Rafael Holdings, Inc. Spin-Off (Details) - USD ($) $ in Thousands	3 Months Ended
Oct. 31, 2018	Oct. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss before income taxes	$ 41	$ (381)
Rafael Holdings, Inc. Spin-Off [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss before income taxes		(539)
Loss before income taxes attributable to IDT Corporation		$ (498)

Amount of income (loss) from continuing operations, including income (loss) from equity method investments, before deduction of income tax expense (benefit), and income (loss) attributable to noncontrolling interest.

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