Consolidated Statements of Income (Unaudited) - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		6 Months Ended
	Jan. 31, 2017	Jan. 31, 2016	Jan. 31, 2017	Jan. 31, 2016
Consolidated Statements of Income [Abstract]
Revenues	$ 367,556	$ 382,454	$ 736,707	$ 773,032
Costs and expenses:
Direct cost of revenues (exclusive of depreciation and amortization)	310,913	319,724	623,941	644,235
Selling, general and administrative (i)	47,325	51,054	92,763	104,143
Depreciation and amortization	5,301	4,973	10,601	10,025
Total costs and expenses	363,539	375,751	727,305	758,403
Other operating expense	(889)	(326)	(1,088)	(326)
Income from operations	3,128	6,377	8,314	14,303
Interest income, net	309	534	609	692
Other (expense) income, net	(419)	(234)	1,974	(844)
Income before income taxes	3,018	6,677	10,897	14,151
(Provision for) benefit from income taxes	(1,761)	(2,014)	12,655	(4,911)
Net income	1,257	4,663	23,552	9,240
Net income attributable to noncontrolling interests	(382)	(598)	(758)	(981)
Net income attributable to IDT Corporation	$ 875	$ 4,065	$ 22,794	$ 8,259
Earnings per share attributable to IDT Corporation common stockholders:
Basic	$ 0.04	$ 0.18	$ 1.00	$ 0.36
Diluted	$ 0.04	$ 0.18	$ 0.99	$ 0.36
Weighted-average number of shares used in calculation of earnings per share:
Basic	22,768	22,799	22,740	22,867
Diluted	22,963	22,799	22,931	22,884
Dividends declared per common share	$ 0.19	$ 0.19	$ 0.38	$ 0.37
(i) Stock-based compensation included in selling, general and administrative expenses	$ 1,426	$ 873	$ 2,128	$ 1,644