Name:	idt_CashAndCashEquivalentsSubstantiallyRestricted
Namespace Prefix:	idt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Commitments and contingencies.

No definition available.

Name:	idt_CommitmentsAndContingenciesTextualAbstract
Namespace Prefix:	idt_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

Loss contingency payment aggregate paid to related party.

No definition available.

Name:	idt_LossContingencyPaymentAggregatePaidToRelatedParty
Namespace Prefix:	idt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Loss contingency payment for assets.

No definition available.

Name:	idt_LossContingencyPaymentForAssets
Namespace Prefix:	idt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Loss contingency payment for settlement and release.

No definition available.

Name:	idt_LossContingencyPaymentForSettlementAndRelease
Namespace Prefix:	idt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Percentage of license net proceeds to be paid to related party stockholders.

No definition available.

Name:	idt_PercentageOfLicenseNetProceedsToBePaidToRelatedPartyStockholders
Namespace Prefix:	idt_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

In certain circumstances, the company is required to provide performance bonds in connection with its contractual commitments. Company has indemnified the surety for any expenses paid out under these performance bonds.

No definition available.

Name:	idt_PerformanceBondsOutstanding
Namespace Prefix:	idt_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Related party transaction sale to related party amount.

No definition available.

Name:	idt_RelatedPartyTransactionSaleToRelatedPartyAmount
Namespace Prefix:	idt_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

Carrying value as of the balance sheet date of obligations incurred and payable, pertaining to costs that are statutory in nature, are incurred on contractual obligations, or accumulate over time and for which invoices have not yet been received or will not be rendered. Examples include taxes, interest, rent and utilities.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.15(5))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03.15(a))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Name:	us-gaap_AccruedLiabilitiesCurrentAndNoncurrent
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

The designation of funds furnished by a borrower to a lender to assure future payments of the borrower's real estate taxes and insurance obligations with respect to a mortgaged property. Escrow deposits may be made for a variety of other purposes such as earnest money and contingent payments. This element excludes replacement reserves which are an escrow separately provided for within the US GAAP taxonomy.

Name:	us-gaap_EscrowDeposit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

Name:	us-gaap_OtherCommitment
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

Amount of general expenses not normally included in Other Operating Costs and Expenses.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.6)
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

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

Minimum amount of purchase arrangement in which the entity has agreed to expend funds to procure goods or services from a supplier.

No definition available.