| Label                                            | **Element**              | Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            |
|--------------------------------------------------|--------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Risk/Return:**                                 | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Registrant Name                                  | dei_EntityRegistrantName | FIDELITY INVESTMENT TRUST                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                        |
| Prospectus Date                                  | rr_ProspectusDate        | Dec. 29,				 2012                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                |
| A T C | Fidelity Emerging Markets Discovery Fund |                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| **Risk/Return:**                                 | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                             |
| Supplement [Text Block]                          | fit_SupplementTextBlock  | **Supplement to the Fidelity Advisor® Emerging Markets Discovery Fund Class A, Class T, and Class C December 29, 2012 Prospectus**The following information replaces similar information found in the "Fund Summary" section under the heading "Fee Table" on page 4.  **Class A****Class T****Class C** Sell All SharesHold SharesSell All SharesHold SharesSell All SharesHold Shares1 year$	743$	743$	546$	546$	353$	2533 years$	1,414$	1,414$	1,286$	1,286$	1,125$	1,1255 years$	2,136$	2,136$	2,075$	2,075$	2,041$	2,04110 years$	4,034$	4,034$	4,130$	4,130$	4,381$	4,381 |

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