Risk	3 Months Ended
Sep. 30, 2017
Risks and Uncertainties [Abstract]
Risk	(6) Risk (a) Investment Related Risk The NAV of the Fund’s shares relates directly to the value of the U.S. treasuries, cash and cash equivalents held by the Fund and the portfolio’s negative effective duration established and maintained through the Fund’s investment in Treasury Instruments. Fluctuations in the prices of these assets could materially adversely affect the value and performance of an investment in the Fund’s shares. Past performance is not necessarily indicative of future results; all or substantially all of an investment in the Fund could be lost. Investments in debt securities typically decrease in value when interest rates rise, however, the Fund attempts to maintain a portfolio with a negative effective duration and therefore anticipates that an increase in interest rates may increase the Fund’s value, and a decrease in rates may lower the Fund’s value. The NAV of the Fund’s shares relates directly to the value of U.S. Treasuries and Treasury Instruments held by the Fund which are materially impacted by interest rate movements. The magnitude of the impact on value from a change in interest rates is often greater for longer-term fixed income than shorter-term securities. Interest rates have been near historic lows since the market events of 2008 and may remain low. Interest rate movements are heavily influenced by the action of the Board of Governors of the Federal Reserve System and other central banks. Their actions are based on judgments and policies which involve numerous political and economic factors which are unpredictable. Recent interest rate and monetary policies have been unprecedented and may continue to be so. The Fund attempts to track a portfolio benchmark. The performance of the Fund may not closely track the performance of the benchmark portfolio for a variety of reasons. For example, the Fund incurs operating expenses and portfolio transaction costs not incurred by the benchmark. The Fund is also required to manage cash flows and may experience operational inefficiencies the benchmark does not. In addition, the Fund may not be fully invested in the contents of its benchmark at all times or may hold securities not included in its benchmark. The Fund invests in Treasury Instruments and U.S. treasuries with exposure to different maturity dates. Generally, the Fund’s exposure to securities with maturities of 2 and 5 years will be greater than its exposure to securities with maturities of 10 years. Interest rates do not change uniformly for U.S. Treasuries of different maturities and therefore if interest rates rise, the investment performance of the Fund will be impacted by the Fund’s current maturity exposure which may be different from the expectations of the Sponsor and investors in the Fund. At any time, the Fund’s maturity exposure may not be optimal with respect to a movement in interest rates which would negatively impact performance. (b) Liquidity Risk In certain circumstances, such as the disruption of the orderly markets for the futures contracts or Financial Instruments in which the Fund invests, the Fund might not be able to dispose of certain holdings quickly or at prices that represent what the market value may have been in an orderly market. Futures and option positions cannot always be liquidated at the desired price. It is difficult to execute a trade at a specific price when there is a relatively small volume of buy and sell orders in a market. A market disruption can also make it difficult to liquidate a position. The large size of the positions that the Fund may acquire increases the risk of illiquidity both by making its positions more difficult to liquidate and by potentially increasing losses while trying to do so. Such a situation may prevent the Fund from limiting losses, realizing gains or achieving a high correlation with the Benchmark Portfolio.

Risk

3 Months Ended

Sep. 30, 2017

(6) Risk

(a) Investment Related Risk

The NAV of the Fund’s shares relates directly to the value of the U.S. treasuries, cash and cash equivalents held by the Fund and the portfolio’s negative effective duration established and maintained through the Fund’s investment in Treasury Instruments. Fluctuations in the prices of these assets could materially adversely affect the value and performance of an investment in the Fund’s shares. Past performance is not necessarily indicative of future results; all or substantially all of an investment in the Fund could be lost.

Investments in debt securities typically decrease in value when interest rates rise, however, the Fund attempts to maintain a portfolio with a negative effective duration and therefore anticipates that an increase in interest rates may increase the Fund’s value, and a decrease in rates may lower the Fund’s value. The NAV of the Fund’s shares relates directly to the value of U.S. Treasuries and Treasury Instruments held by the Fund which are materially impacted by interest rate movements. The magnitude of the impact on value from a change in interest rates is often greater for longer-term fixed income than shorter-term securities. Interest rates have been near historic lows since the market events of 2008 and may remain low.

Interest rate movements are heavily influenced by the action of the Board of Governors of the Federal Reserve System and other central banks. Their actions are based on judgments and policies which involve numerous political and economic factors which are unpredictable. Recent interest rate and monetary policies have been unprecedented and may continue to be so.

The Fund attempts to track a portfolio benchmark. The performance of the Fund may not closely track the performance of the benchmark portfolio for a variety of reasons. For example, the Fund incurs operating expenses and portfolio transaction costs not incurred by the benchmark. The Fund is also required to manage cash flows and may experience operational inefficiencies the benchmark does not. In addition, the Fund may not be fully invested in the contents of its benchmark at all times or may hold securities not included in its benchmark.

The Fund invests in Treasury Instruments and U.S. treasuries with exposure to different maturity dates. Generally, the Fund’s exposure to securities with maturities of 2 and 5 years will be greater than its exposure to securities with maturities of 10 years. Interest rates do not change uniformly for U.S. Treasuries of different maturities and therefore if interest rates rise, the investment performance of the Fund will be impacted by the Fund’s current maturity exposure which may be different from the expectations of the Sponsor and investors in the Fund. At any time, the Fund’s maturity exposure may not be optimal with respect to a movement in interest rates which would negatively impact performance.

(b) Liquidity Risk

In certain circumstances, such as the disruption of the orderly markets for the futures contracts or Financial Instruments in which the Fund invests, the Fund might not be able to dispose of certain holdings quickly or at prices that represent what the market value may have been in an orderly market. Futures and option positions cannot always be liquidated at the desired price. It is difficult to execute a trade at a specific price when there is a relatively small volume of buy and sell orders in a market. A market disruption can also make it difficult to liquidate a position. The large size of the positions that the Fund may acquire increases the risk of illiquidity both by making its positions more difficult to liquidate and by potentially increasing losses while trying to do so. Such a situation may prevent the Fund from limiting losses, realizing gains or achieving a high correlation with the Benchmark Portfolio.