| Label                                           | **Element**              | Value                                                                                                                                                                                                                                                                                                                                    |
|-------------------------------------------------|--------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Risk/Return:**                                | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                                                                     |
| Registrant Name                                 | dei_EntityRegistrantName | FIDELITY INVESTMENT TRUST                                                                                                                                                                                                                                                                                                                |
| Prospectus Date                                 | rr_ProspectusDate        | Dec. 29,				 2012                                                                                                                                                                                                                                                                                                                        |
| Inst | Fidelity Emerging Markets Discovery Fund |                          |                                                                                                                                                                                                                                                                                                                                     |
| **Risk/Return:**                                | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                                                                     |
| Supplement [Text Block]                         | fit_SupplementTextBlock  | **Supplement to the Fidelity Advisor® Emerging Markets Discovery Fund Institutional Class December 29, 2012 Prospectus**The following information replaces similar information found in the "Fund Summary" section under the heading "Fee Table" on page 4. 1 year$	1533 years$	8105 years$	1,52310 years$	3,416 |

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