Defiance Small Modular Reactor ETF Equity Market Risk [Member] Focused Portfolio Risk [Member] Index Strategy Risk [Member] Data Risk [Member] Passive Investment Risk [Member] Tracking Error Risk [Member] Concentration Risk [Member] Small Modular Reactor (SMR) Companies Risks [Member] Nuclear Industry Companies Risks [Member] Uranium Investment Risks [Member] Management Risk [Member] Risks Related to Changes in Government Policies and Institutions [Member] Foreign Securities Risk [Member] Derivatives Risk [Member] Options Contracts [Member]  Swap Agreements [Member] Equity Total Return Swaps [Member] Counterparty Risk [Member] ETF Risks [Member] Authorized Participants, Market Makers, and Liquidity Providers Concentration Risk [Member] Cash Redemption Risk [Member] Costs of Buying or Selling Shares [Member] Shares May Trade at Prices Other Than NAV [Member] Trading [Member] Liquidity Risk [Member] Economic and Market Risk [Member] Liquidity Risks [Member] Money Market Instrument Risk [Member] Market Capitalization Risk [Member] New Fund Risk [Member] Operational Risk [Member] Tax Risk [Member] Underlying Index Risk [Member] Defiance Small Modular Reactor ETF [Member] Developed Markets Risk [Member] Emerging Markets Risk [Member] Currency Risk [Member] Depositary Receipt Risk [Member] Large-Capitalization Investing [Member] Mid-Capitalization Investing [Member] Small-Capitalization Investing [Member] Defiance Small Modular Reactor ETF. Defiance Small Modular Reactor ETF. Underlying Index Risk. Tax Risk. Operational Risk. New Fund Risk. Large-Capitalization Investing. Market Capitalization Risk. Money Market Instrument Risk. Liquidity Risks. Economic and Market Risk. Liquidity Risk. Trading. Shares May Trade at Prices Other Than NAV. Costs of Buying or Selling Shares. Cash Redemption Risk. Authorized Participants, Market Makers, and Liquidity Providers Concentration Risk. ETF Risks. Counterparty Risk. Equity Total Return Swaps. Swap Agreements. Options Contracts.  Derivatives Risk. Developed Markets Risk. Foreign Securities Risk. Risks Related to Changes in Government Policies and Institutions. Management Risk. Uranium Investment Risks. Nuclear Industry Companies Risks. Small Modular Reactor (SMR) Companies Risks. Concentration Risk. Tracking Error Risk. Passive Investment Risk. Data Risk. Index Strategy Risk. Focused Portfolio Risk. Equity Market Risk. Emerging Markets Risk. Currency Risk. Depositary Receipt Risk. Mid-Capitalization Investing. Small-Capitalization Investing.