Consolidated Statements of Operations (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2019	Jan. 31, 2018	Jan. 31, 2019	Jan. 31, 2018
Consolidated Statements of Operations [Abstract]
Revenues	$ 349,473	$ 395,883	$ 711,789	$ 789,438
Costs and expenses:
Direct cost of revenues (exclusive of depreciation and amortization)	291,178	337,229	595,870	673,738
Selling, general and administrative	50,900	52,358	101,452	102,429
Depreciation and amortization	5,762	5,735	11,357	11,408
Severance		195		635
Total costs and expenses	347,840	395,517	708,679	788,210
Other operating expense, net	(90)	(846)	(285)	(1,625)
Income (loss) from operations	1,543	(480)	2,825	(397)
Interest income, net	186	286	295	648
Other income (expense), net	496	370	(853)	(456)
Income (loss) before income taxes	2,225	176	2,267	(205)
(Provision for) benefit from income taxes	(1,736)	1,514	(2,926)	99
Net income (loss)	489	1,690	(659)	(106)
Net income attributable to noncontrolling interests	(300)	(174)	(601)	(470)
Net income (loss) attributable to IDT Corporation	$ 189	$ 1,516	$ (1,260)	$ (576)
Earnings (loss) per share attributable to IDT Corporation common stockholders:
Basic	$ 0.01	$ 0.06	$ (0.05)	$ (0.02)
Diluted	$ 0.01	$ 0.06	$ (0.05)	$ (0.02)
Weighted-average number of shares used in calculation of earnings (loss) per share:
Basic	24,816	24,643	24,323	24,635
Diluted	24,821	24,724	24,323	24,635
(i) Stock-based compensation included in selling, general and administrative expenses	$ 467	$ 987	$ 880	$ 1,797