v3.26.1
Average Annual Total Returns
12 Months Ended 19 Months Ended
Aug. 31, 2025
Dec. 31, 2024
Dec. 31, 2024
Russell 2000® Index (reflects no deduction for fees, expenses or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent   11.54% 16.91%
Russell 3000® Index (reflects no deduction for fees, expenses or taxes)[Member]      
Prospectus [Line Items]      
Average Annual Return, Percent   23.81% 24.72%
FT Vest U.S. Small Cap Moderate Buffer ETF - May      
Prospectus [Line Items]      
Average Annual Return, Percent   12.61% 13.98%
Performance Inception Date May 19, 2023    
FT Vest U.S. Small Cap Moderate Buffer ETF - May | After Taxes on Distributions      
Prospectus [Line Items]      
Average Annual Return, Percent   12.61% 13.98%
FT Vest U.S. Small Cap Moderate Buffer ETF - May | After Taxes on Distributions and Sales      
Prospectus [Line Items]      
Average Annual Return, Percent   7.47% 10.76%