| Label                                         | **Element**              | Value                                                                                                                                                                                                                                                                                          |
|-----------------------------------------------|--------------------------|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Risk/Return:**                              | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                           |
| Registrant Name                               | dei_EntityRegistrantName | FIDELITY INVESTMENT TRUST                                                                                                                                                                                                                                                                      |
| Prospectus Date                               | rr_ProspectusDate        | Dec. 30,  2014                                                                                                                                                                                                                                                                                 |
| Retail | Fidelity Total Emerging Markets Fund |                          |                                                                                                                                                                                                                                                                                           |
| **Risk/Return:**                              | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                           |
| Supplement [Text Block]                       | fit_SupplementTextBlock  | **Supplement to theFidelity® Emerging Markets Discovery Fund and Fidelity Total Emerging Markets FundDecember 30, 2014Prospectus**Effective October 1, 2015, Fidelity® Emerging Markets Discovery Fund changed its classification from a non-diversified fund to a diversified fund. |

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The date of the prospectus.
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