First Trust WCM International Equity ETF Investment Strategy - First Trust WCM International Equity ETF	Dec. 31, 2025
Prospectus [Line Items]
Strategy [Heading]	<span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Principal Investment Strategies</span>
Strategy Narrative [Text Block]	Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of non-U.S. domiciled companies / companies not located in the U.S. 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 focuses on companies that the Fund’s investment sub-advisor, WCM Investment Management, LLC (the "Sub-Advisor") believes to be undervalued because their businesses are out of favor and/or their stocks are undervalued in comparison to their intrinsic values, their peers, or their prospects for growth. 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”). The Fund may invest in equity securities or depositary receipts of companies located in developed countries and in emerging market and frontier market countries. Emerging market and frontier market countries are those countries with low- to middle-income economies as classified by the World Bank, or included in any of the Morgan Stanley Capital International (“MSCI”) emerging markets or frontier markets indices. The Fund’s investment 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 domiciled in one or a few countries or regions. The Sub-Advisor’s investment process begins with a bottom-up, fundamental research approach to identify companies with comparatively low valuations compared to other companies of similar market capitalization, sector, and/or industry, based on factors such as the price-to-earnings ratio, price-to-book ratio, price-to-cash flow ratio, dividend yield, net working capital, and earnings estimate revisions. The Fund’s Sub-Advisor believes that investment in a company with relatively low valuations may afford capital protection from permanent loss and may result in substantial appreciation if the market recognizes the company’s intrinsic value. The Sub-Advisor’s investment process seeks companies that are industry leaders with expanding competitive advantages, strong balance sheets, and attractive valuations. In selecting securities, the Fund’s Sub-Advisor also considers other factors including, among others, potential political, monetary policy, and regulatory impacts. As of March 31, 2026, the Fund had significant investments in issuers located in the United Kingdom, European 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, 2026. 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. In order to gain exposure to certain Chinese companies that are unavailable to direct investment by foreign investors, the Fund invests significantly in non-Chinese shell companies that have created structures known as variable interest entities (“VIEs”) in order to gain exposure to such Chinese companies. 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.
Strategy Portfolio Concentration [Text]	<span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">As of March 31, 2026, the Fund had significant investments in issuers located in the United Kingdom, European issuers and Asian issuers, although this may change from time to time.</span>

First Trust WCM International Equity ETF Investment Strategy - First Trust WCM International Equity ETF

Dec. 31, 2025

<span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Principal Investment Strategies</span>

Under normal circumstances, the Fund invests at least 80% of its net assets (plus any borrowings for investment purposes) in equity securities of non-U.S. domiciled companies / companies not located in the U.S. 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 focuses on companies that the Fund’s investment sub-advisor, WCM Investment Management, LLC (the "Sub-Advisor") believes to be undervalued because their businesses are out of favor and/or their stocks are undervalued in comparison to their intrinsic values, their peers, or their prospects for growth. 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”). The Fund may invest in equity securities or depositary receipts of companies located in developed countries and in emerging market and frontier market countries. Emerging market and frontier market countries are those countries with low- to middle-income economies as classified by the World Bank, or included in any of the Morgan Stanley Capital International (“MSCI”) emerging markets or frontier markets indices. The Fund’s investment 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 domiciled in one or a few countries or regions. The Sub-Advisor’s investment process begins with a bottom-up, fundamental research approach to identify companies with comparatively low valuations compared to other companies of similar market capitalization, sector, and/or industry, based on factors such as the price-to-earnings ratio, price-to-book ratio, price-to-cash flow ratio, dividend yield, net working capital, and earnings estimate revisions. The Fund’s Sub-Advisor believes that investment in a company with relatively low valuations may afford capital protection from permanent loss and may result in substantial appreciation if the market recognizes the company’s intrinsic value. The Sub-Advisor’s investment process seeks companies that are industry leaders with expanding competitive advantages, strong balance sheets, and attractive valuations. In selecting securities, the Fund’s Sub-Advisor also considers other factors including, among others, potential political, monetary policy, and regulatory impacts. As of March 31, 2026, the Fund had significant investments in issuers located in the United Kingdom, European 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, 2026. 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. In order to gain exposure to certain Chinese companies that are unavailable to direct investment by foreign investors, the Fund invests significantly in non-Chinese shell companies that have created structures known as variable interest entities (“VIEs”) in order to gain exposure to such Chinese companies. 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.

Strategy Portfolio Concentration [Text]

<span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">As of March 31, 2026, the Fund had significant investments in issuers located in the United Kingdom, European issuers and Asian issuers, although this may change from time to time.</span>