F/m Accumulator Ultrashort U.S. Treasury Fund F/m Accumulator Ultrashort U.S. Treasury Fund Shares Active Management Risk Affiliated Fund Risk Asset Class Risk Call Risk Cash or Cash Equivalents Risk Concentration Risk Credit Risk [Member] Cyber Security Risk Derivatives Risk Duration Risk ETF Risk Fixed-Income Market Risk Fixed-Income Securities Risk Fund of Funds Risk Futures Risk High Portfolio Turnover Risk Income Risk Inflation Risk Interest Rate Risk [Member] Issuer Risk Liquidity Risk Management Risk Market Risk Market Price Risk Market Trading Risk New Fund Risk Operational Risk Options Risk Premium/Discount Risk Prepayment and Extension Risk Pricing Risk Rating Agencies Risk Reinvestment Risk Reverse Repurchase Agreements Risk Risk of Investing in the U.S. Sector Risk Securities Lending Risk Tax Risk Underlying Funds Risk U.S. Government Obligations Risk U.S. Treasury and Agency Market Risk Valuation Risk F/m Accumulator Intermediate U.S. Treasury Fund F/m Accumulator Intermediate U.S. Treasury Fund Shares F/m Accumulator Long-Term U.S. Treasury Fund F/m Accumulator Long-Term U.S. Treasury Fund Shares F/m Accumulator TIPS Fund F/m Accumulator TIPS Fund Shares Inflation-Indexed Bonds Risk Inflation-Linked Securities Risk