Risk/Return Detail Data - FidelityInternationalCapitalAppreciationK6Fund-PRO	Dec. 30, 2022 USD ($)
Risk/Return:
Registrant Name	Fidelity Investment Trust
FidelityInternationalCapitalAppreciationK6Fund-PRO | Fidelity International Capital Appreciation K6 Fund
Risk/Return:
Risk/Return [Heading]	Fund Summary Fund: Fidelity® International Capital Appreciation K6 Fund
Objective [Heading]	Investment Objective
Objective, Primary [Text Block]	Fidelity® International Capital Appreciation K6 Fund seeks long-term growth of capital.
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 the fund.
Shareholder Fees Caption [Text]	Shareholder fees
(fees paid directly from your investment)	none
Operating Expenses Caption [Text]	Annual Operating Expenses
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. During the most recent fiscal year, the fund's portfolio turnover rate was 119 % of the average value of its portfolio.
Portfolio Turnover, Rate	119.00%
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 primarily in common stocks. 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. 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. 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. 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]	The following information is intended to help you understand the risks of investing in the fund. The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time. The index description appears in the "Additional Index Information" section of the prospectus. Past performance is not an indication of future performance. Visit www.401k.com and log in for more recent performance information.
Performance Information Illustrates Variability of Returns [Text]	The information illustrates the changes in the performance of the fund's shares from year to year and compares the performance of the fund's shares to the performance of a securities market index over various periods of time.
Performance Availability Website Address [Text]	www.401k.com
Performance Past Does Not Indicate Future [Text]	Past performance is not an indication of future performance.
Bar Chart [Heading]	Year-by-Year Returns
Annual Return, Inception Date	May 25, 2017
Year to Date Return, Label	Year-to-Date Return
Bar Chart, Year to Date Return, Date	Sep. 30, 2022
Bar Chart, Year to Date Return	(34.82%)
Highest Quarterly Return, Label	Highest Quarter Return
Highest Quarterly Return, Date	Jun. 30, 2020
Highest Quarterly Return	19.15%
Lowest Quarterly Return, Label	Lowest Quarter Return
Lowest Quarterly Return, Date	Mar. 31, 2020
Lowest Quarterly Return	(16.91%)
Performance Table Heading	Average Annual Returns
FidelityInternationalCapitalAppreciationK6Fund-PRO | Fidelity International Capital Appreciation K6 Fund | Fidelity International Capital Appreciation K6 Fund
Risk/Return:
Management fee	0.65%
Distribution and/or Service (12b-1) fees	none
Other expenses	none
Total annual operating expenses	0.65%
1 year	$ 66
3 years	208
5 years	362
10 years	$ 810
2018	(12.55%)
2019	33.52%
2020	22.82%
2021	12.53%
FidelityInternationalCapitalAppreciationK6Fund-PRO | Fidelity International Capital Appreciation K6 Fund | Return Before Taxes | Fidelity International Capital Appreciation K6 Fund
Risk/Return:
Label	Fidelity® International Capital Appreciation K6 Fund
Past 1 year	12.53%
Since Inception	14.07%
FidelityInternationalCapitalAppreciationK6Fund-PRO | Fidelity International Capital Appreciation K6 Fund | MS112
Risk/Return:
Label	MSCI ACWI (All Country World Index) ex USA Index
Past 1 year	7.98%
Since Inception	7.52%	[1]

[1] A From May 25, 2017