Gabelli Global Technology Leaders ETF Equity Risk [Member] Foreign Securities Risk [Member] Concentration Risk [Member] Early Closetrading Halt Risk [Member] Authorized Participant Concentration Risk [Member] Market Trading Risk [Member] Risk Of Investing In Japan [Member] Risk Of Investing In Europe [Member] Risk Of Investing In United Kingdom [Member] Technology Sector Risk [Member] American Depositary Receipts A D Rs Risk [Member] Geopolitical Risk [Member] Issuer Risk [Member] Large Capitalization Companies Risk [Member] Small And Midcapitalization Companies Risk [Member] Inflation Risk [Member] Management Risk [Member] Market Risk [Member] Nondiversification Risk [Member] Large Shareholder Risk [Member] Absence Of Active Market [Member] Trading Issues Risk [Member] Gabelli Global Technology Leaders ETF S&P 500 Index (reflects no deduction for fees, expenses or taxes) Gabelli Global Technology Leaders ETF [Default Label]