XML 100 R81.htm IDEA: XBRL DOCUMENT v3.8.0.1

Other Operating Losses, Net (Details Textual) - USD ($) $ in Millions		1 Months Ended	12 Months Ended
	Apr. 09, 2017	Apr. 29, 2017	Jul. 31, 2017
Other Operating Expenses (Textual)
Stockholders, ownership percentage	22.00%
Ownership interest exchange	$ 6.0
Liability related to the settlement and mutual release	10.0
Legal fees on settlement and mutual release			$ 0.9
Proceeds related to the FCC investigation			$ 0.5
Straight Path [Member]
Other Operating Expenses (Textual)
Settlement and mutual release payment	10.0	$ 10.0
Straight Path IP Group [Member]
Other Operating Expenses (Textual)
Settlement and mutual release payment	$ 6.0

X

- Definition

The amount of loss contingency expected payment for assets.

+ References

No definition available.

+ Details

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

X

- Definition

Loss contingency legal fees in period other general expense.

+ References

No definition available.

+ Details

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

X

- Definition

Loss contingency loss in period other general expense.

+ References

No definition available.

+ Details

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

X

- References

No definition available.

+ Details

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

X

- Definition

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

+ References

No definition available.

+ Details

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

X

- Definition

Related party transaction sale to related party amount.

+ References

No definition available.

+ Details

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

X

- Definition

The amount of loss pertaining to the specified contingency that was charged against earnings in the period, including the effects of revisions in previously reported estimates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 450
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=82911808&loc=d3e14326-108349

+ Details

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

X

- Definition

Amount of insurance proceeds for an event or transaction that is unusual in nature or infrequent in occurrence, or both.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 20
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=64828382&loc=d3e15138-107781

+ Details

Name:	us-gaap_UnusualOrInfrequentItemInsuranceProceeds
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- Details

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

X

- Details

Name:	us-gaap_RelatedPartyTransactionsByRelatedPartyAxis=idt_StraightPathIpGroupMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: