v3.25.1
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Risk Return Abstract rr_RiskReturnAbstract  
Registrant Name dei_EntityRegistrantName First Trust Exchange-Traded Fund
Prospectus Date rr_ProspectusDate May 01, 2025
First Trust WCM Developing World Equity ETF  
Risk Return Abstract rr_RiskReturnAbstract  
Risk/Return [Heading] rr_RiskReturnHeading <span style="font-family:Arial;font-size:12.60pt;font-weight:bold;">First Trust WCM Developing World Equity ETF (WCME)</span>
Objective [Heading] rr_ObjectiveHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Investment Objective</span>
Objective, Primary [Text Block] rr_ObjectivePrimaryTextBlock The First Trust WCM Developing World Equity ETF (the "Fund") seeks to provide investors with long-term capital appreciation.
Expense [Heading] rr_ExpenseHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Fees and Expenses of the Fund</span>
Expense Narrative [Text Block] rr_ExpenseNarrativeTextBlock The following table describes the fees and expenses you may pay if you buy, hold and sell shares of the Fund. Investors may pay other fees, such as brokerage commissions and other fees to financial intermediaries, which are not reflected in the table and example below.
Shareholder Fees Caption [Text] rr_ShareholderFeesCaption <span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;">Shareholder Fees</span> <br/><span style="color:#000000;font-family:Arial;font-size:9.00pt;">(fees paid directly from your investment)</span>
Operating Expenses Caption [Text] rr_OperatingExpensesCaption <span style="color:#000000;font-family:Arial;font-size:9.00pt;font-weight:bold;">Annual Fund Operating Expenses</span> <br/><span style="color:#000000;font-family:Arial;font-size:9.00pt;">(expenses that you pay each year as a percentage of the value of your investment)</span>
Portfolio Turnover [Heading] rr_PortfolioTurnoverHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Portfolio Turnover</span>
Portfolio Turnover [Text Block] rr_PortfolioTurnoverTextBlock The Fund pays transaction costs, such as commissions, when it buys and sells securities (or “turns over” its 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. As a result of a reorganization (the “Reorganization”), the Fund acquired all of the assets, subject to the liabilities, of WCM Developing World Equity Fund, an open-end management company and a series of Investment Managers Series Trust (the “Predecessor Fund”). During the most recent fiscal year, the Fund's portfolio turnover rate was 85% of the average value of its portfolio.
Portfolio Turnover, Rate rr_PortfolioTurnoverRate 85.00%
Expense Example [Heading] rr_ExpenseExampleHeading <span style="font-family:Arial;font-size:9.00pt;font-style:italic;font-weight:bold;">Example</span>
Expense Example, No Redemption Narrative [Text Block] rr_ExpenseExampleNoRedemptionNarrativeTextBlock The example below is intended to help you compare the cost of investing in the Fund with the cost of investing in other funds.The example assumes that you invest $10,000 in the Fund for the time periods indicated and then hold or sell all of your shares at the end of those periods. The example also assumes that your investment has a 5% return each year and that the Fund’s operating expenses remain at current levels. Although your actual costs may be higher or lower, based on these assumptions your costs would be:
Strategy [Heading] rr_StrategyHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Principal Investment Strategies</span>
Strategy Narrative [Text Block] rr_StrategyNarrativeTextBlock Under normal circumstances, the Fund will invest at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of companies located in developing countries. Such equity securities may include common stock and depositary receipts (including American Depositary Receipts (“ADRs”), European Depositary Receipts (“EDRs”), Canadian Depositary Receipts (“CDRs”) and Global Depositary Receipts (“GDRs”)). ADRs and CDRs are receipts that represent interests in foreign securities held on deposit by U.S. and Canadian banks or trust companies, respectively. EDRs and GDRs have the same qualities as ADRs, although they may be traded in several international trading markets. The Fund may also invest in securities denominated in non-U.S. currencies and securities of companies domiciled in China that list and trade directly on Chinese stock exchanges (“China A Shares”). In determining whether a country is a developing country, the Fund’s investment sub-advisor, WCM Investment Management, LLC (the “Sub-Advisor”), will consider, among other things: (i) whether the country is considered to be a developing country as classified by the World Bank or included in any of the Morgan Stanley Capital International (MSCI) emerging markets or frontier markets indices; (ii) the country’s per capita gross domestic product; (iii) the percentage of the country’s economy that is industrialized; (iv) market capitalization as a percentage of the country’s gross domestic product; and (v) the overall regulatory environment of the country, including the presence of governmental regulation limiting or banning foreign ownership and restrictions on repatriation of initial capital, dividends, interest and/or capital gains. For example, the Sub-Advisor expects that most countries classified by the World Bank as having low- to middle-income economies, or that are included in any of the Morgan Stanley Capital International (“MSCI”) emerging markets or frontier markets indices, will be treated as developing countries. The Sub-Advisor considers a company to be located in a country: (i) if the company has been organized under the laws of, has its principal offices in, or has its securities principally traded in, the country; or (ii) if the company derives at least 50% of its revenues or net profits from, or has at least 50% of its assets or production capacities in, the country. Under normal market conditions, the Fund invests in the equity securities of companies located in at least three different countries outside of the United States, and the Fund may invest in securities of any market capitalization. From time to time, the Fund may invest a significant portion of its assets in the securities of companies located in one or a few developing countries or regions. The Sub-Advisor’s investment process begins with bottom-up, fundamental research, which involves examining and ranking companies based on the following factors: (i) the company’s corporate performance; (ii) the company’s competitive position; (iii) the company’s potential future growth; and (iv) the company’s intrinsic value, which is determined using a discounted cash flow model, historical EV/EBITDA (compares a company’s Enterprise Value (the measure of a company’s total value) to its Earnings Before Interest, Taxes, Depreciation and Amortization), and next year price to earnings ratio. The Sub-Advisor’s fundamental research also involves an analysis of the company’s environmental, social and governance (“ESG”) characteristics. In the Sub-Advisor’s view, industry specific material ESG factors can have an impact on the short or long-term financial performance of a company, however, integrating ESG considerations into the research process does not make ESG information the primary consideration for an investment decision. As of March 31, 2025, the Fund had significant investments in financial companies, information technology companies, Latin American issuers and Asian issuers, although this may change from time to time. Over time, the Fund may have significant investments in a jurisdiction or investment sector that it may not have had as of March 31, 2025. To the extent the Fund invests a significant portion of its assets in a given jurisdiction or investment sector, the Fund may be exposed to the risks associated with that jurisdiction or investment sector. The Fund will not invest 25% or more of the value of its total assets in securities of issuers in any one industry or group of industries. The Fund is classified as “non-diversified” under the Investment Company Act of 1940, as amended (the “1940 Act”).
Strategy Portfolio Concentration [Text] rr_StrategyPortfolioConcentration <span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">As of March 31, 2025, the Fund had significant investments in financial companies, information technology companies, Latin American issuers </span><span style="font-family:Arial;font-size:9.00pt;">and Asian issuers, although this may change from time to time.</span>
Risk [Heading] rr_RiskHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Principal Risks</span>
Risk Caption rr_RiskCaption <span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">You could lose money by investing in the Fund.</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">An investment in the Fund is not a deposit of a bank and is not insured or </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;"> There can be no assurance that </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">the Fund’s investment objective will be achieved. The order of the below risk factors does not indicate the significance of any </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">particular risk factor.</span>
Bar Chart and Performance Table [Heading] rr_BarChartAndPerformanceTableHeading <span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Annual Total Return</span>
Performance Narrative [Text Block] rr_PerformanceNarrativeTextBlock The shareholders of the Predecessor Fund approved an Agreement and Plan of Reorganization (the “Plan”) by and between the Predecessor Fund and the Trust, on behalf the Fund, pursuant to which the Predecessor Fund would (i) transfer all of its assets to the Fund in exchange solely for newly issued shares of the Fund and the Fund’s assumption of all of the liabilities of the Predecessor Fund, and (ii) immediately distribute such newly issued shares of the Fund to shareholders of the Predecessor Fund (the “Reorganization”). As a result of the Reorganization, the Fund has assumed the performance history of the Predecessor Fund. The bar chart and table below provide some indication of the risks of investing in the Predecessor Fund by showing you how the performance of the Predecessor Fund has varied from year to year, from its inception on March 31, 2020 until the date of the Reorganization on October 7, 2024. While the Predecessor Fund and Fund have investment policies and practices that are substantially similar, the Predecessor Fund’s past performance is not necessarily indicative of how the Fund will perform in the future. Accordingly, any Fund performance and historical returns shown below that incorporate Predecessor Fund performance prior to October 7, 2024 are not necessarily indicative of the performance that the Fund would have generated.The bar chart and table below illustrate the annual calendar year returns of the Fund (having assumed the performance of the Predecessor Fund) based on net asset value as well as the average annual Fund returns. The bar chart and table provide an indication of the risks of investing in the Fund by showing changes in the Fund’s performance (having assumed the performance of the Predecessor Fund) from year-to-year and by showing how the Fund’s average annual total returns based on net asset value compared to those of a market index.The Fund’s performance information is accessible on the Fund’s website at http://www.ftportfolios.com.
Performance Information Illustrates Variability of Returns [Text] rr_PerformanceInformationIllustratesVariabilityOfReturns <span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">The bar chart and table below illustrate the annual calendar year returns of the Fund (having assumed the performance of the Predecessor Fund) based on net asset value as well as the average annual Fund returns. The </span><span style="font-family:Arial;font-size:9.00pt;">bar chart and table provide </span><span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">an indication of the risks of investing in the Fund by showing changes in the Fund’s performance (having assumed the performance of the Predecessor Fund) from year-to-year and by showing </span><span style="font-family:Arial;font-size:9.00pt;">how the Fund’s average annual total returns based </span><span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">on net asset value compared to those of a market index.</span>
Performance Availability Website Address [Text] rr_PerformanceAvailabilityWebSiteAddress <span style="font-family:Arial;font-size:9.00pt;">http://www.ftportfolios.com</span>
Performance Past Does Not Indicate Future [Text] rr_PerformancePastDoesNotIndicateFuture <span style="color:#000000;font-family:Arial;font-size:9.00pt;">The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.</span>
Bar Chart [Heading] rr_BarChartHeading <span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">First Trust WCM Developing World Equity ETF</span> <br/><span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">Calendar Year Total Returns as of 12/31</span>
Bar Chart Closing [Text Block] rr_BarChartClosingTextBlock During the periods shown in the chart above:ReturnPeriod EndedBest Quarter15.29%December 31, 2022Worst Quarter-13.48%June 30, 2022
Performance Table Heading rr_PerformanceTableHeading <span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">Average Annual Total Returns for the Periods Ended December 31, 2024</span>
Performance Table Uses Highest Federal Rate rr_PerformanceTableUsesHighestFederalRate <span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">All after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of any state or local tax.</span>
Performance Table Not Relevant to Tax Deferred rr_PerformanceTableNotRelevantToTaxDeferred <span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0%;">Your own actual after-tax returns will depend on your specific tax situation and may differ from what is shown here. After-tax returns are not relevant to investors who hold Fund shares in tax-deferred accounts such as individual retirement accounts </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">(</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;font-style:italic;">IRAs</span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">) or employee-sponsored retirement plans.</span>
Performance Table Explanation after Tax Higher rr_PerformanceTableExplanationAfterTaxHigher <span style="font-family:Arial;font-size:9.00pt;">Returns after taxes on distributions reflect the taxed return on the payment of dividends </span><span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">and capital gains. Returns after taxes on distributions and sale of shares assume you sold your shares at period end, and, therefore, are also adjusted for any capital gains or losses incurred. Returns for </span><span style="font-family:Arial;font-size:9.00pt;">an index do not include expenses, which are deducted from Fund returns, or taxes.</span>
Performance Table Narrative rr_PerformanceTableNarrativeTextBlock The Fund’s past performance (before and after taxes) is not necessarily an indication of how the Fund will perform in the future.All after-tax returns are calculated using the historical highest individual federal marginal income tax rates and do not reflect the impact of any state or local tax.Returns after taxes on distributions reflect the taxed return on the payment of dividends and capital gains. Returns after taxes on distributions and sale of shares assume you sold your shares at period end, and, therefore, are also adjusted for any capital gains or losses incurred. Returns for an index do not include expenses, which are deducted from Fund returns, or taxes.Your own actual after-tax returns will depend on your specific tax situation and may differ from what is shown here. After-tax returns are not relevant to investors who hold Fund shares in tax-deferred accounts such as individual retirement accounts (IRAs) or employee-sponsored retirement plans.
First Trust WCM Developing World Equity ETF | Risk Lose Money [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock You could lose money by investing in the Fund.
First Trust WCM Developing World Equity ETF | Risk Not Insured Depository Institution [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock An investment in the Fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other governmental agency.
First Trust WCM Developing World Equity ETF | Asia Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock ASIA RISK. The Fund is subject to certain risks specifically associated with investments in the securities of Asian issuers. Many Asian economies have experienced rapid growth and industrialization, and there is no assurance that this growth rate will be maintained. Some Asian economies are highly dependent on trade, and economic conditions in other countries within and outside Asia can impact these economies. Certain of these economies may be adversely affected by trade or policy disputes with its major trade partners. There is also a high concentration of market capitalization and trading volume in a small number of issuers representing a limited number of industries, as well as a high concentration of investors and financial intermediaries. Certain Asian countries have experienced and may in the future experience expropriation and nationalization of assets, confiscatory taxation, currency manipulation, political instability, armed conflict and social instability as a result of religious, ethnic, socio-economic and/or political unrest. In particular, escalated tensions involving North Korea and any outbreak of hostilities involving North Korea could have a severe adverse effect on Asian economies. Governments of certain Asian countries have exercised, and continue to exercise, substantial influence over many aspects of the private sector. In certain cases, the government owns or controls many companies, including the largest in the country. Accordingly, government actions could have a significant effect on the issuers of the Fund’s securities or on economic conditions generally. Recent developments in relations between the U.S. and China have heightened concerns of increased tariffs and restrictions on trade between the two countries. An increase in tariffs or trade restrictions, or even the threat of such developments, could lead to a significant reduction in international trade, which could have a negative impact on the economy of Asian countries and a commensurately negative impact on the Fund.
First Trust WCM Developing World Equity ETF | Authorized Participant Concentration Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock AUTHORIZED PARTICIPANT CONCENTRATION RISK. Only an authorized participant may engage in creation or redemption transactions directly with the Fund. A limited number of institutions act as authorized participants for the Fund. To the extent that these institutions exit the business or are unable to proceed with creation and/or redemption orders and no other authorized participant steps forward to create or redeem, the Fund’s shares may trade at a premium or discount (the difference between the market price of the Fund's shares and the Fund's net asset value) and possibly face delisting and the bid/ask spread (the difference between the price that someone is willing to pay for shares of the Fund at a specific point in time versus the price at which someone is willing to sell) on the Fund’s shares may widen.
First Trust WCM Developing World Equity ETF | China A Share Investment Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CHINA A SHARE INVESTMENT RISK. Investing in China A-shares through a Stock Connect is subject to trading, clearance, settlement and other procedures, which could pose risks to the Fund. Trading through a Stock Connect is subject to a daily quota, which may restrict or preclude the Fund’s ability to invest in Stock Connect securities. Foreign investors, individually and in the aggregate, are subject to ownership limitations on China exchange-listed companies, including those purchased through a Stock Connect. Once the daily quota is reached, orders to purchase additional China A Shares through a Stock Connect Program will be rejected. As such, China A Shares are subject to trading restrictions and suspensions, quota limitations and sudden changes in those limitations, and operational, clearing and settlement risks. Significant portions of the Chinese securities markets may become rapidly illiquid, as Chinese issuers have the ability to suspend the trading of their equity securities, and have shown a willingness to exercise that option in response to market volatility and other events. The liquidity of Chinese listed securities may shrink or disappear suddenly and without warning as a result of adverse economic, market or political events, or adverse investor perceptions, whether or not accurate. Any of the above circumstances could have a significant negative impact on the value of China A Shares held by the Fund.
First Trust WCM Developing World Equity ETF | Currency Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CURRENCY RISK. Changes in currency exchange rates affect the value of investments denominated in a foreign currency, the value of dividends and interest earned from such securities and gains and losses realized on the sale of such securities, and therefore the value of such investments or dividends in the Fund’s portfolio. The Fund’s net asset value could decline if a currency to which the Fund has exposure depreciates against the U.S. dollar or if there are delays or limits on repatriation of such currency. Currency exchange rates can be very volatile and can change quickly and unpredictably. As a result, the value of an investment in the Fund may change quickly and without warning.
First Trust WCM Developing World Equity ETF | Current Market Conditions Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CURRENT MARKET CONDITIONS RISK. Current market conditions risk is the risk that a particular investment, or shares of the Fund in general, may fall in value due to current market conditions. As a means to fight inflation, which remains at elevated levels, the Federal Reserve and certain foreign central banks have raised interest rates; however, the Federal Reserve has recently lowered interest rates and may continue to do so. U.S. regulators have proposed several changes to market and issuer regulations which would directly impact the Fund, and any regulatory changes could adversely impact the Fund’s ability to achieve its investment strategies or make certain investments. Recent and potential future bank failures could result in disruption to the broader banking industry or markets generally and reduce confidence in financial institutions and the economy as a whole, which may also heighten market volatility and reduce liquidity. Additionally, challenges in commercial real estate markets, including rising interest rates, declining valuations and increasing vacancies, could have a broader impact on financial markets. The ongoing adversarial political climate in the United States, as well as political and diplomatic events both domestic and abroad, have and may continue to have an adverse impact the U.S. regulatory landscape, markets and investor behavior, which could have a negative impact on the Fund’s investments and operations. The change in administration resulting from the 2024 United States national elections could result in significant impacts to international trade relations, tax and immigration policies, and other aspects of the national and international political and financial landscape, which could affect, among other things, inflation and the securities markets generally. Other unexpected political, regulatory and diplomatic events within the U.S. and abroad may affect investor and consumer confidence and may adversely impact financial markets and the broader economy. For example, ongoing armed conflicts between Russia and Ukraine in Europe and among Israel, Iran, Hamas and other militant groups in the Middle East, have caused and could continue to cause significant market disruptions and volatility within the markets in Russia, Europe, the Middle East and the United States. The hostilities and sanctions resulting from those hostilities have and could continue to have a significant impact on certain Fund investments as well as Fund performance and liquidity. The economies of the United States and its trading partners, as well as the financial markets generally, may be adversely impacted by trade disputes, including the imposition of tariffs, and other matters. For example, the United States has imposed trade barriers and restrictions on China. In addition, the Chinese government is engaged in a longstanding dispute with Taiwan, continually threatening an invasion. If the political climate between the United States and China does not improve or continues to deteriorate, if China were to attempt invading Taiwan, or if other geopolitical conflicts develop or worsen, economies, markets and individual securities may be adversely affected, and the value of the Fund’s assets may go down. A public health crisis and the ensuing policies enacted by governments and central banks may cause significant volatility and uncertainty in global financial markets, negatively impacting global growth prospects. As the COVID-19 global pandemic illustrated, such events may affect certain geographic regions, countries, sectors and industries more significantly than others. Advancements in technology may also adversely impact markets and the overall performance of the Fund. For instance, the economy may be significantly impacted by the advanced development and increased regulation of artificial intelligence. Additionally, cyber security breaches of both government and non-government entities could have negative impacts on infrastructure and the ability of such entities, including the Fund, to operate properly. These events, and any other future events, may adversely affect the prices and liquidity of the Fund’s portfolio investments and could result in disruptions in the trading markets.
First Trust WCM Developing World Equity ETF | Cyber Security Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock CYBER SECURITY RISK. The Fund is susceptible to operational risks through breaches in cyber security. A breach in cyber security refers to both intentional and unintentional events that may cause the Fund to lose proprietary information, suffer data corruption or lose operational capacity. Such events could cause the Fund to incur regulatory penalties, reputational damage, additional compliance costs associated with corrective measures and/or financial loss. Cyber security breaches may involve unauthorized access to the Fund’s digital information systems through “hacking” or malicious software coding but may also result from outside attacks such as denial-of-service attacks through efforts to make network services unavailable to intended users. In addition, cyber security breaches of the issuers of securities in which the Fund invests or the Fund’s third-party service providers, such as its administrator, transfer agent, custodian, or sub-advisor, as applicable, can also subject the Fund to many of the same risks associated with direct cyber security breaches. Although the Fund has established risk management systems designed to reduce the risks associated with cyber security, there is no guarantee that such efforts will succeed, especially because the Fund does not directly control the cyber security systems of issuers or third-party service providers.
First Trust WCM Developing World Equity ETF | Depositary Receipts Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock DEPOSITARY RECEIPTS RISK. Depositary receipts represent equity interests in a foreign company that trade on a local stock exchange. Depositary receipts may be less liquid than the underlying shares in their primary trading market. Any distributions paid to the holders of depositary receipts are usually subject to a fee charged by the depositary. Holders of depositary receipts may have limited voting rights, and investment restrictions in certain countries may adversely impact the value of depositary receipts because such restrictions may limit the ability to convert the equity shares into depositary receipts and vice versa. Such restrictions may cause the equity shares of the underlying issuer to trade at a discount or premium to the market price of the depositary receipts.
First Trust WCM Developing World Equity ETF | Emerging Markets Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock EMERGING MARKETS RISK. Investments in securities issued by governments and companies operating in emerging market countries involve additional risks relating to political, economic, or regulatory conditions not associated with investments in securities and instruments issued by U.S. companies or by companies operating in other developed market countries. Investments in emerging markets securities are generally considered speculative in nature and are subject to the following heightened risks: smaller market capitalization of securities markets which may suffer periods of relative illiquidity; market manipulation; significant price volatility; restrictions on foreign investment; possible repatriation of investment income and capital; rapid inflation; and currency convertibility issues. Emerging market countries also often have less uniformity in accounting, auditing and reporting requirements, unsettled securities laws, unreliable securities valuation and greater risk associated with custody of securities. Financial and other reporting by companies and government entities also may be less reliable in emerging market countries. Shareholder claims that are available in the U.S., as well as regulatory oversight and authority that is common in the U.S., including for claims based on fraud, may be difficult or impossible for shareholders of securities in emerging market countries or for U.S. authorities to pursue. Furthermore, investors may be required to register the proceeds of sales and future economic or political crises could lead to price controls, forced mergers, expropriation or confiscatory taxation, seizure, nationalization or creation of government monopolies.
First Trust WCM Developing World Equity ETF | Equity Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock EQUITY SECURITIES RISK. The value of the Fund's shares will fluctuate with changes in the value of the equity securities in which it invests. Equity securities prices fluctuate for several reasons, including changes in investors’ perceptions of the financial condition of an issuer or the general condition of the relevant equity market, such as market volatility, or when political or economic events affecting an issuer occur. Common stock prices may be particularly sensitive to rising interest rates, as the cost of capital rises and borrowing costs increase. Equity securities may decline significantly in price over short or extended periods of time, and such declines may occur in the equity market as a whole, or they may occur in only a particular country, company, industry or sector of the market.
First Trust WCM Developing World Equity ETF | Financial Companies Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock FINANCIAL COMPANIES RISK. Financial companies, such as retail and commercial banks, insurance companies and financial services companies, are especially subject to the adverse effects of economic recession, currency exchange rates, extensive government regulation, decreases in the availability of capital, volatile interest rates, portfolio concentrations in geographic markets, industries or products (such as commercial and residential real estate loans), competition from new entrants and blurred distinctions in their fields of business.
First Trust WCM Developing World Equity ETF | Frontier Markets Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock FRONTIER MARKETS RISK. Frontier market countries generally have smaller economies and even less developed capital markets than traditional emerging markets, and, as a result, the risks of investing in emerging market countries are magnified in frontier market countries. The magnification of risks is the result of potential for extreme price volatility and illiquidity in frontier markets; government ownership or control of parts of private sector and of certain companies; trade barriers, exchange controls, managed adjustments in relative currency values and other protectionist measures imposed or negotiated by the countries with which frontier market countries trade; and the relatively new and unsettled securities laws in many frontier market countries.
First Trust WCM Developing World Equity ETF | Index Or Model Constituent Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock INDEX OR MODEL CONSTITUENT RISK. The Fund may be a constituent of one or more indices or ETF models. As a result, the Fund may be included in one or more index-tracking exchange-traded funds or mutual funds. Being a component security of such a vehicle could greatly affect the trading activity involving the Fund’s shares, the size of the Fund and the market volatility of the Fund. Inclusion in an index could increase demand for the Fund and removal from an index could result in outsized selling activity in a relatively short period of time. As a result, the Fund’s net asset value could be negatively impacted and the Fund’s market price may be below the Fund’s net asset value during certain periods. In addition, index rebalances may potentially result in increased trading activity in the Fund's shares.
First Trust WCM Developing World Equity ETF | Information Technology Companies Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock INFORMATION TECHNOLOGY COMPANIES RISK. Information technology companies produce and provide hardware, software and information technology systems and services. These companies may be adversely affected by rapidly changing technologies, short product life cycles, fierce competition, aggressive pricing and reduced profit margins, the loss of patent, copyright and trademark protections, cyclical market patterns, evolving industry standards and frequent new product introductions. In addition, information technology companies are particularly vulnerable to federal, state and local government regulation, and competition and consolidation, both domestically and internationally, including competition from foreign competitors with lower production costs. Information technology companies also heavily rely on intellectual property rights and may be adversely affected by the loss or impairment of those rights.
First Trust WCM Developing World Equity ETF | International Closed Market Trading Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock INTERNATIONAL CLOSED MARKET TRADING RISK. Because securities held by the Fund trade on non-U.S. exchanges that are closed when the Fund’s primary listing exchange is open, there are likely to be deviations between the current price of an underlying security and the last quoted price for the underlying security (i.e., the Fund’s quote from the closed foreign market) used for purposes of calculating the Fund's net asset value, resulting in premiums or discounts to the Fund’s net asset value that may be greater than those experienced by other exchange-traded funds. In addition, shareholders may not be able to purchase and sell shares of the Fund on the listing exchange for the Fund, on days when the net asset value of the Fund could be significantly affected by events in the relevant foreign markets.
First Trust WCM Developing World Equity ETF | Large Capitalization Companies Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock LARGE CAPITALIZATION COMPANIES RISK. Large capitalization companies may grow at a slower rate and be less able to adapt to changing market conditions than smaller capitalization companies. Thus, the return on investment in securities of large capitalization companies may be less than the return on investment in securities of small and/or mid capitalization companies. The performance of large capitalization companies also tends to trail the overall market during different market cycles.
First Trust WCM Developing World Equity ETF | Latin America Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock LATIN AMERICA RISK. The Fund is subject to certain risks specifically associated with investments in the securities of Latin American issuers. The economies of Latin American countries have in the past experienced considerable difficulties, including high inflation rates, high interest rates, high unemployment, government overspending and political instability. International economic conditions, particularly those in the United States, Europe and Asia, as well as world prices for oil and other commodities may also influence the development of Latin American economies. Many Latin American countries are highly reliant on the exportation of commodities and their economies may be significantly impacted by fluctuations in commodity prices and the global demand for certain commodities. Investments in Latin American countries may be subject to currency risks, such as restrictions on the flow of money in and out of a country, extreme volatility relative to the U.S. dollar, and devaluation, all of which could decrease the value of investments in Latin American companies. Other Latin American investment risks may include inadequate investor protection, less developed regulatory, accounting, auditing and financial standards, unfavorable changes in laws or regulations, natural disasters, corruption and military activity. The governments of many Latin American countries may also exercise substantial influence over many aspects of the private sector, and any such exercise could have a significant effect on companies in which the Fund invests. Securities of companies in Latin America may also be subject to significant price volatility.
First Trust WCM Developing World Equity ETF | Liquidity Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock LIQUIDITY RISK. The Fund may hold certain investments that may be subject to restrictions on resale, trade over-the-counter or in limited volume, or lack an active trading market. Certain investments held by the Fund that trade on non-U.S. exchanges may be further subject to liquidity risk due to foreign market closures or unexpected impediments to trading in local markets. Accordingly, the Fund may not be able to sell or close out of such investments at favorable times or prices (or at all), or at the prices approximating those at which the Fund currently values them. Illiquid securities may trade at a discount from comparable, more liquid investments and may be subject to wide fluctuations in market value and the bid/ask spread on the Fund's shares may widen.
First Trust WCM Developing World Equity ETF | Management Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock MANAGEMENT RISK. The Fund is subject to management risk because it is an actively managed portfolio. In managing the Fund’s investment portfolio, the Fund's portfolio managers (listed below) will apply investment techniques and risk analyses that may not produce the desired result. There can be no guarantee that the Fund will meet its investment objective.
First Trust WCM Developing World Equity ETF | Market Maker Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock MARKET MAKER RISK. The Fund faces numerous market trading risks, including the potential lack of an active market for Fund shares due to a limited number of market markers. Decisions by market makers or authorized participants to reduce their role or step away from these activities in times of market stress could inhibit the effectiveness of the arbitrage process in maintaining the relationship between the underlying values of the Fund’s portfolio securities and the Fund’s market price. The Fund may rely on a small number of third-party market makers to provide a market for the purchase and sale of shares. Any trading halt or other problem relating to the trading activity of these market makers could result in a dramatic change in the spread between the Fund’s net asset value and the price at which the Fund’s shares are trading on the Exchange, which could result in a decrease in value of the Fund’s shares. This reduced effectiveness could result in Fund shares trading at a discount to net asset value and also in greater than normal intraday bid-ask spreads for Fund shares.
First Trust WCM Developing World Equity ETF | Market Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock MARKET RISK. Market risk is the risk that a particular investment, or shares of the Fund in general, may fall in value. Securities are subject to market fluctuations caused by real or perceived adverse economic, political, and regulatory factors or market developments, changes in interest rates and perceived trends in securities prices. Shares of the Fund could decline in value or underperform other investments. In addition, local, regional or global events such as war, acts of terrorism, market manipulation, government defaults, government shutdowns, regulatory actions, political changes, diplomatic developments, the imposition of sanctions and other similar measures, spread of infectious diseases or other public health issues, recessions, natural disasters, or other events could have a significant negative impact on the Fund and its investments. Any of such circumstances could have a materially negative impact on the value of the Fund’s shares, the liquidity of an investment, and may result in increased market volatility. During any such events, the Fund’s shares may trade at increased premiums or discounts to their net asset value, the bid/ask spread on the Fund’s shares may widen and the returns on investment may fluctuate.
First Trust WCM Developing World Equity ETF | Risk Nondiversified [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock NON-DIVERSIFICATION RISK. The Fund is classified as “non-diversified” under the 1940 Act. As a result, the Fund is only limited as to the percentage of its assets which may be invested in the securities of any one issuer by the diversification requirements imposed by the Internal Revenue Code of 1986, as amended. The Fund may invest a relatively high percentage of its assets in a limited number of issuers. As a result, the Fund may be more susceptible to a single adverse economic or regulatory occurrence affecting one or more of these issuers, experience increased volatility and be highly invested in certain issuers.
First Trust WCM Developing World Equity ETF | Non US Securities Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock NON-U.S. SECURITIES RISK. Non-U.S. securities are subject to higher volatility than securities of domestic issuers due to possible adverse political, social or economic developments, restrictions on foreign investment or exchange of securities, capital controls, lack of liquidity, currency exchange rates, excessive taxation, government seizure of assets, the imposition of sanctions by foreign governments, different legal or accounting standards, and less government supervision and regulation of securities exchanges in foreign countries.
First Trust WCM Developing World Equity ETF | Operational Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock OPERATIONAL RISK. The Fund is subject to risks arising from various operational factors, including, but not limited to, human error, processing and communication errors, errors of the Fund’s service providers, counterparties or other third-parties, failed or inadequate processes and technology or systems failures. The Fund relies on third-parties for a range of services, including custody. Any delay or failure relating to engaging or maintaining such service providers may affect the Fund’s ability to meet its investment objective. Although the Fund and the Fund's investment advisor seek to reduce these operational risks through controls and procedures, there is no way to completely protect against such risks.
First Trust WCM Developing World Equity ETF | Premium Discount Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock PREMIUM/DISCOUNT RISK. The market price of the Fund’s shares will generally fluctuate in accordance with changes in the Fund’s net asset value as well as the relative supply of and demand for shares on the Exchange. The Fund’s investment advisor cannot predict whether shares will trade below, at or above their net asset value because the shares trade on the Exchange at market prices and not at net asset value. Price differences may be due, in large part, to the fact that supply and demand forces at work in the secondary trading market for shares will be closely related, but not identical, to the same forces influencing the prices of the holdings of the Fund trading individually or in the aggregate at any point in time. However, given that shares can only be purchased and redeemed in Creation Units, and only to and from broker-dealers and large institutional investors that have entered into participation agreements (unlike shares of closed-end funds, which frequently trade at appreciable discounts from, and sometimes at premiums to, their net asset value), the Fund’s investment advisor believes that large discounts or premiums to the net asset value of shares should not be sustained. During stressed market conditions, the market for the Fund’s shares may become less liquid in response to deteriorating liquidity in the market for the Fund’s underlying portfolio holdings, which could in turn lead to differences between the market price of the Fund’s shares and their net asset value and the bid/ask spread on the Fund’s shares may widen.
First Trust WCM Developing World Equity ETF | Significant Exposure Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock SIGNIFICANT EXPOSURE RISK. To the extent that the Fund invests a significant percentage of its assets in a single asset class or industry or sector, an adverse economic, business or political development may affect the value of the Fund’s investments more than if the Fund were more broadly diversified. A significant exposure makes the Fund more susceptible to any single occurrence and may subject the Fund to greater market risk than a fund that is more broadly diversified.
First Trust WCM Developing World Equity ETF | Smaller Companies Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock SMALLER COMPANIES RISK. Small and/or mid capitalization companies may be more vulnerable to adverse general market or economic developments, and their securities may be less liquid and may experience greater price volatility than larger, more established companies as a result of several factors, including limited trading volumes, fewer products or financial resources, management inexperience and less publicly available information. Accordingly, such companies are generally subject to greater market risk than larger, more established companies.
First Trust WCM Developing World Equity ETF | Trading Issues Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock TRADING ISSUES RISK. Trading in Fund shares on the Exchange may be halted due to market conditions or for reasons that, in the view of the Exchange, make trading in shares inadvisable. In addition, trading in Fund shares on the Exchange is subject to trading halts caused by extraordinary market volatility pursuant to the Exchange’s “circuit breaker” rules. There can be no assurance that the requirements of the Exchange necessary to maintain the listing of the Fund will continue to be met or will remain unchanged. The Fund may have difficulty maintaining its listing on the Exchange in the event the Fund’s assets are small, the Fund does not have enough shareholders, or if the Fund is unable to proceed with creation and/or redemption orders.
First Trust WCM Developing World Equity ETF | Valuation Risk [Member]  
Risk Return Abstract rr_RiskReturnAbstract  
Risk [Text Block] rr_RiskTextBlock VALUATION RISK. The Fund may hold securities or other assets that may be valued on the basis of factors other than market quotations. This may occur because the asset or security does not trade on a centralized exchange, or in times of market turmoil or reduced liquidity. There are multiple methods that can be used to value a portfolio holding when market quotations are not readily available. Fund investments that trade on non-U.S. exchanges that close prior to the close of the NYSE may be fair valued using a systematic fair valuation model. If these foreign investments meet certain criteria in relation to the valuation model, their valuation is systematically adjusted to reflect the impact of movement in the U.S. market after the close of certain foreign markets. The value established for any portfolio holding at a point in time might differ from what would be produced using a different methodology or if it had been priced using market quotations. In addition, there is no assurance that the Fund could sell or close out a portfolio position for the value established for it at any time, and it is possible that the Fund would incur a loss because a portfolio position is sold or closed out at a discount to the valuation established by the Fund at that time. The Fund’s ability to value investments may be impacted by technological issues or errors by pricing services or other third-party service providers.
First Trust WCM Developing World Equity ETF | First Trust WCM Developing World Equity ETF  
Risk Return Abstract rr_RiskReturnAbstract  
Maximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price)[ctag:span_t-rule1] rr_MaximumSalesChargeImposedOnPurchasesOverOfferingPrice none
Management Fees[ctag:span_t-indent1] rr_ManagementFeesOverAssets 0.95%
Distribution and Service (12b-1) Fees[ctag:span_t-indent1] rr_DistributionAndService12b1FeesOverAssets none
Other Expenses[ctag:span_t-indent1-rule] rr_OtherExpensesOverAssets none
Total Annual Fund Operating Expenses[ctag:span_t-indent1-rule3] rr_ExpensesOverAssets 0.95%
1 Year rr_ExpenseExampleNoRedemptionYear01 $ 97
3 Years rr_ExpenseExampleNoRedemptionYear03 303
5 Years rr_ExpenseExampleNoRedemptionYear05 525
10 Years rr_ExpenseExampleNoRedemptionYear10 $ 1,166
2021 rr_AnnualReturn2021 (1.92%)
2022 rr_AnnualReturn2022 (13.61%)
2023 rr_AnnualReturn2023 6.86%
2024 rr_AnnualReturn2024 0.45%
Highest Quarterly Return, Label rr_HighestQuarterlyReturnLabel <span style="font-family:Arial;font-size:9.00pt;margin-left:0.0pt;">Best Quarter</span>
Highest Quarterly Return, Date rr_BarChartHighestQuarterlyReturnDate Dec. 31, 2022
Highest Quarterly Return rr_BarChartHighestQuarterlyReturn 15.29%
Lowest Quarterly Return, Label rr_LowestQuarterlyReturnLabel <span style="font-family:Arial;font-size:9.00pt;margin-left:0.0pt;">Worst Quarter</span>
Lowest Quarterly Return, Date rr_BarChartLowestQuarterlyReturnDate Jun. 30, 2022
Lowest Quarterly Return rr_BarChartLowestQuarterlyReturn (13.48%)
1 Year rr_AverageAnnualReturnYear01 0.45%
Since Inception rr_AverageAnnualReturnSinceInception 7.50%
Inception Date rr_AverageAnnualReturnInceptionDate Mar. 31, 2020
First Trust WCM Developing World Equity ETF | After tax on distributions | First Trust WCM Developing World Equity ETF  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 0.22%
Since Inception rr_AverageAnnualReturnSinceInception 6.81%
First Trust WCM Developing World Equity ETF | After tax on distributions and sale of fund shares | First Trust WCM Developing World Equity ETF  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 0.26%
Since Inception rr_AverageAnnualReturnSinceInception 5.72%
First Trust WCM Developing World Equity ETF | MSCI Emerging Markets Index (reflects no deduction for fees, expenses or taxes)  
Risk Return Abstract rr_RiskReturnAbstract  
1 Year rr_AverageAnnualReturnYear01 7.50%
Since Inception rr_AverageAnnualReturnSinceInception 7.72%