Investment Risks |
Apr. 01, 2026 |
|---|---|
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | ContractsForDifferenceCfdRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Contracts for Difference (CFD) Risk. The fund may invest in Contracts for Difference (CFD), an OTC derivative total return swap transaction where the underlying reference asset will be a single equity stock or financial index. The fund could experience losses if the underlying asset or reference does not perform as anticipated. The fund may only close out a swap with its particular counterparty and may only transfer a position with the consent of that counterparty. Short CFD transactions have the potential for unlimited losses, regardless of the size of the initial investment. CFD agreements may be used to obtain exposure to a security or market without owning or taking physical custody of such security or investing directly in such market. CFD exposure may effectively add leverage to the fund's portfolio because, in addition to its total net assets, the fund would be subject to investment exposure on the notional amount of the swap. CFDs are subject to the risk that a counterparty will default on its payment obligations to the fund. CFD agreements also bear the risk that the fund will not be able to meet its obligation to the counterparty. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | ForeignCurrencyTransactionsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign Currency Transactions. The fund may enter into forward foreign currency exchange contracts for hedging purposes. A forward foreign currency exchange contract, which involves an obligation to purchase or sell a specific currency at a future date at a price set at the time of the contract, reduces a fund's exposure to changes in the value of the currency it will deliver and increases its exposure to changes in the value of the currency it will receive for the duration of the contract. Foreign exchange rates can be extremely volatile and the degree of volatility of the market or in the direction of the market from that anticipated by the Adviser may result in losses to the fund. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | ShortSalesAndLeverageRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Short Sales and Leverage Risk. Short sales pose more risk than long positions. Because a short position loses value as the security's price increases, the loss on a short sale is theoretically unlimited. Regulatory bans on certain short selling activities may prevent a fund from fully implementing its strategy. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. The fund's use of derivative instruments may result in losses. The value of derivative instruments may pose risks in addition to and greater than those associated with investing directly in securities, currencies or other instruments and may be illiquid or less liquid, volatile, difficult to price and leveraged so that small changes in the value of underlying instruments may produce disproportionate losses to the fund. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments. Moreover, a relatively small price movement in a derivative contract may result in substantial losses to the fund, exceeding the amount of the margin paid. The use of derivatives can increase the fund's risk exposure to underlying assets and their attendant risks, while also exposing the fund to the risk of mispricing or other improper valuation and the risk that changes in the value of a derivative may not correlate as anticipated with the underlying asset, rate, index or overall securities markets, thereby reducing their effectiveness. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | FuturesContractRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Futures Contract Risk. The fund may invest in bond, currency, equity, index, and interest rate futures contracts. Certain futures contract markets are highly volatile, the use of futures may increase the volatility of the fund's net asset value per share (NAV), and futures contracts may be illiquid or less liquid than the underlying reference. Futures are traded on exchanges that may limit fluctuations in futures contract prices by imposing a maximum permissible daily price movement. The fund may be disadvantaged if it is prohibited from executing a trade outside the daily permissible price movement. Positions in futures contracts may be closed out only on the exchange on which they were entered into or through a linked exchange, and no secondary market exists for such contracts. Futures positions are marked to market each day and variation margin payment must be paid to or by the fund. Because of the low margin deposits normally required in futures trading, it is possible that the fund may employ a high degree of leverage in the portfolio. For certain types of futures contracts, losses are theoretically unlimited. Moreover, futures contracts executed (if any) on foreign exchanges may not provide the same protection as U.S. exchanges. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | USGovernmentObligationsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | GeographicExposureToEuropeMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Geographic Exposure to Europe. Because the fund invests a meaningful portion of its assets in Europe, the fund's performance is expected to be closely tied to social, political, and economic conditions within Europe and to be more volatile than the performance of more geographically diversified funds. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | ForeignAndEmergingMarketsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign and Emerging Markets Risk. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information available to investors. Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties and can be extremely volatile. Foreign exchange rates also can be extremely volatile. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelityEquityMarketNeutralFund-AMCIZPro | Fidelity Equity Market Neutral Fund | SwapsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Swaps Risk. The fund may invest in excess return and total return swaps. Swaps may be difficult to value and may be illiquid. The fund could experience losses if the underlying asset or reference does not perform as anticipated. Certain swaps have the potential for unlimited losses, regardless of the size of the initial investment. |
| FidelityHedgedEquityFund-AMCIZPRO | Fidelity Hedged Equity Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelityHedgedEquityFund-AMCIZPRO | Fidelity Hedged Equity Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelityHedgedEquityFund-AMCIZPRO | Fidelity Hedged Equity Fund | OptionsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Options Risk. The fund may purchase or write (i.e., sell) put and call options. Under certain circumstances, the fund may be required to buy or sell the underlying reference at a disadvantageous price, resulting in a loss. Options may involve economic leverage, which could result in greater volatility in price movement. Certain transaction costs associated with purchasing and writing options may impact the fund's returns. |
| FidelityHedgedEquityFund-AMCIZPRO | Fidelity Hedged Equity Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. |
| FidelityHedgedEquityFund-AMCIZPRO | Fidelity Hedged Equity Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelityHedgedEquityFund-AMCIZPRO | Fidelity Hedged Equity Fund | HighPortfolioTurnoverMember | |
| Prospectus Line Items | |
| Risk [Text Block] | High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | AssetAllocationRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Asset Allocation Risk. The fund is subject to risks resulting from the Adviser's asset allocation decisions. The selection of underlying funds and the allocation of the fund's assets among various asset classes could cause the fund to lose value or its results to lag relevant benchmarks or other funds with similar objectives. In addition, the fund's active asset allocation strategy may cause the fund to have a risk profile different than that portrayed above from time to time and may increase losses. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | CurrencyExposureMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Currency Exposure. Because the fund is normally exposed to foreign currencies, it could experience losses based solely on the weakness of foreign currencies versus the U.S. dollar and changes in the exchange rates between foreign currencies and the U.S. dollar. Currency risk may be particularly high to the extent that a fund invests in foreign currencies or engages in foreign currency transactions that are economically tied to emerging markets countries. These emerging markets currency transactions may present market, credit, currency, liquidity, legal, political and other risks different from, or greater than, the risks of investing in developed foreign currencies or engaging in foreign currency transactions that are economically tied to developed foreign countries. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | SubsidiaryRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Subsidiary Risk. Investment in Fidelity Risk Parity Cayman Ltd., an unregistered subsidiary, is not subject to the investor protections of the Investment Company Act of 1940 (1940 Act) and is subject to the risks associated with investing in derivatives and commodity-linked investing in general. Changes in tax and other laws could negatively affect investments in the subsidiary. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | InterestRateChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | QuantitativeInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Quantitative Investing. Securities selected using quantitative analysis can perform differently from the market as a whole as a result of the factors used in the analysis, the weight placed on each factor, and changes in the factors' historical trends. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | CommodityLinkedInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Commodity-Linked Investing. The value of commodities and commodity-linked investments may be affected by the performance of the overall commodities markets as well as weather, political, tax, and other regulatory and market developments. Commodity-linked investments may be more volatile and less liquid than the underlying commodity, instruments, or measures. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | PrepaymentMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | USGovernmentObligationsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | ForeignAndEmergingMarketsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign and Emerging Markets Risk. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information available to investors. Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties and can be extremely volatile. Foreign exchange rates also can be extremely volatile. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | LeverageRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. The fund's use of futures, forwards, options, swaps, and other derivative instruments may result in losses. The value of these derivative instruments may pose risks in addition to and greater than those associated with investing directly in securities, currencies or other instruments and may be illiquid or less liquid, volatile, difficult to price and leveraged so that small changes in the value of underlying instruments may produce disproportionate losses to the fund. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments. Moreover, a relatively small price movement in a derivative contract may result in substantial losses to the fund, exceeding the amount of the margin paid. The use of derivatives can increase the fund's risk exposure to underlying assets and their attendant risks, while also exposing the fund to the risk of mispricing or other improper valuation and the risk that changes in the value of a derivative may not correlate as anticipated with the underlying asset, rate, index or overall securities markets, thereby reducing their effectiveness. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | InvestingInOtherFundsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Investing in Other Funds. Regulatory restrictions may limit the amount that one fund can invest in another, which means that the fund's manager may not be able to invest as much as it wants to in some other funds. The fund bears all risks of investment strategies employed by the underlying funds, including the risk that the underlying funds will not meet their investment objectives. Underlying funds that are passively managed attempt to track the performance of an unmanaged index of securities and as such their performance could be lower than actively managed funds, which may shift their portfolio assets to take advantage of market opportunities or lessen the impact of a market decline. In addition, errors in the construction of the index tracked by an underlying passively managed fund may have an adverse impact on the performance of such underlying fund. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Changes in the financial condition of an issuer or counterparty (e.g., broker-dealer or other borrower in a securities lending transaction) can increase the risk of default by an issuer or counterparty, which can affect a security's or instrument's value or result in delays in recovering securities and/or capital from a counterparty. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | CommodityFuturesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Commodity Futures. Investments in commodity futures contracts are also subject to the risk of the failure of any of the exchanges on which the fund's positions trade or of its clearinghouses or counterparties. In addition, certain commodity exchanges limit fluctuations in certain futures contract prices during a single day by regulations referred to as "daily price fluctuation limits" or "daily limits." Under such daily limits, during a single trading day no trades may be executed at prices beyond the daily limit. If triggered, these limits could prevent the fund from liquidating unfavorable positions and subject the fund to losses or prevent it from entering into desired trades during the particular trading day. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | CorrelationRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Correlation Risk. The fund's investment strategy seeks to balance risk across multiple asset classes and, within each asset class, across different countries and investments. To the extent the asset classes or the selected countries and investments become correlated in a way not anticipated by the Adviser, the fund's risk allocation process may result in magnified risks and loss instead of reducing the risk of loss. |
| FidelityMacroOpportunitiesRiskParityFunds-RetailComboPRO | Fidelity Risk Parity Fund | InvestingInEtfsAndEtnsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Investing in ETFs and ETNs. ETFs and ETNs may trade in the secondary market at prices below the value of their underlying portfolios and may not be liquid. ETFs that track an index are subject to tracking error and may be unable to sell poorly performing assets that are included in their index or other benchmark. ETNs are subject to the risks associated with debt securities, including counterparty risk of the issuer. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | AssetAllocationRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Asset Allocation Risk. The fund is subject to risks resulting from the Adviser's asset allocation decisions. The selection of underlying funds and the allocation of the fund's assets among various asset classes could cause the fund to lose value or its results to lag relevant benchmarks or other funds with similar objectives. In addition, the fund's active asset allocation strategy may cause the fund to have a risk profile different than that portrayed above from time to time and may increase losses. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | CurrencyExposureMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Currency Exposure. Because the fund is normally exposed to foreign currencies, it could experience losses based solely on the weakness of foreign currencies versus the U.S. dollar and changes in the exchange rates between foreign currencies and the U.S. dollar. Currency risk may be particularly high to the extent that a fund invests in foreign currencies or engages in foreign currency transactions that are economically tied to emerging markets countries. These emerging markets currency transactions may present market, credit, currency, liquidity, legal, political and other risks different from, or greater than, the risks of investing in developed foreign currencies or engaging in foreign currency transactions that are economically tied to developed foreign countries. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | SubsidiaryRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Subsidiary Risk. Investment in Fidelity Risk Parity Cayman Ltd., an unregistered subsidiary, is not subject to the investor protections of the Investment Company Act of 1940 (1940 Act) and is subject to the risks associated with investing in derivatives and commodity-linked investing in general. Changes in tax and other laws could negatively affect investments in the subsidiary. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | InterestRateChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | QuantitativeInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Quantitative Investing. Securities selected using quantitative analysis can perform differently from the market as a whole as a result of the factors used in the analysis, the weight placed on each factor, and changes in the factors' historical trends. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | CommodityLinkedInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Commodity-Linked Investing. The value of commodities and commodity-linked investments may be affected by the performance of the overall commodities markets as well as weather, political, tax, and other regulatory and market developments. Commodity-linked investments may be more volatile and less liquid than the underlying commodity, instruments, or measures. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | PrepaymentMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Prepayment. The ability of an issuer of a debt security to repay principal prior to a security's maturity can cause greater price volatility if interest rates change. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | USGovernmentObligationsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | ForeignAndEmergingMarketsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign and Emerging Markets Risk. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information available to investors. Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties and can be extremely volatile. Foreign exchange rates also can be extremely volatile. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | LeverageRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Leverage Risk. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. The fund's use of futures, forwards, options, swaps, and other derivative instruments may result in losses. The value of these derivative instruments may pose risks in addition to and greater than those associated with investing directly in securities, currencies or other instruments and may be illiquid or less liquid, volatile, difficult to price and leveraged so that small changes in the value of underlying instruments may produce disproportionate losses to the fund. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments. Moreover, a relatively small price movement in a derivative contract may result in substantial losses to the fund, exceeding the amount of the margin paid. The use of derivatives can increase the fund's risk exposure to underlying assets and their attendant risks, while also exposing the fund to the risk of mispricing or other improper valuation and the risk that changes in the value of a derivative may not correlate as anticipated with the underlying asset, rate, index or overall securities markets, thereby reducing their effectiveness. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | InvestingInOtherFundsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Investing in Other Funds. Regulatory restrictions may limit the amount that one fund can invest in another, which means that the fund's manager may not be able to invest as much as it wants to in some other funds. The fund bears all risks of investment strategies employed by the underlying funds, including the risk that the underlying funds will not meet their investment objectives. Underlying funds that are passively managed attempt to track the performance of an unmanaged index of securities and as such their performance could be lower than actively managed funds, which may shift their portfolio assets to take advantage of market opportunities or lessen the impact of a market decline. In addition, errors in the construction of the index tracked by an underlying passively managed fund may have an adverse impact on the performance of such underlying fund. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Changes in the financial condition of an issuer or counterparty (e.g., broker-dealer or other borrower in a securities lending transaction) can increase the risk of default by an issuer or counterparty, which can affect a security's or instrument's value or result in delays in recovering securities and/or capital from a counterparty. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | CommodityFuturesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Commodity Futures. Investments in commodity futures contracts are also subject to the risk of the failure of any of the exchanges on which the fund's positions trade or of its clearinghouses or counterparties. In addition, certain commodity exchanges limit fluctuations in certain futures contract prices during a single day by regulations referred to as "daily price fluctuation limits" or "daily limits." Under such daily limits, during a single trading day no trades may be executed at prices beyond the daily limit. If triggered, these limits could prevent the fund from liquidating unfavorable positions and subject the fund to losses or prevent it from entering into desired trades during the particular trading day. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | CorrelationRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Correlation Risk. The fund's investment strategy seeks to balance risk across multiple asset classes and, within each asset class, across different countries and investments. To the extent the asset classes or the selected countries and investments become correlated in a way not anticipated by the Adviser, the fund's risk allocation process may result in magnified risks and loss instead of reducing the risk of loss. |
| FidelityMacroOpportunitiesRiskParityFunds-AMCIZComboPRO | Fidelity Risk Parity Fund | InvestingInEtfsAndEtnsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Investing in ETFs and ETNs. ETFs and ETNs may trade in the secondary market at prices below the value of their underlying portfolios and may not be liquid. ETFs that track an index are subject to tracking error and may be unable to sell poorly performing assets that are included in their index or other benchmark. ETNs are subject to the risks associated with debt securities, including counterparty risk of the issuer. |
| FidelityHedgedEquityFund-RetailPRO | Fidelity Hedged Equity Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelityHedgedEquityFund-RetailPRO | Fidelity Hedged Equity Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelityHedgedEquityFund-RetailPRO | Fidelity Hedged Equity Fund | OptionsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Options Risk. The fund may purchase or write (i.e., sell) put and call options. Under certain circumstances, the fund may be required to buy or sell the underlying reference at a disadvantageous price, resulting in a loss. Options may involve economic leverage, which could result in greater volatility in price movement. Certain transaction costs associated with purchasing and writing options may impact the fund's returns. |
| FidelityHedgedEquityFund-RetailPRO | Fidelity Hedged Equity Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. |
| FidelityHedgedEquityFund-RetailPRO | Fidelity Hedged Equity Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelityHedgedEquityFund-RetailPRO | Fidelity Hedged Equity Fund | HighPortfolioTurnoverMember | |
| Prospectus Line Items | |
| Risk [Text Block] | High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | Risk Nondiversified Status [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | In addition, the fund is classified as non-diversified under the Investment Company Act of 1940 (1940 Act), which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | ConvertibleArbitrageStrategyMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Convertible Arbitrage Strategy. Convertible arbitrage involves purchasing a portfolio of convertible securities, generally convertible bonds, and hedging all or a portion of the equity risk by selling short the underlying common stock. Convertible arbitrage may involve the risk of default in interest or principal payments, which could result in a loss of income to the fund, or a decline in the market value of the securities. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | ShortSalesAndLeverageRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Short Sales and Leverage Risk. Short sales pose more risk than long positions. Because a short position loses value as the security's price increases, the loss on a short sale is theoretically unlimited. Regulatory bans on certain short selling activities may prevent a fund from fully implementing its strategy. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. The fund's use of futures, forwards, options, swaps, and other derivative instruments may result in losses. The value of these derivative instruments may pose risks in addition to and greater than those associated with investing directly in securities, currencies or other instruments and may be illiquid or less liquid, volatile, difficult to price and leveraged so that small changes in the value of underlying instruments may produce disproportionate losses to the fund. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments. Moreover, a relatively small price movement in a derivative contract may result in substantial losses to the fund, exceeding the amount of the margin paid. The use of derivatives can increase the fund's risk exposure to underlying assets and their attendant risks, while also exposing the fund to the risk of mispricing or other improper valuation and the risk that changes in the value of a derivative may not correlate as anticipated with the underlying asset, rate, index or overall securities markets, thereby reducing their effectiveness. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | MidCapInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Mid Cap Investing. The value of securities of medium size, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | USGovernmentObligationsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell. Changes in the financial condition of an issuer or counterparty (e.g., broker-dealer or other borrower in a securities lending transaction) can increase the risk of default by an issuer or counterparty, which can affect a security's or instrument's value or result in delays in recovering securities and/or capital from a counterparty. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | SmallCapInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Small Cap Investing. The value of securities of smaller, less well-known issuers can perform differently from the market as a whole and other types of stocks and can be more volatile than that of larger issuers. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | HighPortfolioTurnoverMember | |
| Prospectus Line Items | |
| Risk [Text Block] | High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance. |
| FidelitySAIConvertibleArbitrageFund-PRO | Fidelity SAI Convertible Arbitrage Fund | ForeignExposureMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | Risk Nondiversified Status [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | In addition, the fund is classified as non-diversified under the Investment Company Act of 1940 (1940 Act), which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | OptionsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Options Risk. The fund may purchase or write (i.e., sell) put and call options. Under certain circumstances, the fund may be required to buy or sell the underlying reference at a disadvantageous price, resulting in a loss. Options may involve economic leverage, which could result in greater volatility in price movement. Certain transaction costs associated with purchasing and writing options may impact the fund's returns. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | InterestRateChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | ShortSalesAndLeverageRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Short Sales and Leverage Risk. Short sales pose more risk than long positions. Because a short position loses value as the security's price increases, the loss on a short sale is theoretically unlimited. Regulatory bans on certain short selling activities may prevent a fund from fully implementing its strategy. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. The fund's use of futures, forwards, options, swaps, and other derivative instruments may result in losses. The value of these derivative instruments may pose risks in addition to and greater than those associated with investing directly in securities, currencies or other instruments and may be illiquid or less liquid, volatile, difficult to price and leveraged so that small changes in the value of underlying instruments may produce disproportionate losses to the fund. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments. Moreover, a relatively small price movement in a derivative contract may result in substantial losses to the fund, exceeding the amount of the margin paid. The use of derivatives can increase the fund's risk exposure to underlying assets and their attendant risks, while also exposing the fund to the risk of mispricing or other improper valuation and the risk that changes in the value of a derivative may not correlate as anticipated with the underlying asset, rate, index or overall securities markets, thereby reducing their effectiveness. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | MergerArbitrageStrategyMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Merger Arbitrage Strategy. Merger arbitrage involves investing in equity securities and equity-related derivative instruments of companies that are or may be involved in a Merger Transaction. If the proposed merger appears likely not to be consummated, is delayed, or fails to be completed, the market price of the target company will usually decline sharply, resulting in loss. Every Merger Transaction is subject to unique risks, including the risk of the Merger Transaction failing as a result of timing risk, regulatory risk, deal financing risk, shareholder approval risk, or for other reasons. In addition, the relationship between the securities in which investment positions are taken may change in an adverse or unanticipated manner. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | USGovernmentObligationsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | SpecialPurposeAcquisitionCompaniesRiskSpacRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Special Purpose Acquisition Companies Risk (SPAC Risk). Because SPACs do not have an operating history or ongoing business other than seeking acquisitions, the value of their securities is particularly dependent on the ability of the SPAC's management to identify and complete a profitable acquisition. Some SPACs may pursue acquisitions only within certain industries or regions, which may increase the volatility of their prices. An investment in a SPAC is subject to a variety of risks, including that (i) an attractive acquisition or merger target may not be identified at all and the SPAC will be required to return any remaining monies to shareholders; (ii) an acquisition or merger once effected may prove unsuccessful and an investment in the SPAC may lose value; (iii) the values of investments in SPACs may be highly volatile and may depreciate significantly over time; (iv) no or only a thinly traded market for shares of or interests in a SPAC may develop, leaving a fund unable to sell its interest in a SPAC or to sell its interest only at a price below what the fund believes is the SPAC interest's intrinsic value; (v) any proposed merger or acquisition may be unable to obtain the requisite approval, if any, of shareholders; (vi) an investment in a SPAC may be diluted by additional later offerings of interests in the SPAC or by other investors exercising existing rights to purchase shares of the SPAC; (vii) the warrants or other rights with respect to the SPAC held by a fund may expire worthless or may be repurchased or retired by the SPAC at an unfavorable price; (viii) a fund may be delayed in receiving any redemption or liquidation proceeds from a SPAC to which it is entitled; and (ix) a significant portion of the monies raised by the SPAC for the purpose of identifying and effecting an acquisition or merger may be expended during the search for a target transaction. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | InvestingInExchangeTradedFundsEtfsAndEtnsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Investing in Exchange Traded Funds (ETFs) and ETNs. ETFs and ETNs may trade in the secondary market at prices below the value of their underlying portfolios and may not be liquid. ETFs that track an index are subject to tracking error and may be unable to sell poorly performing assets that are included in their index or other benchmark. ETNs are subject to the risks associated with debt securities, including counterparty risk of the issuer. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | InvestingInOtherFundsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Investing in Other Funds. Regulatory restrictions may limit the amount that one fund can invest in another, which means that the fund's manager may not be able to invest as much as it wants to in some other funds. The fund bears all risks of investment strategies employed by the underlying funds, including the risk that the underlying funds will not meet their investment objectives. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. A decline in the credit quality of an issuer or a provider of credit support (such as guarantees) or a maturity-shortening structure (such as demand and put features) for a security can cause the price of a security to decrease. Lower-quality debt securities (those of less than investment-grade quality, also referred to as high yield debt securities or junk bonds) and certain types of other securities involve greater risk of default or price changes due to changes in the credit quality of the issuer. The value of lower-quality debt securities and certain types of other securities can be more volatile due to increased sensitivity to adverse issuer, political, regulatory, market, or economic developments and can be difficult to resell. Changes in the financial condition of an issuer or counterparty (e.g., broker-dealer or other borrower in a securities lending transaction) can increase the risk of default by an issuer or counterparty, which can affect a security's or instrument's value or result in delays in recovering securities and/or capital from a counterparty. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | HighPortfolioTurnoverMember | |
| Prospectus Line Items | |
| Risk [Text Block] | High Portfolio Turnover. High portfolio turnover (more than 100%) may result in increased transaction costs and potentially higher capital gains or losses. The effects of higher than normal portfolio turnover may adversely affect the fund's performance. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | ForeignExposureMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign Exposure. Foreign markets can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. |
| FidelitySAIMergerArbitrageFund-PRO | Fidelity SAI Merger Arbitrage Fund | SwapsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Swaps Risk. The fund may invest in excess return and total return swaps. Swaps may be difficult to value and may be illiquid. The fund could experience losses if the underlying asset or reference does not perform as anticipated. Certain swaps have the potential for unlimited losses, regardless of the size of the initial investment. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | Risk Nondiversified Status [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | In addition, the fund is classified as non-diversified under the Investment Company Act of 1940 (1940 Act), which means that it has the ability to invest a greater portion of assets in securities of a smaller number of individual issuers than a diversified fund. As a result, changes in the market value of a single investment could cause greater fluctuations in share price than would occur in a more diversified fund. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | SubsidiaryRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Subsidiary Risk. Investment in Fidelity SAI Managed Futures Fund Cayman Ltd, an unregistered subsidiary, is not subject to the investor protections of the Investment Company Act of 1940 (1940 Act) and is subject to the risks associated with investing in derivatives and commodity-linked investing in general. Changes in tax and other laws could negatively affect investments in the subsidiary. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | InterestRateChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Interest Rate Changes. Interest rate increases can cause the price of a debt security to decrease. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | QuantitativeInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Quantitative Investing. Securities selected using quantitative analysis can perform differently from the market as a whole as a result of the factors used in the analysis, the weight placed on each factor, and changes in the factors' historical trends. In making investment allocation decisions, the Adviser utilizes quantitative models that may be proprietary or developed by third parties. These models are used by the Adviser to determine the fund's target asset allocation. The fund's investment models used in making investment allocation decisions may not adequately consider certain factors, may contain design flaws or faulty assumptions, and may rely on incomplete or inaccurate data, any of which may result in a decline in the value of your investment. There can be no assurance that the models used by the Adviser will remain viable, due to various factors, which may include the quality of the data input into the models and the assumptions underlying such models, which to varying degrees involve the exercise of judgment, as well as the possibility of errors in constructing or using the model. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | ShortSalesAndLeverageRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Short Sales and Leverage Risk. Short sales pose more risk than long positions. Because a short position loses value as the security's price increases, the loss on a short sale is theoretically unlimited. Regulatory bans on certain short selling activities may prevent a fund from fully implementing its strategy. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. The fund's use of futures, forward contracts, options, swaps, and other derivative instruments may result in losses. The value of these derivative instruments may pose risks in addition to and greater than those associated with investing directly in securities, currencies or other instruments and may be illiquid or less liquid, volatile, difficult to price and leveraged so that small changes in the value of underlying instruments may produce disproportionate losses to the fund. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments. Moreover, a relatively small price movement in a derivative contract may result in substantial losses to the fund, exceeding the amount of the margin paid. The use of derivatives can increase the fund's risk exposure to underlying assets and their attendant risks, while also exposing the fund to the risk of mispricing or other improper valuation and the risk that changes in the value of a derivative may not correlate as anticipated with the underlying asset, rate, index or overall securities markets, thereby reducing their effectiveness. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | CommodityLinkedInvestingMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Commodity-Linked Investing. The value of commodities and commodity-linked investments may be affected by the performance of the overall commodities markets as well as weather, political, tax, and other regulatory and market developments. Commodity-linked investments may be more volatile and less liquid than the underlying commodity, instruments, or measures. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | USGovernmentObligationsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | InvestingInOtherFundsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Investing in Other Funds. Regulatory restrictions may limit the amount that one fund can invest in another, which means that the fund's manager may not be able to invest as much as it wants to in some other funds. The fund bears all risks of investment strategies employed by the underlying funds, including the risk that the underlying funds will not meet their investment objectives. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. Changes in the financial condition of an issuer or counterparty (e.g., broker-dealer or other borrower in a securities lending transaction) can increase the risk of default by an issuer or counterparty, which can affect a security's or instrument's value or result in delays in recovering securities and/or capital from a counterparty. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | CommodityFuturesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Commodity Futures. Investments in commodity futures contracts are also subject to the risk of the failure of any of the exchanges on which the fund's positions trade or of its clearinghouses or counterparties. In addition, certain commodity exchanges limit fluctuations in certain futures contract prices during a single day by regulations referred to as "daily price fluctuation limits" or "daily limits." Under such daily limits, during a single trading day no trades may be executed at prices beyond the daily limit. If triggered, these limits could prevent the fund from liquidating unfavorable positions and subject the fund to losses or prevent it from entering into desired trades during the particular trading day. |
| FidelitySAIManagedFuturesFund-PRO | Fidelity SAI Managed Futures Fund | SwapsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Swaps Risk. The fund may invest in excess return and total return swaps. Swaps may be difficult to value and may be illiquid. The fund could experience losses if the underlying asset or reference does not perform as anticipated. Certain swaps have the potential for unlimited losses, regardless of the size of the initial investment. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | Risk Lose Money [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | You could lose money by investing in the fund. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | Risk Not Insured Depository Institution [Member] | |
| Prospectus Line Items | |
| Risk [Text Block] | An investment in the fund is not a deposit of a bank and is not insured or guaranteed by the Federal Deposit Insurance Corporation or any other government agency . |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | ContractsForDifferenceCfdRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Contracts for Difference (CFD) Risk. The fund may invest in Contracts for Difference (CFD), an OTC derivative total return swap transaction where the underlying reference asset will be a single equity stock or financial index. The fund could experience losses if the underlying asset or reference does not perform as anticipated. The fund may only close out a swap with its particular counterparty and may only transfer a position with the consent of that counterparty. Short CFD transactions have the potential for unlimited losses, regardless of the size of the initial investment. CFD agreements may be used to obtain exposure to a security or market without owning or taking physical custody of such security or investing directly in such market. CFD exposure may effectively add leverage to the fund's portfolio because, in addition to its total net assets, the fund would be subject to investment exposure on the notional amount of the swap. CFDs are subject to the risk that a counterparty will default on its payment obligations to the fund. CFD agreements also bear the risk that the fund will not be able to meet its obligation to the counterparty. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | ForeignCurrencyTransactionsMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign Currency Transactions. The fund may enter into forward foreign currency exchange contracts for hedging purposes. A forward foreign currency exchange contract, which involves an obligation to purchase or sell a specific currency at a future date at a price set at the time of the contract, reduces a fund's exposure to changes in the value of the currency it will deliver and increases its exposure to changes in the value of the currency it will receive for the duration of the contract. Foreign exchange rates can be extremely volatile and the degree of volatility of the market or in the direction of the market from that anticipated by the Adviser may result in losses to the fund. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | ShortSalesAndLeverageRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Short Sales and Leverage Risk. Short sales pose more risk than long positions. Because a short position loses value as the security's price increases, the loss on a short sale is theoretically unlimited. Regulatory bans on certain short selling activities may prevent a fund from fully implementing its strategy. Leverage can increase market exposure, magnify investment risks, and cause losses to be realized more quickly. The fund's use of derivative instruments may result in losses. The value of derivative instruments may pose risks in addition to and greater than those associated with investing directly in securities, currencies or other instruments and may be illiquid or less liquid, volatile, difficult to price and leveraged so that small changes in the value of underlying instruments may produce disproportionate losses to the fund. The use of derivatives is a highly specialized activity that involves investment techniques and risks different from those associated with investments in more traditional securities and instruments. Moreover, a relatively small price movement in a derivative contract may result in substantial losses to the fund, exceeding the amount of the margin paid. The use of derivatives can increase the fund's risk exposure to underlying assets and their attendant risks, while also exposing the fund to the risk of mispricing or other improper valuation and the risk that changes in the value of a derivative may not correlate as anticipated with the underlying asset, rate, index or overall securities markets, thereby reducing their effectiveness. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | FuturesContractRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Futures Contract Risk. The fund may invest in bond, currency, equity, index, and interest rate futures contracts. Certain futures contract markets are highly volatile, the use of futures may increase the volatility of the fund's net asset value per share (NAV), and futures contracts may be illiquid or less liquid than the underlying reference. Futures are traded on exchanges that may limit fluctuations in futures contract prices by imposing a maximum permissible daily price movement. The fund may be disadvantaged if it is prohibited from executing a trade outside the daily permissible price movement. Positions in futures contracts may be closed out only on the exchange on which they were entered into or through a linked exchange, and no secondary market exists for such contracts. Futures positions are marked to market each day and variation margin payment must be paid to or by the fund. Because of the low margin deposits normally required in futures trading, it is possible that the fund may employ a high degree of leverage in the portfolio. For certain types of futures contracts, losses are theoretically unlimited. Moreover, futures contracts executed (if any) on foreign exchanges may not provide the same protection as U.S. exchanges. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | USGovernmentObligationsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | U.S. Government Obligations Risk. Certain securities in which the fund may invest, including securities issued by certain U.S. Government agencies and U.S. Government sponsored enterprises, are not guaranteed by the U.S. Government or supported by the full faith and credit of the United States. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | GeographicExposureToEuropeMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Geographic Exposure to Europe. Because the fund invests a meaningful portion of its assets in Europe, the fund's performance is expected to be closely tied to social, political, and economic conditions within Europe and to be more volatile than the performance of more geographically diversified funds. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | ForeignAndEmergingMarketsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Foreign and Emerging Markets Risk. Foreign markets, particularly emerging markets, can be more volatile than the U.S. market due to increased risks of adverse issuer, political, regulatory, market, or economic developments and can perform differently from the U.S. market. The extent of economic development; political stability; market depth, infrastructure, and capitalization; and regulatory oversight can be less than in more developed markets. Emerging markets typically have less established legal, accounting and financial reporting systems than those in more developed markets, which may reduce the scope or quality of financial information available to investors. Emerging markets can be subject to greater social, economic, regulatory, and political uncertainties and can be extremely volatile. Foreign exchange rates also can be extremely volatile. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | IssuerSpecificChangesMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Issuer-Specific Changes. The value of an individual security or particular type of security can be more volatile than, and can perform differently from, the market as a whole. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | StockMarketVolatilityMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Stock Market Volatility. Stock markets are volatile and can decline significantly in response to adverse issuer, political, regulatory, market, or economic developments. Different parts of the market, including different market sectors, and different types of securities can react differently to these developments. |
| FidelityEquityMarketNeutralFund-RetailPRO | Fidelity Equity Market Neutral Fund | SwapsRiskMember | |
| Prospectus Line Items | |
| Risk [Text Block] | Swaps Risk. The fund may invest in excess return and total return swaps. Swaps may be difficult to value and may be illiquid. The fund could experience losses if the underlying asset or reference does not perform as anticipated. Certain swaps have the potential for unlimited losses, regardless of the size of the initial investment. |
| Document Type | 485BPOS |