v3.26.1
First Trust NYSE Arca Biotechnology Index Fund Expense Example, No Redemption - First Trust NYSE Arca Biotechnology Index Fund - First Trust NYSE Arca Biotechnology Index Fund
Dec. 31, 2025
USD ($)
Prospectus [Line Items]  
Expense Example, No Redemption, 1 Year $ 56
Expense Example, No Redemption, 3 Years 176
Expense Example, No Redemption, 5 Years 307
Expense Example, No Redemption, 10 Years $ 689