XML 117 R98.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Accumulated Other Comprehensive Income (Loss) (Details Textual) - USD ($) $ in Thousands | 12 Months Ended
--- | ---
Jul. 31, 2017 | Jul. 31, 2016 | Jul. 31, 2015
Schedule of accumulated balances for each classification of other comprehensive income (loss) |  |  |  |
Net other comprehensive income (loss) attributable to IDT Corporation | $ 1,401 |  | $ (5,544) | $ (2,999)
Unrealized gain (loss) on available-for-sale securities [Member] |  |  |  |
Schedule of accumulated balances for each classification of other comprehensive income (loss) |  |  |  |
Net other comprehensive income (loss) attributable to IDT Corporation | 2,126 | [1] | $ 583 |
Unrealized gain (loss) on available-for-sale securities [Member] | Marketable Securities [Member] |  |  |  |
Schedule of accumulated balances for each classification of other comprehensive income (loss) |  |  |  |
Net other comprehensive income (loss) attributable to IDT Corporation | 26 |  |  |
Unrealized gain (loss) on available-for-sale securities [Member] | Rafael Pharmaceuticals, Inc. [Member] |  |  |  |
Schedule of accumulated balances for each classification of other comprehensive income (loss) |  |  |  |
Net other comprehensive income (loss) attributable to IDT Corporation | $ 2,100 |  |  |
[1] | In fiscal 2017, net other comprehensive income attributable to IDT Corporation from unrealized gains on available-for-sale securities included unrealized gains on the Rafael convertible promissory notes of $2.1 million and unrealized gains, net on marketable securities of $26,000.

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

X
- Definition Amount after tax and reclassification adjustments of other comprehensive income (loss). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 505 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21463-112644 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1A -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669619-108580 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 45 -Paragraph 1B -URI http://asc.fasb.org/extlink&oid=84228862&loc=SL7669625-108580 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 220 -SubTopic 10 -Section 55 -Paragraph 15 -URI http://asc.fasb.org/extlink&oid=84158357&loc=d3e1436-108581 + Details
Name: | us-gaap_OtherComprehensiveIncomeLossNetOfTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementEquityComponentsAxis=us-gaap_AccumulatedNetUnrealizedInvestmentGainLossMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_MajorTypesOfDebtAndEquitySecuritiesAxis=idt_MarketableSecuritiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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