No definition available.

Name:	IDT_DisclosureLeasesLineItem
Namespace Prefix:	IDT_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Description of lease term.

+ References

No definition available.

+ Details

Name:	IDT_LeaseTermDescription
Namespace Prefix:	IDT_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

New accounting pronouncement or change in accounting principle effect of adoptions quantification.

+ References

No definition available.

+ Details

Name:	IDT_NewAccountingPronouncementOrChangeInAccountingPrincipleEffectOfAdoptionsQuantification
Namespace Prefix:	IDT_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount of rent expense incurred for leased assets, including but not limited to, furniture and equipment, that is not directly or indirectly associated with the manufacture, sale or creation of a product or product line.

+ References

No definition available.

+ Details

Name:	us-gaap_LeaseAndRentalExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Term of lessor's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 30
-Section 50
-Paragraph 3
-Subparagraph (a)(3)
-URI http://asc.fasb.org/extlink&oid=124258985&loc=SL77919359-209981

+ Details

Name:	us-gaap_LessorOperatingLeaseRenewalTerm
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount of increase in right-of-use asset obtained in exchange for operating lease liability.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 55
-Paragraph 53
-URI http://asc.fasb.org/extlink&oid=123414884&loc=SL77918982-209971

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 842
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (g)(2)
-URI http://asc.fasb.org/extlink&oid=123408670&loc=SL77918686-209980

+ Details

Name:	us-gaap_RightOfUseAssetObtainedInExchangeForOperatingLeaseLiability
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Details

Name:	dei_LegalEntityAxis=IDT_RafaelHoldingsIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_GeographicDistributionAxis=IDT_NewarkMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_AdjustmentsForNewAccountingPronouncementsAxis=us-gaap_AccountingStandardsUpdate201602Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Leases (Details Narrative) - USD ($) $ in Millions		12 Months Ended
Leases (Details Narrative) - USD ($) $ in Millions	Sep. 01, 2020	Jul. 31, 2021	Jul. 31, 2020
DisclosureLeasesLineItem [Line Items]
Operating lease liability	$ 0.6
Rafael Holdings Inc. [Member]
DisclosureLeasesLineItem [Line Items]
Operating Leases, Rent Expense			$ 1.9
Newark [Member]
DisclosureLeasesLineItem [Line Items]
LeaseTermDescription		The Newark lease expires in April 2025 and the Israel lease expires in July 2025.
Accounting Standards Update 2016-02 [Member]
DisclosureLeasesLineItem [Line Items]
ASU 2016-02 Adoption			$ 12.4
Minimum [Member]
DisclosureLeasesLineItem [Line Items]
Lessor, Operating Lease, Renewal Term		1 year
Maximum [Member]
DisclosureLeasesLineItem [Line Items]
Lessor, Operating Lease, Renewal Term		4 years