Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	12 Months Ended
	Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Income Statement [Abstract]
REVENUES	$ 1,651,541	$ 1,620,617	$ 1,506,283
COSTS AND EXPENSES:
Direct cost of revenues (exclusive of depreciation and amortization)	1,367,266	1,355,573	1,269,386
Selling, general and administrative (i)	228,934	218,469	206,906
Depreciation and amortization	16,318	14,910	16,648
Research and development	10,018	7,166	4,569
Impairment of building and improvements		4,359
TOTAL COSTS AND EXPENSES	1,622,536	1,600,477	1,497,509
Other operating gains (losses), net	835	9,251	(15,870)
Income (loss) from operations	29,840	29,391	(7,096)
Interest expense, net	(148)	(824)	(2,985)
Other (expense) income, net	(4,700)	5,383	(1,767)
Income (loss) from continuing operations before income taxes	24,992	33,950	(11,848)
(Provision for) benefit from income taxes	(3,982)	(15,872)	42,782
Income from continuing operations	21,010	18,078	30,934
Discontinued operations, net of tax:
(Loss) income from discontinued operations		(4,634)	5,851
Income on sale of discontinued operations			2,000
Total discontinued operations		(4,634)	7,851
NET INCOME	21,010	13,444	38,785
Net income attributable to noncontrolling interests	(2,226)	(1,837)	(137)
NET INCOME ATTRIBUTABLE TO IDT CORPORATION	18,784	11,607	38,648
Amounts attributable to IDT Corporation common stockholders:
Income from continuing operations	18,784	16,048	29,901
(Loss) income from discontinued operations		(4,441)	8,747
NET INCOME ATTRIBUTABLE TO IDT CORPORATION	18,784	11,607	38,648
Basic:
Income from continuing operations	$ 0.85	$ 0.85	$ 1.45
(Loss) income from discontinued operations		$ (0.21)	$ 0.42
Net income	$ 0.85	$ 0.85	$ 1.87
Weighted-average number of shares used in calculation of basic earnings per share	22,009	20,876	20,717
Diluted:
Income from continuing operations	$ 0.82	$ 0.82	$ 1.36
(Loss) income from discontinued operations		$ (0.20)	$ 0.39
Net income	$ 0.82	$ 0.82	$ 1.75
Weighted-average number of shares used in calculation of diluted earnings per share	22,937	22,315	22,060
(i) Stock-based compensation included in selling, general and administrative expenses	$ 5,382	$ 5,875	$ 3,325