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| | | <ShortName> Defined Contribution Plan (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://idt.net/role/DefinedContributionPlan </ParentRole> |
| | | <Position> 76 </Position> |
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| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <LongName> All Reports </LongName> |
| | | <ReportType> Book </ReportType> |
| | | <ShortName> All Reports </ShortName> |
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| | <File> idt-20200430.xsd </File> |
| | <File> idt-20200430_cal.xml </File> |
| | <File> idt-20200430_def.xml </File> |
| | <File> idt-20200430_lab.xml </File> |
| | <File> idt-20200430_pre.xml </File> |
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