v3.26.1
Average Annual Total Returns
 12 Months Ended 60 Months Ended 120 Months Ended 259 Months Ended
May 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Dec. 31, 2025
Bloomberg US Aggregate Bond Index (reflects no deduction for fees, expenses or taxes)[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent   7.30% (0.36%) 2.01% 3.36%
Morningstar® LSTA® US Leveraged Loan Index[Member]          
Prospectus [Line Items]          
Average Annual Return, Percent   5.90% 6.42% 5.83% 5.06%
First Trust Flexible Income ETF          
Prospectus [Line Items]          
Average Annual Return, Percent [1]   6.87% 6.04% 6.06% 4.77%
Performance Inception Date [1] May 25, 2004        
First Trust Flexible Income ETF | After Taxes on Distributions          
Prospectus [Line Items]          
Average Annual Return, Percent   1.96% 1.76% 2.38% 1.73%
First Trust Flexible Income ETF | After Taxes on Distributions and Sales          
Prospectus [Line Items]          
Average Annual Return, Percent   3.83% 2.62% 2.90% 2.20%
[1] Total return is based on the combination of reinvested dividend, capital gain, and return of capital distributions, at prices obtained by the Predecessor Fund’s Dividend Reinvestment Plan and changes in NAV per share. Total returns are not annualized for periods of less than one year. Past performance is not indicative of future results.