Consolidated Statements of Operations (Unaudited) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Statements Of Operations [Abstract]
Revenues	$ 397,221	$ 379,719	$ 1,209,491	$ 1,121,945
Costs and expenses:
Direct cost of revenues (exclusive of depreciation and amortization)	331,178	319,811	1,010,941	945,528
Selling, general and administrative (i)	55,229	51,254	166,854	154,589
Depreciation and amortization	3,972	4,163	10,972	12,836
Research and development	1,717	1,191	4,918	3,320
Total costs and expenses	392,096	376,419	1,193,685	1,116,273
Other operating gains (losses), net	9,601	(1,138)	9,401	(10,540)
Income (loss) from operations	14,726	2,162	25,207	(4,868)
Interest expense, net	(443)	(434)	(790)	(2,262)
Other income (expense), net	2,433	(564)	5,133	(804)
Income (loss) from continuing operations before income taxes	16,716	1,164	29,550	(7,934)
(Provision for) benefit from income taxes	(7,592)	2,285	(12,763)	6,224
Income (loss) from continuing operations	9,124	3,449	16,787	(1,710)
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	9,124	3,449	16,787	1,305
Net (income) loss attributable to noncontrolling interests	(433)	(460)	(1,529)	14
Net income attributable to IDT Corporation	8,691	2,989	15,258	1,319
Amounts attributable to IDT Corporation common stockholders:
Income (loss) from continuing operations	8,691	2,989	15,258	(2,591)
Income from discontinued operations				3,910
Net income	8,691	2,989	15,258	1,319
Basic:
Income (loss) from continuing operations	$ 0.42	$ 0.14	$ 0.73	$ (0.13)
Income from discontinued operations				$ 0.19
Net income	$ 0.42	$ 0.14	$ 0.73	$ 0.06
Weighted-average number of shares used in calculation of basic earnings per share	20,905	21,041	20,847	20,633
Diluted:
Income (loss) from continuing operations	$ 0.39	$ 0.14	$ 0.69	$ (0.13)
Income from discontinued operations				$ 0.19
Net income	$ 0.39	$ 0.14	$ 0.69	$ 0.06
Weighted-average number of shares used in calculation of diluted earnings per share	22,360	22,084	22,178	20,633
Dividends declared per common share		$ 0.15	$ 0.75	$ 0.51
(i) Stock-based compensation included in selling, general and administrative expenses	$ 1,601	$ 1,007	$ 5,631	$ 2,623