IDT Financial Services Holding Limited Assets and Liabilities Held for Sale (Details 1) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss before income taxes	$ 2,225	$ 176	$ 2,267	$ (205)
IDT Financial Services Holding Limited [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
Loss before income taxes	(437)	(559)	(470)	(1,009)
Loss before income taxes attributable to IDT Corporation	$ (437)	$ (559)	$ (470)	$ (1,009)