Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jan. 31, 2013	Jan. 31, 2012	Jan. 31, 2013	Jan. 31, 2012
Statements Of Operations [Abstract]
Revenues	$ 411,685	$ 365,449	$ 812,270	$ 742,226
Direct cost of revenues (exclusive of depreciation and amortization)	(344,499)	(306,365)	(679,763)	(625,717)
Gross profit	67,186	59,084	132,507	116,509
Operating expenses:
Selling, general and administrative (i)	56,399	51,552	111,625	103,335
Depreciation and amortization	3,865	4,231	7,000	8,673
Research and development	1,819	1,119	3,201	2,129
Total operating expenses	62,083	56,902	121,826	114,137
Other operating gains (losses), net	149	1,850	(201)	(9,402)
Income (loss) from operations	5,252	4,032	10,480	(7,030)
Interest expense, net	(455)	(1,350)	(346)	(1,828)
Other income (expense), net	1,815	(429)	2,700	(240)
Income (loss) from continuing operations before income taxes	6,612	2,253	12,834	(9,098)
(Provision for) benefit from income taxes	(3,117)	676	(5,171)	3,939
Income (loss) from continuing operations	3,495	2,929	7,663	(5,159)
Discontinued operations, net of tax:
Income from discontinued operations				1,015
Income on sale of discontinued operations				2,000
Total discontinued operations				3,015
Net income (loss)	3,495	2,929	7,663	(2,144)
Net (income) loss attributable to noncontrolling interests	(542)	(273)	(1,096)	474
Net income (loss) attributable to IDT Corporation	2,953	2,656	6,567	(1,670)
Amounts attributable to IDT Corporation common stockholders:
Income (loss) from continuing operations	2,953	2,656	6,567	(5,580)
Income from discontinued operations				3,910
Net income (loss)	2,953	2,656	6,567	(1,670)
Basic:
Income (loss) from continuing operations	$ 0.14	$ 0.13	$ 0.32	$ (0.27)
Income from discontinued operations				$ 0.19
Net income (loss)	$ 0.14	$ 0.13	$ 0.32	$ (0.08)
Weighted-average number of shares used in calculation of basic earnings per share	20,829	20,492	20,818	20,429
Diluted:
Income (loss) from continuing operations	$ 0.13	$ 0.12	$ 0.30	$ (0.27)
Income from discontinued operations				$ 0.19
Net income (loss)	$ 0.13	$ 0.12	$ 0.30	$ (0.08)
Weighted-average number of shares used in calculation of diluted earnings per share	22,089	21,811	22,087	20,429
Dividends declared per common share		$ 0.13	$ 0.75	$ 0.36
(i) Stock-based compensation included in selling, general and administrative expenses	$ 1,806	$ 932	$ 4,031	$ 1,616