| **Risk/Return Summary - FidelityInternationalSmallCapFund-AMCIZPRO - FidelityInternationalSmallCapFund-AMCIZPRO - Fidelity International Small Cap Fund** | Dec. 30, 2024                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| Risk Lose Money [Text]                                                                                                                                    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| **Prospectus Line Items**                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Risk Text Block                                                                                                                                           |               You could lose money by investing in the fund.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                       |
| Risk Not Insured Depository Institution [Text]                                                                                                            |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| **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             .                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                         |
| 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.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                               |
| GeographicExposureToJapanMember                                                                                                                           |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| **Prospectus Line Items**                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Risk Text Block                                                                                                                                           | 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.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 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.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| 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.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
| 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.                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                          |
| ForeignExposureMember                                                                                                                                     |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| **Prospectus Line Items**                                                                                                                                 |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Risk Text Block                                                                                                                                           | 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. |

| X                                                                                                                                                                                                                                                    |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form N-1A
+ Details**Name:**rr_ProspectusLineItems**Namespace Prefix:**rr_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                  |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Text block containing a risk heading and narrative for a single risk.
+ References
Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form N-1A -Section 4 -Subsection b -Paragraph 1 -Subparagraph i -Clause instruction
+ Details**Name:**rr_RiskTextBlock**Namespace Prefix:**rr_**Data Type:**dtr-types:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**dei_DocumentInformationDocumentAxis=fmr_FidelityInternationalSmallCapFund-AMCIZPROMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                |
|----------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**dei_LegalEntityAxis=fmr_S000007104Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                          |
|----------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=rr_RiskLoseMoneyMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                                |
|--------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=rr_RiskNotInsuredDepositoryInstitutionMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                        |
|------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=fmr_GeographicExposureToEuropeMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                       |
|-----------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=fmr_GeographicExposureToJapanMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=fmr_IssuerSpecificChangesMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                                   |
|-------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=fmr_StockMarketVolatilityMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                               |
|---------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=fmr_SmallCapInvestingMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |
| X                                                                                                                             |
|-------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**rr_RiskAxis=fmr_ForeignExposureMember**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** |