Consolidated Statements of Comprehensive Income (Loss) (Unaudited) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Consolidated Statements of Comprehensive Income [Abstract]
Net income (loss)	$ 489	$ 1,690	$ (659)	$ (106)
Other comprehensive (loss) income:
Change in unrealized loss on available-for-sale securities	3	(120)	1	(150)
Foreign currency translation adjustments	(41)	330	483	(38)
Other comprehensive (loss) income	(38)	210	484	(188)
Comprehensive income (loss)	451	1,900	(175)	(294)
Comprehensive income attributable to noncontrolling interests	(300)	(174)	(601)	(470)
Comprehensive income (loss) attributable to IDT Corporation	$ 151	$ 1,726	$ (776)	$ (764)