Risk/Return Detail Data - FidelitySeriesSelectInternationalSmallCapFund-PRO	Dec. 30, 2023 USD ($)
Risk/Return:
Registrant Name	Fidelity Investment Trust
FidelitySeriesSelectInternationalSmallCapFund-PRO | Fidelity Series Select International Small Cap Fund
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund: Fidelity® Series Select International Small Cap Fund
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity® Series Select International Small Cap 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, hold, and sell shares 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	February 28, 2027
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 November 4, 2022 to October 31, 2023, the fund's portfolio turnover rate was 23% (annualized) of the average value of its portfolio.
Portfolio Turnover, Rate	23.00%
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 primarily in non-U.S. securities, including securities of issuers located in emerging markets. 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 that the Adviser identifies as having similar emerging markets characteristics.Normally investing at least 80% of assets in securities of companies with small market capitalizations (which, for purposes of this fund, are those companies with market capitalizations similar to companies in the MSCI EAFE Small Cap Index or the MSCI ACWI ex USA Small Cap Index).Normally investing primarily in equity securities.Allocating investments across different countries and regions.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.
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. Foreign Exposure. 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 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. Geographic Exposure to Japan. Because the fund invests a meaningful portion of its assets in Japan, the fund's performance is expected to be closely tied to social, political, and economic conditions within Japan and to be more volatile than the performance of more geographically diversified funds. 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. 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. 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.
FidelitySeriesSelectInternationalSmallCapFund-PRO | Fidelity Series Select International Small Cap Fund | Fidelity Series Select International Small Cap Fund
Risk/Return:
Management fee	none
Distribution and/or Service (12b-1) fees	none
Other expenses	0.23%
Total annual operating expenses	0.23%
Fee waiver and/or expense reimbursement	0.22%	[1]
Total annual operating expenses after fee waiver and/or expense reimbursement	0.01%
1 year	$ 1
3 years	3
5 years	50
10 years	$ 215

[1] AFidelity Management & Research Company LLC (FMR) has contractually agreed to reimburse the fund to the extent that total operating expenses (excluding interest, fees and expenses of the Independent Trustees, 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 0.013% (the Expense Cap). If at any time during the current fiscal year expenses for 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 28, 2027. 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.