Risk/Return Detail Data - FidelitySustainableEmergingMarketsEquityFundFidelitySustainableInternationalEquityFund-RetailComboPRO	Dec. 30, 2022 USD ($)
Risk/Return:
Registrant Name	Fidelity Investment Trust
FidelitySustainableEmergingMarketsEquityFundFidelitySustainableInternationalEquityFund-RetailComboPRO | Fidelity Sustainable Emerging Markets Equity Fund
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund /Class: Fidelity® Sustainable Emerging Markets Equity Fund /Fidelity® Sustainable Emerging Markets Equity Fund
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity® Sustainable Emerging Markets Equity Fund seeks capital appreciation.
Expense [Heading]	Fee Table
Expense Narrative [Text Block]	The following table describes the fees and expenses that may be incurred when you buy and hold shares of the fund. In addition to the fees and expenses described below, your broker may also require you to pay brokerage commissions on purchases and sales of certain share classes of the fund.
Shareholder Fees Caption [Text]	Shareholder fees
(fees paid directly from your investment)	none
Operating Expenses Caption [Text]	Annual Operating Expenses
Fee Waiver or Reimbursement over Assets, Date of Termination	Feb. 29, 2024
Portfolio Turnover [Heading]	Portfolio Turnover
Portfolio Turnover [Text Block]	The fund pays transaction costs, such as commissions, when it buys and sells securities (or "turns over" its portfolio). A higher portfolio turnover rate may indicate higher transaction costs and may result in higher taxes when fund shares are held in a taxable account. These costs, which are not reflected in annual operating expenses or in the example, affect the fund's performance. For the period from February 10, 2022 to October 31, 2022, the fund's portfolio turnover rate was 84 % (annualized) of the average value of its portfolio.
Portfolio Turnover, Rate	84.00%
Expenses Not Correlated to Ratio Due to Acquired Fund Fees [Text]	Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus, in part, because of acquired fund fees and expenses. As a result, the total annual operating expenses after fee waiver and/or expense reimbursement in the fee table exceed the contractual expense limitation of the fund.
Expense Example Narrative [Text Block]	This example helps compare the cost of investing in the fund with the cost of investing in other funds.Let's say, hypothetically, that the annual return for shares of the fund is 5% and that the fees and the annual operating expenses for shares of the fund are exactly as described in the fee table. This example illustrates the effect of fees and expenses, but is not meant to suggest actual or expected fees and expenses or returns, all of which may vary. For every $10,000 you invested, here's how much you would pay in total expenses if you sell all of your shares at the end of each time period indicated:
Strategy [Heading]	Principal Investment Strategies
Strategy Narrative [Text Block]	Normally investing at least 80% of assets in equity securities of companies in emerging markets, including equity investments that are tied economically to emerging markets, that Fidelity Management & Research Company LLC (FMR) (the Adviser) believes have proven or improving sustainability practices based on an evaluation of such companies' individual environmental, social, and governance (ESG) profile. Emerging markets include countries that have an emerging stock market as defined by MSCI, countries or markets with low- to- middle-income economies as classified by the World Bank, and other countries or markets with similar emerging characteristics. Normally investing primarily in equity securities. Using the Adviser's proprietary ESG ratings process to evaluate the current state of an issuer's sustainability practices using a data-driven framework that includes both proprietary and third-party data, and also provide a qualitative forward-looking assessment of an issuer's sustainability outlook provided by the Adviser's fundamental research analysts and ESG team. The Adviser's ESG ratings of issuers are derived from multiple factors, including an issuer's environmental profile, which may include, but is not limited to, carbon and toxic emissions, water management, waste management, vulnerability to the physical impacts of climate change, and research and investment into products, services, and energies that reduce emissions and/or provide opportunities to transition to less carbon-intensive products or operations. An assessment of an issuer's social profile includes, but is not limited to, its approach to diversity and inclusion, human capital management, data privacy, product safety and human rights. With respect to governance, the independence and diversity of an issuer's board, its compensation practices and board oversight of critical ESG issues are considered as part of the assessment. These factors are weighted based on how material the Adviser believes each factor is to an issuer's financial outlook, and not all factors may be applicable to all issuers. Investing in issuers that the Adviser believes deliver tangible environmental or social impact through core business operations. An assessment of the impact characteristics of an issuer may involve corporate engagement and an analysis of issuer alignment with the United Nations Sustainable Development Goals using qualitative analysis as well as proprietary or third-party data. For example, issuers that provide access to clean water, education, or clean energy through their core business may be considered to deliver tangible impact. Allocating investments across different emerging markets countries. In addition to the ESG ratings process, using fundamental analysis of factors such as each issuer's financial condition and industry position, as well as market and economic conditions, to select investments. Employing sustainable investing exclusion criteria to avoid investments in issuers that are directly engaged in, and/or derive significant revenue from, certain industries. Please see "Fund Basics - Investment Details - Sustainable Investing Exclusions" for additional information.
Risk [Heading]	Principal Investment Risks
Risk Narrative [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. Sustainability Risk. Application of FMR's ESG ratings process and/or its sustainable investing exclusion criteria may affect the fund's exposure to certain issuers, sectors, regions, and countries and may affect the fund's performance depending on whether certain investments are in or out of favor. The criteria related to the fund's ESG ratings process and/or adherence to its sustainable investing exclusion criteria may result in the fund forgoing opportunities to buy certain securities when it might otherwise be advantageous to do so, or selling securities for ESG reasons when it might be otherwise disadvantageous for it to do so. As a result, the fund's performance may at times be better or worse than the performance of funds that do not use ESG or sustainability criteria. There are significant differences in interpretations of what it means for an issuer to have positive ESG factors. While the Adviser believes its definitions are reasonable, the portfolio decisions it makes may differ with other investors' or advisers' views. When evaluating an issuer, the Adviser is dependent on information or data obtained through voluntary or third-party reporting that may be incomplete, inaccurate, or unavailable, which could cause the Adviser to incorrectly assess an issuer's business practices. 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. Geographic Exposure to China. Because the fund invests a meaningful portion of its assets in China, the fund's performance is expected to be closely tied to social, political, and economic conditions in China and to be more volatile than the performance of more geographically diversified funds. The fund may obtain exposure to companies based or operated in China by investing through legal structures known as variable interest entities (VIEs). Instead of directly owning the equity securities of a Chinese company, a VIE enters into service and other contracts with the Chinese company. Although the VIE has no equity ownership of the Chinese company, the contractual arrangements permit the VIE to consolidate the Chinese company into its financial statements. Intervention by the Chinese government with respect to VIEs could significantly affect the Chinese company's performance and the enforceability of the VIE's contractual arrangements with the Chinese company. 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. Management Risk The Adviser's application of the fund's strategy criteria may not achieve its intended results. The fund could underperform in comparison to other funds with a similar benchmark or similar objectives and investment strategies . 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 .   You could lose money by investing in the fund.
Risk Lose Money [Text]	You could lose money by investing in the fund.
Risk Not Insured Depository Institution [Text]	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 .
Bar Chart and Performance Table [Heading]	Performance
Performance Narrative [Text Block]	Performance history will be available for the fund after the fund has been in operation for one calendar year.
Performance One Year or Less [Text]	Performance history will be available for the fund after the fund has been in operation for one calendar year.
FidelitySustainableEmergingMarketsEquityFundFidelitySustainableInternationalEquityFund-RetailComboPRO | Fidelity Sustainable Emerging Markets Equity Fund | Fidelity Sustainable Emerging Markets Equity Fund
Risk/Return:
Management fee	0.78%	[1]
Distribution and/or Service (12b-1) fees	none
Other expenses	7.29%
Acquired fund fees and expenses	0.03%
Total annual operating expenses	8.10%	[2]
Fee waiver and/or expense reimbursement	6.82%	[3]
Total annual operating expenses after fee waiver and/or expense reimbursement	1.28%	[2]
1 year	$ 130
3 years	1,552
5 years	3,118
10 years	$ 6,625

[1] A The management fee is comprised of a basic fee of 0.78% adjusted up or down by a maximum of 0.10% based on the fund's performance relative to that of the MSCI Emerging Markets Index. Please see "Fund Services - Fund Management - Advisory Fee(s)" for additional information.

[2] B Differs from the ratios of expenses to average net assets in the Financial Highlights section of the prospectus, in part, because of acquired fund fees and expenses. As a result, the total annual operating expenses after fee waiver and/or expense reimbursement in the fee table exceed the contractual expense limitation of the fund.

[3] C Fidelity Management & Research Company LLC (FMR) has contractually agreed to reimburse the class of shares of the fund to the extent that total operating expenses (excluding interest, certain taxes, fees and expenses of the Independent Trustees, extraordinary expenses, and acquired fund fees and expenses (including fees and expenses associated with a wholly owned subsidiary), if any, as well as non-operating expenses such as brokerage commissions and fees and expenses associated with the fund's securities lending program, if applicable), as a percentage of its average net assets, exceed 1.25% (the Expense Cap). If at any time during the current fiscal year expenses for the class of shares of the class of shares of the fund fall below the Expense Cap, FMR reserves the right to recoup through the end of the fiscal year any expenses that were reimbursed during the current fiscal year up to, but not in excess of, the Expense Cap. This arrangement will remain in effect through February 29, 2024 . FMR may not terminate this arrangement before the expiration date without the approval of the Board of Trustees and may extend it in its discretion after that date.