XML 45 R34.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Spin-Off of Rafael Holdings, Inc. and Investment in Rafael Pharmaceuticals, Inc. (Details) - Rafael Pharma [Member] - USD ($) $ in Thousands | Jan. 31, 2018 | Jul. 31, 2017
--- | --- | ---
Schedule of consolidated balance sheets |  |
Series D Note (at fair value) | $ 6,300 | $ 6,300
Warrants (at cost) | 5,400 | 5,400
Right to receive additional shares (at cost) |  | 400
Total investment in Rafael Pharma | $ 11,700 | $ 12,100

X
- Definition Value of right to receive additional shares. + References No definition available. + Details
Name: | idt_RightToReceiveAdditionalShares
Namespace Prefix: | idt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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

X
- Definition Fair value portion of borrowing which can be exchanged for a specified number of another security at the option of the issuer or the holder, for example, but not limited to, the entity's common stock. + References No definition available. + Details
Name: | us-gaap_ConvertibleDebtFairValueDisclosures
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Cost of the investment. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 210 -Section 50 -Paragraph 6 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=63488139&loc=d3e12121-115841 + Details
Name: | us-gaap_InvestmentOwnedAtCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Value of outstanding derivative securities that permit the holder the right to purchase securities (usually equity) from the issuer at a specified price. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(i)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 + Details
Name: | us-gaap_WarrantsAndRightsOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | invest_InvestmentAxis=idt_RafaelPharmaceuticalsIncMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |