v3.25.2
First Trust Nasdaq Bank ETF Average Annual Total Returns
12 Months Ended 60 Months Ended 99 Months Ended
Mar. 31, 2025
Dec. 31, 2024
Dec. 31, 2024
Dec. 31, 2024
Nasdaq US Smart Banks(TM) Index (reflects no deduction for fees, expenses or taxes)[Member]        
Prospectus [Line Items]        
Average Annual Return, Percent   29.77% 6.06% 9.23%
Nasdaq US Benchmark(TM) Index (reflects no deduction for fees, expenses or taxes)[Member]        
Prospectus [Line Items]        
Average Annual Return, Percent   24.48% 14.04% 14.52%
Nasdaq US Benchmark Banks(TM) Index (reflects no deduction for fees, expenses or taxes)[Member]        
Prospectus [Line Items]        
Average Annual Return, Percent   34.65% 7.98% 12.17%
First Trust Nasdaq Bank ETF        
Prospectus [Line Items]        
Average Annual Return, Percent   28.92% 5.37% 8.52%
Performance Inception Date Sep. 20, 2016      
First Trust Nasdaq Bank ETF | After Taxes on Distributions        
Prospectus [Line Items]        
Average Annual Return, Percent   27.65% 4.16% 7.38%
First Trust Nasdaq Bank ETF | After Taxes on Distributions and Sales        
Prospectus [Line Items]        
Average Annual Return, Percent   17.04% 3.54% 6.25%