Rafael Holdings, Inc. Spin-Off (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2019	Jul. 31, 2018	Jul. 31, 2017
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(LOSS) INCOME BEFORE INCOME TAXES	$ 453	$ 8,101	$ 7,620
Rafael Holdings, Inc. Spin-Off [Member]
Income Statement, Balance Sheet and Additional Disclosures by Disposal Groups, Including Discontinued Operations [Line Items]
(LOSS) INCOME BEFORE INCOME TAXES		(2,410)	520
(LOSS) INCOME BEFORE INCOME TAXES ATTRIBUTABLE TO IDT CORPORATION		$ (2,107)	$ 517