Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012	Jul. 31, 2011
Income Statement [Abstract]
REVENUES	$ 1,620,617	$ 1,506,283	$ 1,351,416
COSTS AND EXPENSES:
Direct cost of revenues (exclusive of depreciation and amortization)	1,355,573	1,269,386	1,119,606
Selling, general and administrative	218,469	206,906	202,410
Depreciation and amortization	14,910	16,648	20,952
Research and development	7,166	4,569	2,834
Impairment of building and improvements	4,359
Severance and other charges			1,053
TOTAL COSTS AND EXPENSES	1,600,477	1,497,509	1,346,855
Other operating gains (losses), net	9,251	(15,870)	2,824
Income (loss) from operations	29,391	(7,096)	7,385
Interest expense, net	(824)	(2,985)	(3,698)
Other income (expense), net	5,383	(1,767)	3,912
Income (loss) from continuing operations before income taxes	33,950	(11,848)	7,599
(Provision for) benefit from income taxes	(15,872)	42,782	13,388
Income from continuing operations	18,078	30,934	20,987
Discontinued operations, net of tax:
(Loss) income from discontinued operations	(4,634)	5,851	(1,116)
Income on sale of discontinued operations		2,000	3,500
Total discontinued operations	(4,634)	7,851	2,384
NET INCOME	13,444	38,785	23,371
Net (income) loss attributable to noncontrolling interests	(1,837)	(137)	3,441
Net income attributable to IDT corporation	11,607	38,648	26,812
Amounts attributable to IDT Corporation common stockholders:
Income from continuing operations	16,048	29,901	20,244
(Loss) income from discontinued operations	(4,441)	8,747	6,568
Net income attributable to IDT corporation	11,607	38,648	26,812
Basic:
Income from continuing operations	$ 0.77	$ 1.45	$ 0.98
(Loss) income from discontinued operations	$ (0.21)	$ 0.42	$ 0.32
Net income	$ 0.56	$ 1.87	$ 1.30
Weighted-average number of shares used in calculation of basic earnings per share	20,876	20,717	20,565
Diluted:
Income from continuing operations	$ 0.72	$ 1.36	$ 0.90
(Loss) income from discontinued operations	$ (0.20)	$ 0.39	$ 0.29
Net income	$ 0.52	$ 1.75	$ 1.19
Weighted-average number of shares used in calculation of diluted earnings per share	22,315	22,060	22,482
Stock-based compensation included in selling, general and administrative expenses	$ 5,875	$ 3,325	$ 3,414