First Trust Alerian Disruptive Technology Real Estate ETF Performance Management - First Trust Alerian Disruptive Technology Real Estate ETF	Sep. 30, 2025
Prospectus [Line Items]
Bar Chart and Performance Table [Heading]	<span style="color:#000000;font-family:Arial;font-size:9.90pt;font-weight:bold;">Annual Total Return</span>
Performance Narrative [Text Block]	The bar chart and table below illustrate the annual calendar year returns of the Fund based on net asset value as well as the average annual Fund and Index 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 from year-to-year and by showing how the Fund’s average annual total returns based on net asset value compared to those of the Index, the prior Index, three market indices that the Advisor believes reflect the market sectors in which the Fund invests and a broad-based securities market index. The Fund’s performance information is accessible on the Fund’s website at http://www.ftportfolios.com.On September 30, 2022, the Fund’s underlying index changed from the FTSE EPRA/NAREIT Developed Index to the Alerian Disruptive Technology Real Estate Index. Therefore, the Fund’s performance and historical returns shown below are not necessarily indicative of the performance that the Fund, based on the Index, would have generated. Returns for an index are only disclosed for those periods in which the index was in existence for the whole period.
Performance Past Does Not Indicate Future [Text]	<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>
Performance Information Illustrates Variability of Returns [Text]	<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 based on net asset value as well as the average annual Fund and Index 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 from year-to-year and by showing how the Fund’s average annual total returns based on net asset value compared to those of the Index, the prior Index, </span><span style="font-family:Arial;font-size:9.00pt;">three market indices that the Advisor believes reflect </span><span style="font-family:Arial;font-size:9.00pt;margin-left:0%;">the market sectors in which the Fund invests</span><span style="font-family:Arial;font-size:9.00pt;"> and a broad-based securities market index. </span>
Bar Chart [Heading]	<span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">First Trust Alerian Disruptive Technology Real Estate 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]	During the periods shown in the chart above:ReturnPeriod EndedBest Quarter15.57%September 30, 2024Worst Quarter-28.48%March 31, 2020
Performance Table Heading	<span style="font-family:Arial;font-size:9.90pt;font-weight:bold;">Average Annual Total Returns for the Periods Ended December 31, 2025</span>
Performance Table Market Index Changed	<span style="color:#000000;font-family:Arial;font-size:8.10pt;font-style:italic;">On September 30, 2022, the Fund’s underlying index changed from the FTSE EPRA/NAREIT Developed Index to the Alerian Disruptive Technology Real Estate Index. Therefore, the Fund’s performance and historical returns shown for periods prior to this date are not necessarily indicative of the performance the Fund, based on this current index, would have generated.</span>
Performance Table Uses Highest Federal Rate	<span style="color:#000000;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	<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	<span style="color:#000000;font-family:Arial;font-size:9.00pt;">Returns after taxes on distributions reflect the taxed return on the payment of dividends </span><span style="color:#000000;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 an index do not include expenses, which are </span><span style="color:#000000;font-family:Arial;font-size:9.00pt;">deducted from Fund returns, or taxes.</span>
Performance Availability Website Address [Text]	<span style="font-family:Arial;font-size:9.00pt;">http://www.ftportfolios.com</span>
First Trust Alerian Disruptive Technology Real Estate ETF
Prospectus [Line Items]
Highest Quarterly Return, Label [Optional Text]	<span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;">Best Quarter</span>
Highest Quarterly Return	15.57%
Highest Quarterly Return, Date	Sep. 30, 2024
Lowest Quarterly Return, Label [Optional Text]	<span style="color:#000000;font-family:Arial;font-size:9.00pt;margin-left:0.0pt;">Worst Quarter</span>
Lowest Quarterly Return	(28.48%)
Lowest Quarterly Return, Date	Mar. 31, 2020