| | | | | | | | | | | | | | | | | | | | | |
<?xml version="1.0" encoding="windows-1252"?> |
<FilingSummary> |
| <Version> 3.10.0.1 </Version> |
| <ProcessingTime/> |
| <ReportFormat> html </ReportFormat> |
| <ContextCount> 329 </ContextCount> |
| <ElementCount> 525 </ElementCount> |
| <EntityCount> 1 </EntityCount> |
| <FootnotesReported> true </FootnotesReported> |
| <SegmentCount> 98 </SegmentCount> |
| <ScenarioCount> 0 </ScenarioCount> |
| <TuplesReported> false </TuplesReported> |
| <UnitCount> 7 </UnitCount> |
| <MyReports> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R1.htm </HtmlFileName> |
| | | <LongName> 001 - Document - Document and Entity Information </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DocumentandEntityInformation </Role> |
| | | <ShortName> Document and Entity Information </ShortName> |
| | | <MenuCategory> Cover </MenuCategory> |
| | | <Position> 1 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R2.htm </HtmlFileName> |
| | | <LongName> 002 - Statement - Consolidated Balance Sheets </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedBalanceSheets </Role> |
| | | <ShortName> Consolidated Balance Sheets </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 2 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R3.htm </HtmlFileName> |
| | | <LongName> 003 - Statement - Consolidated Balance Sheets (Parenthetical) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedBalanceSheetsParenthetical </Role> |
| | | <ShortName> Consolidated Balance Sheets (Parenthetical) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 3 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R4.htm </HtmlFileName> |
| | | <LongName> 004 - Statement - Consolidated Statements of Income </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedStatementsOfIncome </Role> |
| | | <ShortName> Consolidated Statements of Income </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 4 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R5.htm </HtmlFileName> |
| | | <LongName> 005 - Statement - Consolidated Statements of Comprehensive Income </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedStatementsOfComprehensiveIncome </Role> |
| | | <ShortName> Consolidated Statements of Comprehensive Income </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 5 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R6.htm </HtmlFileName> |
| | | <LongName> 006 - Statement - Consolidated Statements of Equity </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedStatementsOfEquity </Role> |
| | | <ShortName> Consolidated Statements of Equity </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 6 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R7.htm </HtmlFileName> |
| | | <LongName> 007 - Statement - Consolidated Statements of Equity (Parenthetical) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedStatementsOfEquityParenthetical </Role> |
| | | <ShortName> Consolidated Statements of Equity (Parenthetical) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 7 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R8.htm </HtmlFileName> |
| | | <LongName> 008 - Statement - Consolidated Statements of Cash Flows </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedStatementsOfCashFlows </Role> |
| | | <ShortName> Consolidated Statements of Cash Flows </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 8 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R9.htm </HtmlFileName> |
| | | <LongName> 009 - Statement - Consolidated Statements of Cash Flows (Parenthetical) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ConsolidatedStatementsOfCashFlowsParenthetical </Role> |
| | | <ShortName> Consolidated Statements of Cash Flows (Parenthetical) </ShortName> |
| | | <MenuCategory> Statements </MenuCategory> |
| | | <Position> 9 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R10.htm </HtmlFileName> |
| | | <LongName> 010 - Disclosure - Description of Business and Summary of Significant Accounting Policies </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPolicies </Role> |
| | | <ShortName> Description of Business and Summary of Significant Accounting Policies </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 10 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R11.htm </HtmlFileName> |
| | | <LongName> 011 - Disclosure - Rafael Holdings, Inc. Spin-Off </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RafaelHoldingsIncSpinOff </Role> |
| | | <ShortName> Rafael Holdings, Inc. Spin-Off </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 11 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R12.htm </HtmlFileName> |
| | | <LongName> 012 - Disclosure - IDT Financial Services Holding Limited Assets and Liabilities Held for Sale </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IdtFinancialServicesHoldingLimitedAssetsAndLiabilitiesHeldForSale </Role> |
| | | <ShortName> IDT Financial Services Holding Limited Assets and Liabilities Held for Sale </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 12 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R13.htm </HtmlFileName> |
| | | <LongName> 013 - Disclosure - Zedge Spin-Off </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ZedgeSpinOff </Role> |
| | | <ShortName> Zedge Spin-Off </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 13 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R14.htm </HtmlFileName> |
| | | <LongName> 014 - Disclosure - Marketable Securities </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/MarketableSecurities </Role> |
| | | <ShortName> Marketable Securities </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 14 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R15.htm </HtmlFileName> |
| | | <LongName> 015 - Disclosure - Fair Value Measurements </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/FairValueMeasurements </Role> |
| | | <ShortName> Fair Value Measurements </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 15 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R16.htm </HtmlFileName> |
| | | <LongName> 016 - Disclosure - Property, Plant and Equipment </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/PropertyPlantAndEquipment </Role> |
| | | <ShortName> Property, Plant and Equipment </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 16 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R17.htm </HtmlFileName> |
| | | <LongName> 017 - Disclosure - Goodwill </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/Goodwill </Role> |
| | | <ShortName> Goodwill </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 17 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R18.htm </HtmlFileName> |
| | | <LongName> 018 - Disclosure - Sale of Member Interest in Visa Europe Ltd. </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SaleOfMemberInterestInVisaEuropeLtd </Role> |
| | | <ShortName> Sale of Member Interest in Visa Europe Ltd. </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 18 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R19.htm </HtmlFileName> |
| | | <LongName> 019 - Disclosure - Other Operating (Losses) Gains, Net </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/OtherOperatingLossesGainsNet </Role> |
| | | <ShortName> Other Operating (Losses) Gains, Net </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 19 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R20.htm </HtmlFileName> |
| | | <LongName> 020 - Disclosure - Revolving Credit Facility </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RevolvingCreditFacility </Role> |
| | | <ShortName> Revolving Credit Facility </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 20 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R21.htm </HtmlFileName> |
| | | <LongName> 021 - Disclosure - Accrued Expenses </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/AccruedExpenses </Role> |
| | | <ShortName> Accrued Expenses </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 21 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R22.htm </HtmlFileName> |
| | | <LongName> 022 - Disclosure - Severance Expense </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SeveranceExpense </Role> |
| | | <ShortName> Severance Expense </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 22 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R23.htm </HtmlFileName> |
| | | <LongName> 023 - Disclosure - Other (Expense) Income, Net </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/OtherExpenseIncomeNet </Role> |
| | | <ShortName> Other (Expense) Income, Net </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 23 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R24.htm </HtmlFileName> |
| | | <LongName> 024 - Disclosure - Income Taxes </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxes </Role> |
| | | <ShortName> Income Taxes </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 24 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R25.htm </HtmlFileName> |
| | | <LongName> 025 - Disclosure - Equity </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/Equity </Role> |
| | | <ShortName> Equity </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 25 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R26.htm </HtmlFileName> |
| | | <LongName> 026 - Disclosure - Stock-Based Compensation </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/StockBasedCompensation </Role> |
| | | <ShortName> Stock-Based Compensation </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 26 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R27.htm </HtmlFileName> |
| | | <LongName> 027 - Disclosure - Accumulated Other Comprehensive Loss </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/AccumulatedOtherComprehensiveLoss </Role> |
| | | <ShortName> Accumulated Other Comprehensive Loss </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 27 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R28.htm </HtmlFileName> |
| | | <LongName> 028 - Disclosure - Commitments and Contingencies </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/CommitmentsAndContingencies </Role> |
| | | <ShortName> Commitments and Contingencies </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 28 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R29.htm </HtmlFileName> |
| | | <LongName> 029 - Disclosure - Related Party Transactions </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RelatedPartyTransactions </Role> |
| | | <ShortName> Related Party Transactions </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 29 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R30.htm </HtmlFileName> |
| | | <LongName> 030 - Disclosure - Defined Contribution Plans </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DefinedContributionPlans </Role> |
| | | <ShortName> Defined Contribution Plans </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 30 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R31.htm </HtmlFileName> |
| | | <LongName> 031 - Disclosure - Business Segment Information </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/BusinessSegmentInformation </Role> |
| | | <ShortName> Business Segment Information </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 31 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R32.htm </HtmlFileName> |
| | | <LongName> 032 - Disclosure - Subsequent Event </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SubsequentEvent </Role> |
| | | <ShortName> Subsequent Event </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 32 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R33.htm </HtmlFileName> |
| | | <LongName> 033 - Disclosure - Selected Quarterly Financial Data (Unaudited) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SelectedQuarterlyFinancialDataUnaudited </Role> |
| | | <ShortName> Selected Quarterly Financial Data (Unaudited) </ShortName> |
| | | <MenuCategory> Notes </MenuCategory> |
| | | <Position> 33 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R34.htm </HtmlFileName> |
| | | <LongName> 034 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Policies) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesPolicies </Role> |
| | | <ShortName> Description of Business and Summary of Significant Accounting Policies (Policies) </ShortName> |
| | | <MenuCategory> Policies </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPolicies </ParentRole> |
| | | <Position> 34 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R35.htm </HtmlFileName> |
| | | <LongName> 035 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables </Role> |
| | | <ShortName> Description of Business and Summary of Significant Accounting Policies (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPolicies </ParentRole> |
| | | <Position> 35 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R36.htm </HtmlFileName> |
| | | <LongName> 036 - Disclosure - Rafael Holdings, Inc. Spin-Off (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RafaelHoldingsIncSpinOffTables </Role> |
| | | <ShortName> Rafael Holdings, Inc. Spin-Off (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RafaelHoldingsIncSpinOff </ParentRole> |
| | | <Position> 36 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R37.htm </HtmlFileName> |
| | | <LongName> 037 - Disclosure - IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IdtFinancialServicesHoldingLimitedAssetsAndLiabilitiesHeldForSaletables </Role> |
| | | <ShortName> IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IdtFinancialServicesHoldingLimitedAssetsAndLiabilitiesHeldForSale </ParentRole> |
| | | <Position> 37 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R38.htm </HtmlFileName> |
| | | <LongName> 038 - Disclosure - Zedge Spin-Off (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ZedgeSpinOffTables </Role> |
| | | <ShortName> Zedge Spin-Off (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/ZedgeSpinOff </ParentRole> |
| | | <Position> 38 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R39.htm </HtmlFileName> |
| | | <LongName> 039 - Disclosure - Marketable Securities (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/MarketableSecuritiesTables </Role> |
| | | <ShortName> Marketable Securities (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/MarketableSecurities </ParentRole> |
| | | <Position> 39 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R40.htm </HtmlFileName> |
| | | <LongName> 040 - Disclosure - Fair Value Measurements (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/FairValueMeasurementsTables </Role> |
| | | <ShortName> Fair Value Measurements (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/FairValueMeasurements </ParentRole> |
| | | <Position> 40 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R41.htm </HtmlFileName> |
| | | <LongName> 041 - Disclosure - Property, Plant and Equipment (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/PropertyPlantandEquipmentTables </Role> |
| | | <ShortName> Property, Plant and Equipment (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/PropertyPlantAndEquipment </ParentRole> |
| | | <Position> 41 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R42.htm </HtmlFileName> |
| | | <LongName> 042 - Disclosure - Goodwill (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/GoodwillTables </Role> |
| | | <ShortName> Goodwill (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/Goodwill </ParentRole> |
| | | <Position> 42 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R43.htm </HtmlFileName> |
| | | <LongName> 043 - Disclosure - Other Operating (Losses) Gains, Net (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/OtherOperatingLossesGainsNetTables </Role> |
| | | <ShortName> Other Operating (Losses) Gains, Net (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/OtherOperatingLossesGainsNet </ParentRole> |
| | | <Position> 43 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R44.htm </HtmlFileName> |
| | | <LongName> 044 - Disclosure - Accrued Expenses (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/AccruedExpensesTables </Role> |
| | | <ShortName> Accrued Expenses (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/AccruedExpenses </ParentRole> |
| | | <Position> 44 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R45.htm </HtmlFileName> |
| | | <LongName> 045 - Disclosure - Other (Expense) Income, Net (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/OtherExpenseIncomeNetTables </Role> |
| | | <ShortName> Other (Expense) Income, Net (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/OtherOperatingLossesGainsNet </ParentRole> |
| | | <Position> 45 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R46.htm </HtmlFileName> |
| | | <LongName> 046 - Disclosure - Income Taxes (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxesTables </Role> |
| | | <ShortName> Income Taxes (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IncomeTaxes </ParentRole> |
| | | <Position> 46 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R47.htm </HtmlFileName> |
| | | <LongName> 047 - Disclosure - Stock-Based Compensation (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/StockBasedCompensationTables </Role> |
| | | <ShortName> Stock-Based Compensation (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/StockBasedCompensation </ParentRole> |
| | | <Position> 47 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R48.htm </HtmlFileName> |
| | | <LongName> 048 - Disclosure - Accumulated Other Comprehensive Loss (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/AccumulatedOtherComprehensiveLossTables </Role> |
| | | <ShortName> Accumulated Other Comprehensive Loss (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/AccumulatedOtherComprehensiveLoss </ParentRole> |
| | | <Position> 48 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R49.htm </HtmlFileName> |
| | | <LongName> 049 - Disclosure - Commitments and Contingencies (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/CommitmentsAndContingenciesTables </Role> |
| | | <ShortName> Commitments and Contingencies (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/CommitmentsAndContingencies </ParentRole> |
| | | <Position> 49 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R50.htm </HtmlFileName> |
| | | <LongName> 050 - Disclosure - Related Party Transactions (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RelatedPartyTransactionsTables </Role> |
| | | <ShortName> Related Party Transactions (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RelatedPartyTransactions </ParentRole> |
| | | <Position> 50 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R51.htm </HtmlFileName> |
| | | <LongName> 051 - Disclosure - Business Segment Information (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/BusinessSegmentInformationTables </Role> |
| | | <ShortName> Business Segment Information (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/BusinessSegmentInformation </ParentRole> |
| | | <Position> 51 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R52.htm </HtmlFileName> |
| | | <LongName> 052 - Disclosure - Selected Quarterly Financial Data (Unaudited) (Tables) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SelectedQuarterlyFinancialDataUnauditedTables </Role> |
| | | <ShortName> Selected Quarterly Financial Data (Unaudited) (Tables) </ShortName> |
| | | <MenuCategory> Tables </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/SelectedQuarterlyFinancialDataUnaudited </ParentRole> |
| | | <Position> 52 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R53.htm </HtmlFileName> |
| | | <LongName> 053 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesDetails </Role> |
| | | <ShortName> Description of Business and Summary of Significant Accounting Policies (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables </ParentRole> |
| | | <Position> 53 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R54.htm </HtmlFileName> |
| | | <LongName> 054 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesDetails1 </Role> |
| | | <ShortName> Description of Business and Summary of Significant Accounting Policies (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables </ParentRole> |
| | | <Position> 54 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R55.htm </HtmlFileName> |
| | | <LongName> 055 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Details 2) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesDetails2 </Role> |
| | | <ShortName> Description of Business and Summary of Significant Accounting Policies (Details 2) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables </ParentRole> |
| | | <Position> 55 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R56.htm </HtmlFileName> |
| | | <LongName> 056 - Disclosure - Description of Business and Summary of Significant Accounting Policies (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DescriptionOfBusinessAndSummaryOfSignificantAccountingPoliciesDetailsTextual </Role> |
| | | <ShortName> Description of Business and Summary of Significant Accounting Policies (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/DescriptionofBusinessandSummaryofSignificantAccountingPoliciesTables </ParentRole> |
| | | <Position> 56 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R57.htm </HtmlFileName> |
| | | <LongName> 057 - Disclosure - Rafael Holdings, Inc. Spin-Off (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RafaelHoldingsIncSpinOffDetails </Role> |
| | | <ShortName> Rafael Holdings, Inc. Spin-Off (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RafaelHoldingsIncSpinOffTables </ParentRole> |
| | | <Position> 57 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R58.htm </HtmlFileName> |
| | | <LongName> 058 - Disclosure - Rafael Holdings, Inc. Spin-Off (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RafaelHoldingsIncSpinOffDetails1 </Role> |
| | | <ShortName> Rafael Holdings, Inc. Spin-Off (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RafaelHoldingsIncSpinOffTables </ParentRole> |
| | | <Position> 58 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R59.htm </HtmlFileName> |
| | | <LongName> 059 - Disclosure - Rafael Holdings, Inc. Spin-Off (Details 2) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RafaelHoldingsIncSpinOffDetails2 </Role> |
| | | <ShortName> Rafael Holdings, Inc. Spin-Off (Details 2) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RafaelHoldingsIncSpinOffTables </ParentRole> |
| | | <Position> 59 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R60.htm </HtmlFileName> |
| | | <LongName> 060 - Disclosure - Rafael Holdings, Inc. Spin-Off (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RafaelHoldingsIncSpinOffDetailsTextual </Role> |
| | | <ShortName> Rafael Holdings, Inc. Spin-Off (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RafaelHoldingsIncSpinOffTables </ParentRole> |
| | | <Position> 60 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R61.htm </HtmlFileName> |
| | | <LongName> 061 - Disclosure - IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/Idtfinancialservicesholdinglimitedassetsandliabilitiesheldforsaledetails </Role> |
| | | <ShortName> IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IdtFinancialServicesHoldingLimitedAssetsAndLiabilitiesHeldForSaletables </ParentRole> |
| | | <Position> 61 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R62.htm </HtmlFileName> |
| | | <LongName> 062 - Disclosure - IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/Idtfinancialservicesholdinglimitedassetsandliabilitiesheldforsaledetails1 </Role> |
| | | <ShortName> IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IdtFinancialServicesHoldingLimitedAssetsAndLiabilitiesHeldForSaletables </ParentRole> |
| | | <Position> 62 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R63.htm </HtmlFileName> |
| | | <LongName> 063 - Disclosure - IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/Idtfinancialservicesholdinglimitedassetsandliabilitiesheldforsaledetailstextual </Role> |
| | | <ShortName> IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IdtFinancialServicesHoldingLimitedAssetsAndLiabilitiesHeldForSaletables </ParentRole> |
| | | <Position> 63 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R64.htm </HtmlFileName> |
| | | <LongName> 064 - Disclosure - Zedge Spin-Off (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/ZedgeSpinOffDetails </Role> |
| | | <ShortName> Zedge Spin-Off (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/ZedgeSpinOffTables </ParentRole> |
| | | <Position> 64 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R65.htm </HtmlFileName> |
| | | <LongName> 065 - Disclosure - Marketable Securities (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/MarketableSecuritiesDetails </Role> |
| | | <ShortName> Marketable Securities (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/MarketableSecuritiesTables </ParentRole> |
| | | <Position> 65 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R66.htm </HtmlFileName> |
| | | <LongName> 066 - Disclosure - Marketable Securities (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/MarketableSecuritiesDetails1 </Role> |
| | | <ShortName> Marketable Securities (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/MarketableSecuritiesTables </ParentRole> |
| | | <Position> 66 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R67.htm </HtmlFileName> |
| | | <LongName> 067 - Disclosure - Marketable Securities (Details 2) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/MarketableSecuritiesDetails2 </Role> |
| | | <ShortName> Marketable Securities (Details 2) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/MarketableSecuritiesTables </ParentRole> |
| | | <Position> 67 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R68.htm </HtmlFileName> |
| | | <LongName> 068 - Disclosure - Marketable Securities (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/MarketableSecuritiesDetailsTextual </Role> |
| | | <ShortName> Marketable Securities (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/MarketableSecuritiesTables </ParentRole> |
| | | <Position> 68 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R69.htm </HtmlFileName> |
| | | <LongName> 069 - Disclosure - Fair Value Measurements (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/FairValueMeasurementsDetails </Role> |
| | | <ShortName> Fair Value Measurements (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/FairValueMeasurementsTables </ParentRole> |
| | | <Position> 69 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R70.htm </HtmlFileName> |
| | | <LongName> 070 - Disclosure - Fair Value Measurements (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/Fairvaluemeasurementsdetails1 </Role> |
| | | <ShortName> Fair Value Measurements (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/FairValueMeasurementsTables </ParentRole> |
| | | <Position> 70 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R71.htm </HtmlFileName> |
| | | <LongName> 071 - Disclosure - Fair Value Measurements (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/FairValueMeasurementsDetailsTextual </Role> |
| | | <ShortName> Fair Value Measurements (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/FairValueMeasurementsTables </ParentRole> |
| | | <Position> 71 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R72.htm </HtmlFileName> |
| | | <LongName> 072 - Disclosure - Property, Plant and Equipment (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/PropertyPlantandEquipmentDetails </Role> |
| | | <ShortName> Property, Plant and Equipment (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/PropertyPlantandEquipmentTables </ParentRole> |
| | | <Position> 72 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R73.htm </HtmlFileName> |
| | | <LongName> 073 - Disclosure - Property, Plant and Equipment (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/PropertyPlantAndEquipmentDetailsTextual </Role> |
| | | <ShortName> Property, Plant and Equipment (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/PropertyPlantandEquipmentTables </ParentRole> |
| | | <Position> 73 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R74.htm </HtmlFileName> |
| | | <LongName> 074 - Disclosure - Goodwill (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/GoodwillDetails </Role> |
| | | <ShortName> Goodwill (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/GoodwillTables </ParentRole> |
| | | <Position> 74 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R75.htm </HtmlFileName> |
| | | <LongName> 075 - Disclosure - Sale of Member Interest in Visa Europe Ltd. (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SaleofMemberInterestinVisaEuropeLtdDetails </Role> |
| | | <ShortName> Sale of Member Interest in Visa Europe Ltd. (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/SaleOfMemberInterestInVisaEuropeLtd </ParentRole> |
| | | <Position> 75 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R76.htm </HtmlFileName> |
| | | <LongName> 076 - Disclosure - Other Operating (Losses) Gains, Net (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/OtherOperatingLossesGainsNetDetails </Role> |
| | | <ShortName> Other Operating (Losses) Gains, Net (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/OtherOperatingLossesGainsNetTables </ParentRole> |
| | | <Position> 76 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R77.htm </HtmlFileName> |
| | | <LongName> 077 - Disclosure - Other Operating (Losses) Gains, Net (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/Otheroperatingexpensesgainsnetdetailstextual </Role> |
| | | <ShortName> Other Operating (Losses) Gains, Net (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/OtherOperatingLossesGainsNetTables </ParentRole> |
| | | <Position> 77 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R78.htm </HtmlFileName> |
| | | <LongName> 078 - Disclosure - Revolving Credit Facility (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RevolvingCreditFacilityDetails </Role> |
| | | <ShortName> Revolving Credit Facility (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RevolvingCreditFacility </ParentRole> |
| | | <Position> 78 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R79.htm </HtmlFileName> |
| | | <LongName> 079 - Disclosure - Accrued Expenses (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/AccruedExpensesDetails </Role> |
| | | <ShortName> Accrued Expenses (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/AccruedExpensesTables </ParentRole> |
| | | <Position> 79 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R80.htm </HtmlFileName> |
| | | <LongName> 080 - Disclosure - Severance Expense (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SeveranceExpenseDetails </Role> |
| | | <ShortName> Severance Expense (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/SeveranceExpense </ParentRole> |
| | | <Position> 80 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R81.htm </HtmlFileName> |
| | | <LongName> 081 - Disclosure - Other (Expense) Income, Net (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/OtherExpenseIncomeNetDetails </Role> |
| | | <ShortName> Other (Expense) Income, Net (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/OtherOperatingLossesGainsNetTables </ParentRole> |
| | | <Position> 81 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R82.htm </HtmlFileName> |
| | | <LongName> 082 - Disclosure - Income Taxes (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxesDetails </Role> |
| | | <ShortName> Income Taxes (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IncomeTaxesTables </ParentRole> |
| | | <Position> 82 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R83.htm </HtmlFileName> |
| | | <LongName> 083 - Disclosure - Income Taxes (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxesDetails1 </Role> |
| | | <ShortName> Income Taxes (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IncomeTaxesTables </ParentRole> |
| | | <Position> 83 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R84.htm </HtmlFileName> |
| | | <LongName> 084 - Disclosure - Income Taxes (Details 2) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxesDetails2 </Role> |
| | | <ShortName> Income Taxes (Details 2) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IncomeTaxesTables </ParentRole> |
| | | <Position> 84 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R85.htm </HtmlFileName> |
| | | <LongName> 085 - Disclosure - Income Taxes (Details 3) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxesDetails3 </Role> |
| | | <ShortName> Income Taxes (Details 3) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IncomeTaxesTables </ParentRole> |
| | | <Position> 85 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R86.htm </HtmlFileName> |
| | | <LongName> 086 - Disclosure - Income Taxes (Details 4) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxesDetails4 </Role> |
| | | <ShortName> Income Taxes (Details 4) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IncomeTaxesTables </ParentRole> |
| | | <Position> 86 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R87.htm </HtmlFileName> |
| | | <LongName> 087 - Disclosure - Income Taxes (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/IncomeTaxesDetailsTextual </Role> |
| | | <ShortName> Income Taxes (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/IncomeTaxesTables </ParentRole> |
| | | <Position> 87 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R88.htm </HtmlFileName> |
| | | <LongName> 088 - Disclosure - Equity (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/EquityDetails </Role> |
| | | <ShortName> Equity (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/Equity </ParentRole> |
| | | <Position> 88 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R89.htm </HtmlFileName> |
| | | <LongName> 089 - Disclosure - Stock-Based Compensation (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/StockBasedCompensationDetails </Role> |
| | | <ShortName> Stock-Based Compensation (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/StockBasedCompensationTables </ParentRole> |
| | | <Position> 89 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R90.htm </HtmlFileName> |
| | | <LongName> 090 - Disclosure - Stock-Based Compensation (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/StockBasedCompensationDetails1 </Role> |
| | | <ShortName> Stock-Based Compensation (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/StockBasedCompensationTables </ParentRole> |
| | | <Position> 90 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R91.htm </HtmlFileName> |
| | | <LongName> 091 - Disclosure - Stock-Based Compensation (Details 2) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/StockBasedCompensationDetails2 </Role> |
| | | <ShortName> Stock-Based Compensation (Details 2) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/StockBasedCompensationTables </ParentRole> |
| | | <Position> 91 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R92.htm </HtmlFileName> |
| | | <LongName> 092 - Disclosure - Stock-Based Compensation (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/StockBasedCompensationDetailsTextual </Role> |
| | | <ShortName> Stock-Based Compensation (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/StockBasedCompensationTables </ParentRole> |
| | | <Position> 92 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R93.htm </HtmlFileName> |
| | | <LongName> 093 - Disclosure - Accumulated Other Comprehensive Loss (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/AccumulatedOtherComprehensiveLossDetails </Role> |
| | | <ShortName> Accumulated Other Comprehensive Loss (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/AccumulatedOtherComprehensiveLossTables </ParentRole> |
| | | <Position> 93 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R94.htm </HtmlFileName> |
| | | <LongName> 094 - Disclosure - Accumulated Other Comprehensive Loss (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/AccumulatedOtherComprehensiveLossDetailsTextual </Role> |
| | | <ShortName> Accumulated Other Comprehensive Loss (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/AccumulatedOtherComprehensiveLossTables </ParentRole> |
| | | <Position> 94 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R95.htm </HtmlFileName> |
| | | <LongName> 095 - Disclosure - Commitments and Contingencies (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/CommitmentsAndContingenciesDetails </Role> |
| | | <ShortName> Commitments and Contingencies (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/CommitmentsAndContingenciesTables </ParentRole> |
| | | <Position> 95 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R96.htm </HtmlFileName> |
| | | <LongName> 096 - Disclosure - Commitments and Contingencies (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/CommitmentsAndContingenciesDetailsTextual </Role> |
| | | <ShortName> Commitments and Contingencies (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/CommitmentsAndContingenciesTables </ParentRole> |
| | | <Position> 96 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R97.htm </HtmlFileName> |
| | | <LongName> 097 - Disclosure - Related Party Transactions (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RelatedPartyTransactionsDetails </Role> |
| | | <ShortName> Related Party Transactions (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RelatedPartyTransactionsTables </ParentRole> |
| | | <Position> 97 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R98.htm </HtmlFileName> |
| | | <LongName> 098 - Disclosure - Related Party Transactions (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/RelatedPartyTransactionsDetailsTextual </Role> |
| | | <ShortName> Related Party Transactions (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/RelatedPartyTransactionsTables </ParentRole> |
| | | <Position> 98 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R99.htm </HtmlFileName> |
| | | <LongName> 099 - Disclosure - Defined Contribution Plans (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/DefinedContributionPlansDetails </Role> |
| | | <ShortName> Defined Contribution Plans (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/DefinedContributionPlans </ParentRole> |
| | | <Position> 99 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R100.htm </HtmlFileName> |
| | | <LongName> 100 - Disclosure - Business Segment Information (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/BusinessSegmentInformationDetails </Role> |
| | | <ShortName> Business Segment Information (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/BusinessSegmentInformationTables </ParentRole> |
| | | <Position> 100 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R101.htm </HtmlFileName> |
| | | <LongName> 101 - Disclosure - Business Segment Information (Details 1) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/BusinessSegmentInformationDetails1 </Role> |
| | | <ShortName> Business Segment Information (Details 1) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/BusinessSegmentInformationTables </ParentRole> |
| | | <Position> 101 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R102.htm </HtmlFileName> |
| | | <LongName> 102 - Disclosure - Business Segment Information (Details 2) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/BusinessSegmentInformationDetails2 </Role> |
| | | <ShortName> Business Segment Information (Details 2) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/BusinessSegmentInformationTables </ParentRole> |
| | | <Position> 102 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R103.htm </HtmlFileName> |
| | | <LongName> 103 - Disclosure - Business Segment Information (Details 3) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/BusinessSegmentInformationDetails3 </Role> |
| | | <ShortName> Business Segment Information (Details 3) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/BusinessSegmentInformationTables </ParentRole> |
| | | <Position> 103 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R104.htm </HtmlFileName> |
| | | <LongName> 104 - Disclosure - Business Segment Information (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/BusinessSegmentInformationDetailsTextual </Role> |
| | | <ShortName> Business Segment Information (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/BusinessSegmentInformationTables </ParentRole> |
| | | <Position> 104 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R105.htm </HtmlFileName> |
| | | <LongName> 105 - Disclosure - Subsequent Event (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SubsequentEventDetails </Role> |
| | | <ShortName> Subsequent Event (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/SubsequentEvent </ParentRole> |
| | | <Position> 105 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R106.htm </HtmlFileName> |
| | | <LongName> 106 - Disclosure - Selected Quarterly Financial Data (Unaudited) (Details) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SelectedQuarterlyFinancialDataUnauditedDetails </Role> |
| | | <ShortName> Selected Quarterly Financial Data (Unaudited) (Details) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/SelectedQuarterlyFinancialDataUnauditedTables </ParentRole> |
| | | <Position> 106 </Position> |
| | | </Report> |
| | <Report instance="idt-20180731.xml"> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <HtmlFileName> R107.htm </HtmlFileName> |
| | | <LongName> 107 - Disclosure - Selected Quarterly Financial Data (Unaudited) (Details Textual) </LongName> |
| | | <ReportType> Sheet </ReportType> |
| | | <Role> http://www.idt.net/role/SelectedQuarterlyFinancialDataUnauditedDetailsTextual </Role> |
| | | <ShortName> Selected Quarterly Financial Data (Unaudited) (Details Textual) </ShortName> |
| | | <MenuCategory> Details </MenuCategory> |
| | | <ParentRole> http://www.idt.net/role/SelectedQuarterlyFinancialDataUnauditedTables </ParentRole> |
| | | <Position> 107 </Position> |
| | | </Report> |
| | <Report> |
| | | <IsDefault> false </IsDefault> |
| | | <HasEmbeddedReports> false </HasEmbeddedReports> |
| | | <LongName> All Reports </LongName> |
| | | <ReportType> Book </ReportType> |
| | | <ShortName> All Reports </ShortName> |
| | | </Report> |
| | </MyReports> |
| <InputFiles> |
| | <File> idt-20180731.xml </File> |
| | <File> idt-20180731.xsd </File> |
| | <File> idt-20180731_cal.xml </File> |
| | <File> idt-20180731_def.xml </File> |
| | <File> idt-20180731_lab.xml </File> |
| | <File> idt-20180731_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://xbrl.sec.gov/invest/2013-01-31 </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> |