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| | <File> idt-20190131_pre.xml </File> |
| | </InputFiles> |
| <SupplementalFiles/> |
| <BaseTaxonomies> |
| | <BaseTaxonomy> http://fasb.org/us-gaap/2018-01-31 </BaseTaxonomy> |
| | <BaseTaxonomy> http://xbrl.sec.gov/country/2017-01-31 </BaseTaxonomy> |
| | <BaseTaxonomy> http://fasb.org/srt/2018-01-31 </BaseTaxonomy> |
| | <BaseTaxonomy> http://xbrl.sec.gov/dei/2018-01-31 </BaseTaxonomy> |
| | </BaseTaxonomies> |
| <HasPresentationLinkbase> true </HasPresentationLinkbase> |
| <HasCalculationLinkbase> true </HasCalculationLinkbase> |
| </FilingSummary> |