XML 122 R103.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Related Party Transactions (Details) - Straight Path [Member] - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Jul. 31, 2017 | Jul. 31, 2016
Estimated liability to straight path included in other current liabilities |  |
Balance at beginning of year | $ 133 | $ 286
Additional liability | 104 | 59
Adjustments | (51) | (136)
Payments | (105) | (76)
Balance at end of year | $ 81 | $ 133

X
- Definition Change in balance of estimated liability additional liability. + References No definition available. + Details
Name: | idt_ChangeInBalanceOfEstimatedLiabilityAdditionalLiability
Namespace Prefix: | idt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Change in balance of estimated liability adjustments. + References No definition available. + Details
Name: | idt_ChangeInBalanceOfEstimatedLiabilityAdjustments
Namespace Prefix: | idt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition Change in balance of estimated liability included in other current liabilities. + References No definition available. + Details
Name: | idt_ChangeInBalanceOfEstimatedLiabilityIncludedInOtherCurrentLiabilities
Namespace Prefix: | idt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Change in balance of estimated liability payments. + References No definition available. + Details
Name: | idt_ChangeInBalanceOfEstimatedLiabilityPayments
Namespace Prefix: | idt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- References No definition available. + Details
Name: | idt_ScheduleOfChangesInCompanysEstimatedLiabilityAbstract
Namespace Prefix: | idt_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=idt_StraightPathMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |