A shares and do not reflect a sales charge. If the sales charge was reflected, the returns would be lower.
Bar Chart, Closing rr_BarChartClosingTextBlock

For the ten years ended December 31, 2018, the highest quarterly total return for Class A was 14.87% for the quarter ended March 31, 2013, and the lowest quarterly return was -12.10% for the quarter ended September 30, 2015. The year-to-date total return through the end of the most recent calendar quarter (December 31, 2018 to September 30, 2019) was 11.08%.
Year to Date Return, Label rr_YearToDateReturnLabel The year-to-date total return through the end of the most recent calendar quarter (December 31, 2018 to September 30, 2019) was
Bar Chart, Year to Date Return, Date rr_BarChartYearToDateReturnDate Sep. 30, 2019
Bar Chart, Year to Date Return rr_BarChartYearToDateReturn 11.08%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel For the ten years ended December 31, 2018, the highest quarterly total return for Class A was
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Mar. 31, 2013
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 14.87%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel and the lowest quarterly return was
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Sep. 30, 2015
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (12.10%)
Performance Table Heading rr_PerformanceTableHeading Average Annual Total Return as of December 31, 2018
Performance Table Does Reflect Sales Loads rr_PerformanceTableDoesReflectSalesLoads These returns reflect the maximum sales charge for Class A (5.75%) and any applicable contingent deferred sales charge (“CDSC”) for Class C.
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate After-tax returns are calculated using the highest historical individual federal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions, and may differ from those shown.
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred After-tax returns are not relevant to shareholders who hold shares in tax-deferred accounts or to shares held by non-taxable entities.
Performance Table One Class of after Tax Shown rr_PerformanceTableOneClassOfAfterTaxShown After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher Return After Taxes on Distributions for a period may be the same as Return Before Taxes for that period because no taxable distributions were made during that period. Also, Return After Taxes on Distributions and the Sale of Fund Shares for a period may be greater than or equal to Return Before Taxes and/or Return After Taxes on Distributions for the same period because of losses realized on the sale of Fund shares.
Performance Table Footnotes, Reason Performance Information for Class Different from Immediately Preceding Period [Text] rr_PerformanceTableFootnotesReasonPerformanceInformationForClassDifferentFromImmediatelyPrecedingPeriod The Class I performance shown above for the period prior to October 1, 2009 (commencement of operations) is the performance of Class A shares at net asset value without adjustment for any differences in the expenses of the two classes. If adjusted for such differences, returns would be different.
Performance Table, Closing rr_PerformanceTableClosingTextBlock

These returns reflect the maximum sales charge for Class A (5.75%) and any applicable contingent deferred sales charge (“CDSC”) for Class C. The Class I performance shown above for the period prior to October 1, 2009 (commencement of operations) is the performance of Class A shares at net asset value without adjustment for any differences in the expenses of the two classes. If adjusted for such differences, returns would be different. S&P Dow Jones Indices are a product of S&P Dow Jones Indices LLC (“S&P DJI”) and have been licensed for use. S&P® and S&P 500® are registered trademarks of S&P DJI; Dow Jones® is a registered trademark of Dow Jones Trademark Holdings LLC (“Dow Jones”); S&P DJI, Dow Jones and their respective affiliates do not sponsor, endorse, sell or promote the Fund, will not have any liability with respect thereto and do not have any liability for any errors, omissions, or interruptions of the S&P Dow Jones Indices. (Source for MSCI World Health Care Index: MSCI.) MSCI data may not be reproduced or used for any other purpose. MSCI provides no warranties, has not prepared or approved this data, and has no liability hereunder. Investors cannot invest directly in an Index.

After-tax returns are calculated using the highest historical individual federal income tax rates and do not reflect the impact of state and local taxes. Actual after-tax returns depend on a shareholder’s tax situation and the actual characterization of distributions, and may differ from those shown. After-tax returns are not relevant to shareholders who hold shares in tax-deferred accounts or to shares held by non-taxable entities. After-tax returns for other Classes of shares will vary from the after-tax returns presented for Class A shares. Return After Taxes on Distributions for a period may be the same as Return Before Taxes for that period because no taxable distributions were made during that period. Also, Return After Taxes on Distributions and the Sale of Fund Shares for a period may be greater than or equal to Return Before Taxes and/or Return After Taxes on Distributions for the same period because of losses realized on the sale of Fund shares.
Eaton Vance Worldwide Health Sciences Fund | MSCI World Health Care Index (reflects net dividends, which reflect the deduction of withholding taxes)  
Risk/Return: rr_RiskReturnAbstract  
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects net dividends, which reflect the deduction of withholding taxes)
One Year rr_AverageAnnualReturnYear01 2.51%
Five Years rr_AverageAnnualReturnYear05 7.57%
Ten Years rr_AverageAnnualReturnYear10 11.88%
Eaton Vance Worldwide Health Sciences Fund | S&P 500 Index (reflects no deduction for fees, expenses or taxes)  
Risk/Return: rr_RiskReturnAbstract  
Index No Deduction for Fees, Expenses, Taxes rr_IndexNoDeductionForFeesExpensesTaxes (reflects no deduction for fees, expenses or taxes)
One Year rr_AverageAnnualReturnYear01 (4.38%)
Five Years rr_AverageAnnualReturnYear05 8.49%
Ten Years rr_AverageAnnualReturnYear10 13.11%
Eaton Vance Worldwide Health Sciences Fund | Class A  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice 5.75%
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of net asset value at purchase or redemption) rr_MaximumDeferredSalesChargeOverOther none
Management Fees rr_ManagementFeesOverAssets 0.72% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.25%
Other Expenses rr_OtherExpensesOverAssets 0.19%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.16%
Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [1],[2]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.09%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination December 31, 2020
1 Year rr_ExpenseExampleYear01 $ 680
3 Years rr_ExpenseExampleYear03 916
5 Years rr_ExpenseExampleYear05 1,170
10 Years rr_ExpenseExampleYear10 1,897
1 Year rr_ExpenseExampleNoRedemptionYear01 680
3 Years rr_ExpenseExampleNoRedemptionYear03 916
5 Years rr_ExpenseExampleNoRedemptionYear05 1,170
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,897
Annual Return 2009 rr_AnnualReturn2009 9.89%
Annual Return 2010 rr_AnnualReturn2010 11.13%
Annual Return 2011 rr_AnnualReturn2011 4.75%
Annual Return 2012 rr_AnnualReturn2012 15.49%
Annual Return 2013 rr_AnnualReturn2013 44.56%
Annual Return 2014 rr_AnnualReturn2014 27.39%
Annual Return 2015 rr_AnnualReturn2015 8.39%
Annual Return 2016 rr_AnnualReturn2016 (14.89%)
Annual Return 2017 rr_AnnualReturn2017 16.24%
Annual Return 2018 rr_AnnualReturn2018 5.98%
One Year rr_AverageAnnualReturnYear01 (0.13%)
Five Years rr_AverageAnnualReturnYear05 6.40%
Ten Years rr_AverageAnnualReturnYear10 11.28%
Eaton Vance Worldwide Health Sciences Fund | Class A | After Taxes on Distributions  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 (1.11%)
Five Years rr_AverageAnnualReturnYear05 4.13%
Ten Years rr_AverageAnnualReturnYear10 9.16%
Eaton Vance Worldwide Health Sciences Fund | Class A | After Taxes on Distributions and Sales  
Risk/Return: rr_RiskReturnAbstract  
One Year rr_AverageAnnualReturnYear01 1.05%
Five Years rr_AverageAnnualReturnYear05 4.63%
Ten Years rr_AverageAnnualReturnYear10 8.97%
Eaton Vance Worldwide Health Sciences Fund | Class C  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of net asset value at purchase or redemption) rr_MaximumDeferredSalesChargeOverOther 1.00%
Management Fees rr_ManagementFeesOverAssets 0.72% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 1.00%
Other Expenses rr_OtherExpensesOverAssets 0.19%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.91%
Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [1],[2]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.84%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination December 31, 2020
1 Year rr_ExpenseExampleYear01 $ 287
3 Years rr_ExpenseExampleYear03 593
5 Years rr_ExpenseExampleYear05 1,025
10 Years rr_ExpenseExampleYear10 2,227
1 Year rr_ExpenseExampleNoRedemptionYear01 187
3 Years rr_ExpenseExampleNoRedemptionYear03 593
5 Years rr_ExpenseExampleNoRedemptionYear05 1,025
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 2,227
One Year rr_AverageAnnualReturnYear01 4.25%
Five Years rr_AverageAnnualReturnYear05 6.88%
Ten Years rr_AverageAnnualReturnYear10 11.10%
Eaton Vance Worldwide Health Sciences Fund | Class I  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of net asset value at purchase or redemption) rr_MaximumDeferredSalesChargeOverOther none
Management Fees rr_ManagementFeesOverAssets 0.72% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets none
Other Expenses rr_OtherExpensesOverAssets 0.19%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 0.91%
Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [1],[2]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 0.84%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination December 31, 2020
1 Year rr_ExpenseExampleYear01 $ 86
3 Years rr_ExpenseExampleYear03 283
5 Years rr_ExpenseExampleYear05 497
10 Years rr_ExpenseExampleYear10 1,113
1 Year rr_ExpenseExampleNoRedemptionYear01 86
3 Years rr_ExpenseExampleNoRedemptionYear03 283
5 Years rr_ExpenseExampleNoRedemptionYear05 497
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,113
One Year rr_AverageAnnualReturnYear01 6.29%
Five Years rr_AverageAnnualReturnYear05 7.95%
Ten Years rr_AverageAnnualReturnYear10 12.20%
Inception Date rr_AverageAnnualReturnInceptionDate Oct. 01, 2009
Eaton Vance Worldwide Health Sciences Fund | Class R  
Risk/Return: rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price) rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Maximum Deferred Sales Charge (Load) (as a percentage of the lower of net asset value at purchase or redemption) rr_MaximumDeferredSalesChargeOverOther none
Management Fees rr_ManagementFeesOverAssets 0.72% [1]
Distribution and Service (12b-1) Fees rr_DistributionAndService12b1FeesOverAssets 0.50%
Other Expenses rr_OtherExpensesOverAssets 0.19%
Total Annual Fund Operating Expenses rr_ExpensesOverAssets 1.41%
Expense Reimbursement rr_FeeWaiverOrReimbursementOverAssets (0.07%) [1],[2]
Total Annual Fund Operating Expenses After Expense Reimbursement rr_NetExpensesOverAssets 1.34%
Fee Waiver or Reimbursement over Assets, Date of Termination rr_FeeWaiverOrReimbursementOverAssetsDateOfTermination December 31, 2020
1 Year rr_ExpenseExampleYear01 $ 136
3 Years rr_ExpenseExampleYear03 439
5 Years rr_ExpenseExampleYear05 764
10 Years rr_ExpenseExampleYear10 1,685
1 Year rr_ExpenseExampleNoRedemptionYear01 136
3 Years rr_ExpenseExampleNoRedemptionYear03 439
5 Years rr_ExpenseExampleNoRedemptionYear05 764
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,685
One Year rr_AverageAnnualReturnYear01 5.82%
Five Years rr_AverageAnnualReturnYear05 7.42%
Ten Years rr_AverageAnnualReturnYear10 11.66%
[1] "Management Fees" reflect a base contractual advisory fee of 0.63%, a performance fee adjustment decrease of 0.06% (based on the performance fee adjustment for the most recent fiscal year) and an administrative fee of 0.15%. See page 14 of this Prospectus for more information about the calculation of the performance fee adjustment.
[2] The investment adviser, sub-adviser and administrator have agreed to reimburse the Fund's expenses to the extent that Total Annual Fund Operating Expenses exceed 1.15% for Class A shares, 1.90% for Class C shares, 0.90% for Class I shares and 1.40% for Class R shares. This expense reimbursement will continue through December 31, 2020. Any amendment to or termination of this reimbursement would require approval of the Board of Trustees. The expense reimbursement relates to ordinary operating expenses only and does not include expenses such as: brokerage commissions, acquired fund fees and expenses of unaffiliated funds, any performance-based adjustment to an asset-based investment advisory fee, borrowing costs (including borrowing costs of any acquired funds), taxes or litigation expenses. Amounts reimbursed may be recouped by the investment adviser, sub-adviser and administrator during the same fiscal year to the extent actual expenses are less than the contractual expense cap during such year.