Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017
Consolidated Statements of Operations [Abstract]
Revenues	$ 365,410	$ 370,035	$ 1,154,848	$ 1,106,742
Costs and expenses:
Direct cost of revenues (exclusive of depreciation and amortization)	307,165	314,704	980,903	938,646
Selling, general and administrative (i)	50,136	46,196	152,565	138,958
Depreciation and amortization	5,799	5,474	17,207	16,075
Severance	3,658		4,293
Total costs and expenses	366,758	366,374	1,154,968	1,093,679
Other operating expenses	(345)	(10,163)	(1,970)	(11,251)
(Loss) income from operations	(1,693)	(6,502)	(2,090)	1,812
Interest income, net	204	295	853	905
Other (expense) income, net	(712)	(407)	(1,168)	1,565
(Loss) income before income taxes	(2,201)	(6,614)	(2,405)	4,282
(Provision for) benefit from income taxes	(1,029)	2,162	(931)	14,817
Net (loss) income	(3,230)	(4,452)	(3,336)	19,099
Net income attributable to noncontrolling interests	(228)	(323)	(698)	(1,081)
Net (loss) income attributable to IDT Corporation	$ (3,458)	$ (4,775)	$ (4,034)	$ 18,018
(Loss) earnings per share attributable to IDT Corporation common stockholders:
Basic	$ (0.14)	$ (0.21)	$ (0.16)	$ 0.79
Diluted	$ (0.14)	$ (0.21)	$ (0.16)	$ 0.78
Weighted-average number of shares used in calculation of (loss) earnings per share:
Basic	24,675	23,054	24,649	22,845
Diluted	24,675	23,054	24,649	22,989
Dividends declared per common share	$ 0.09	$ 0.19	$ 0.47	$ 0.57
(i) Stock-based compensation included in selling, general and administrative expenses	$ 1,033	$ 666	$ 2,842	$ 2,793