|**Shareholder Fees - FidelityInternationalSmallCapFund-AMCIZPRO - FidelityInternationalSmallCapFund-AMCIZPRO - Fidelity International Small Cap Fund**                                                                                                                                                                                                                                     | Dec. 30, 2024                                                                                                                                                                                                                                                                         
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|Fidelity Advisor International Small Cap Fund - Class A                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                       
|**Shareholder Fees:**                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                       
|Maximum sales charge (load) on purchases (as a % of offering price)                                                                                                                                                                                                                                                                                                                        | 5.75%                                                                                                                                                                                                                                                                                 
|Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)                                                                                                                                                                                                                                                                          | none                                                                                                                                                                                                                                                                                  
|Fidelity Advisor International Small Cap Fund - Class C                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                       
|**Shareholder Fees:**                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                       
|Maximum sales charge (load) on purchases (as a % of offering price)                                                                                                                                                                                                                                                                                                                        | none                                                                                                                                                                                                                                                                                  
|Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)                                                                                                                                                                                                                                                                          | 1.00%                                                                                                                                                                                                                                                                                 
|Fidelity Advisor International Small Cap Fund - Class M                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                       
|**Shareholder Fees:**                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                       
|Maximum sales charge (load) on purchases (as a % of offering price)                                                                                                                                                                                                                                                                                                                        | 3.50%                                                                                                                                                                                                                                                                                 
|Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)                                                                                                                                                                                                                                                                          | none                                                                                                                                                                                                                                                                                  
|Fidelity Advisor International Small Cap Fund - Class I                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                       
|**Shareholder Fees:**                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                       
|Maximum sales charge (load) on purchases (as a % of offering price)                                                                                                                                                                                                                                                                                                                        | none                                                                                                                                                                                                                                                                                  
|Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)                                                                                                                                                                                                                                                                          | none                                                                                                                                                                                                                                                                                  
|Fidelity Advisor International Small Cap Fund - Class Z                                                                                                                                                                                                                                                                                                                                    |                                                                                                                                                                                                                                                                                       
|**Shareholder Fees:**                                                                                                                                                                                                                                                                                                                                                                      |                                                                                                                                                                                                                                                                                       
|Maximum sales charge (load) on purchases (as a % of offering price)                                                                                                                                                                                                                                                                                                                        | none                                                                                                                                                                                                                                                                                  
|Maximum contingent deferred sales charge (as a % of the lesser of original purchase price or redemption proceeds)                                                                                                                                                                                                                                                                          | none                                                                                                                                                                                                                                                                                  
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|[1]A                          Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% and 0.25%, respectively.[2]B                          On Class C shares redeemed less than one year after purchase. | [1]                                                                                                                                                                                                                                                                                   
|[1]                                                                                                                                                                                                                                                                                                                                                                                        | A                          Class A and Class M purchases of $1 million or more will not be subject to a front-end sales charge. Such Class A and Class M purchases may be subject, upon redemption, to a contingent deferred sales charge (CDSC) of 1.00% and 0.25%, respectively.
|[2]                                                                                                                                                                                                                                                                                                                                                                                        | B                          On Class C shares redeemed less than one year after purchase.                                                                                                                                                                                          

X- DefinitionMaximum Sales Charge (Load) Imposed on Purchases (as a percentage of offering price). If a sales charge (load) is imposed on shares purchased with reinvested capital gains distributions or returns of capital, include the bracketed words in the third caption.+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form N-1A -Section 3 -Subsection table -Paragraph 1 -Subparagraph 1+ Details**Name:**rr_MaximumCumulativeSalesChargeOverOfferingPrice**Namespace Prefix:**rr_**Data Type:**rr:NonNegativePure4Type**Balance Type:**na**Period Type:**duration X- DefinitionMaximum Deferred Sales Charge (Load) (as a percentage of ____)  "Maximum Deferred Sales Charge (Load)" includes the maximum total deferred sales charge (load) payable upon redemption, in installments, or both, expressed as a percentage of the amount or amounts stated in response to Item 7(a), except that, for a sales charge (load) based on net asset value at the time of purchase, show the sales charge (load) as a percentage of the offering price at the time of purchase. A Fund may include in a footnote to the table, if applicable, a tabular presentation showing the amount of deferred sales charges (loads) over time or a narrative explanation of the sales charges (loads) (e.g., __% in the first year after purchase, declining to __% in the __ year and eliminated thereafter).  If more than one type of sales charge (load) is imposed (e.g., a deferred sales charge (load) and a front-end sales charge (load)), the first caption in the table should read "Maximum Sales Charge (Load)" and show the maximum cumulative percentage. Show the percentage amounts and the terms of each sales charge (load) comprising that figure on separate lines below.+ ReferencesReference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Form N-1A -Section 3 -Subsection instructions -Paragraph 2 -Subparagraph a -Clause i+ Details**Name:**rr_MaximumDeferredSalesChargeOverOther**Namespace Prefix:**rr_**Data Type:**rr:NonNegativePure4Type**Balance Type:**na**Period Type:**duration X- ReferencesNo definition available.+ Details**Name:**rr_ShareholderFeesAbstract**Namespace Prefix:**rr_**Data Type:**xbrli:stringItemType**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_ProspectusShareClassAxis=fmr_C000019424Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** X- Details**Name:**rr_ProspectusShareClassAxis=fmr_C000019426Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** X- Details**Name:**rr_ProspectusShareClassAxis=fmr_C000019427Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** X- Details**Name:**rr_ProspectusShareClassAxis=fmr_C000019428Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:** X- Details**Name:**rr_ProspectusShareClassAxis=fmr_C000205030Member**Namespace Prefix:****Data Type:**na**Balance Type:****Period Type:**