XML 87 R68.htm IDEA: XBRL DOCUMENT
v3.8.0.1

Marketable Securities (Details) - USD ($) $ in Thousands | Jul. 31, 2017 | Jul. 31, 2016
--- | --- | ---
Available-for-sale securities: |  |  |
Amortized Cost |  | $ 58,238 | $ 52,941
Gross Unrealized Gains, Total |  | 82 | 189
Gross Unrealized Losses, Total |  | (48) | (181)
Fair Value |  | 58,272 | 52,949
Certificates of deposit [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost | [1] | 29,011 | 17,690
Gross Unrealized Gains | [1] | 1 | 6
Gross Unrealized Losses | [1] | (7) |
Fair Value | [1] | 29,005 | 17,696
Federal Government Sponsored Enterprise notes [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost |  | 3,992 | 3,457
Gross Unrealized Gains |  |  | 17
Gross Unrealized Losses |  | (14) |
Fair Value |  | 3,978 | 3,474
International agency notes [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost |  | 291 | 409
Gross Unrealized Gains |  |  | 5
Gross Unrealized Losses |  |  |
Fair Value |  | 291 | 414
Mutual funds [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost |  | 5,353 | 5,121
Gross Unrealized Gains |  | 77 |
Gross Unrealized Losses |  |  | (39)
Fair Value |  | 5,430 | 5,082
Corporate bonds [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost |  | 4,643 | 3,633
Gross Unrealized Gains |  |  | 40
Gross Unrealized Losses |  |  |
Fair Value |  | 4,643 | 3,673
Equity [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost |  | 74 | 2,463
Gross Unrealized Gains |  |  |
Gross Unrealized Losses |  | (26) | (140)
Fair Value |  | 48 | 2,323
U.S. Treasury notes [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost |  | 6,673 | 4,946
Gross Unrealized Gains |  |  | 95
Gross Unrealized Losses |  |  | (1)
Fair Value |  | 6,673 | 5,040
Municipal bonds [Member] |  |  |
Available-for-sale securities: |  |  |
Amortized Cost |  | 8,201 | 15,222
Gross Unrealized Gains |  | 4 | 26
Gross Unrealized Losses |  | (1) | (1)
Fair Value |  | $ 8,204 | $ 15,247
[1] | Each of the Company's certificates of deposit has a CUSIP, was purchased in the secondary market through a broker and may be sold in the secondary market.

X
- Definition Amount of unrealized gain before deducting unrealized loss on investments in debt securities classified as available-for-sale securities. + References No definition available. + Details
Name: | idt_AvailableForSaleSecuritiesTotalGrossUnrealizedGains
Namespace Prefix: | idt_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of unrealized loss before deducting unrealized gain on investments in available-for-sale debt securities. + References No definition available. + Details
Name: | idt_AvailableForSaleSecuritiesTotalGrossUnrealizedLosses
Namespace Prefix: | idt_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in debt securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleDebtSecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Amount before tax of unrealized gain in accumulated other comprehensive income (AOCI) on investments in equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedGainBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount before tax of unrealized loss in accumulated other comprehensive income (AOCI) on investments in equity securities classified as available-for-sale. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 50 -Paragraph 2 -Subparagraph (c) -URI http://asc.fasb.org/extlink&oid=82897076&loc=d3e27161-111563 + Details
Name: | us-gaap_AvailableForSaleEquitySecuritiesAccumulatedGrossUnrealizedLossBeforeTax
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition This item represents the cost of debt and equity securities, which are categorized neither as held-to-maturity nor trading, net of adjustments including accretion, amortization, collection of cash, previous other-than-temporary impairments recognized in earnings (less any cumulative-effect adjustments recognized, as defined), and fair value hedge accounting adjustments, if any. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_AvailableForSaleSecuritiesAmortizedCost
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

X
- Definition Amount of investments in debt and equity securities, including, but not limited to, held-to-maturity, trading and available-for-sale expected to be converted to cash, sold or exchanged within one year or the normal operating cycle, if longer. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section 45 -Paragraph 1 -Subparagraph (f) -URI http://asc.fasb.org/extlink&oid=82887183&loc=d3e6676-107765 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 320 -SubTopic 10 -Section 45 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=82896770&loc=d3e26626-111562 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.2) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 + Details
Name: | us-gaap_MarketableSecuritiesCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

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

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

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

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

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

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

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

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