| Label                                             | **Element**              | Value                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                  |
|---------------------------------------------------|--------------------------|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| **Risk/Return:**                                  | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Registrant Name                                   | dei_EntityRegistrantName | FIDELITY INVESTMENT TRUST                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                              |
| Prospectus Date                                   | rr_ProspectusDate        | Dec. 29,				 2012                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                      |
| Retail | Fidelity Emerging Markets Discovery Fund |                          |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| **Risk/Return:**                                  | rr_RiskReturnAbstract    |                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                   |
| Supplement [Text Block]                           | fit_SupplementTextBlock  | **Supplement to the Fidelity® Emerging Markets Discovery Fund and Fidelity Total Emerging Markets Fund  December 29, 2012 Prospectus**The following information replaces similar information for Fidelity Emerging Markets Discovery fund found in the "Fund Summary" section under the heading "Fee Table" on page 4. 1 year$	1533 years$	7745 years$	1,44910 years$	3,254The following information replaces similar information for Fidelity Total Emerging Markets Fund found in the "Fund Summary" section under the heading "Fee Table" on page 8. 1 year$	1433 years$	4825 years$	84910 years$	1,881 |

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