Themes Optical ETF Concentration Risk [Member] Calculation Methodology Risk [Member] Calculation Methodology Risk Related To Certain Chinese Companies [Member] Counterpartycollateral Risk [Member] Custody Risk [Member] Cybersecurity Risk [Member] Depositary Receipts Risk [Member] Derivatives Risk [Member] Equity Market Risk [Member] Etf Risks [Member] Foreign Currency Risk [Member] Foreign Securities Risk [Member] Geographic Risk [Member] Government Regulation Of Derivatives Risk [Member] International Closed Market Trading Risk [Member] Largecapitalization Investing Risk [Member] Line Of Business Risk [Member] Liquidity Risk [Member] Midcapitalization Companies Risk [Member] Natural Language Processing N L P Model Risk [Member] New Fund Risk [Member] Nondiversification Risk [Member] Operational Risk [Member] Passive Investment Risk [Member] Sector Risk [Member] Securities Lending Risk [Member] Smallcapitalization Investing Risk [Member] Thematic Investing Risk [Member] Tracking Risk [Member] Valuation Risk [Member] Themes Optical ETF Themes Optical ETF [Default Label]