Equity (Details) (USD $) In Thousands, unless otherwise specified	1 Months Ended		3 Months Ended		9 Months Ended
	Dec. 31, 2012	Oct. 31, 2012	Apr. 30, 2013	Apr. 30, 2012	Apr. 30, 2013	Apr. 30, 2012
Changes in the components of equity
Beginning Balance					$ 102,725
Dividends declared ($0.75 per share)		(3,400)			(17,124)
Restricted Class B common stock purchased from employees					(300)
Repurchases of Class B common stock through repurchase program					(778)
Distributions to noncontrolling interests					(1,545)
Purchases of stock of subsidiary	1,800				(1,804)
Sale of stock of subsidiary					145
Stock-based compensation			1,601	1,007	5,631	2,623
Comprehensive income:
Net income			9,124	3,449	16,787	1,305
Foreign currency translation adjustments			(1,892)	1,933	1,381	(896)
Comprehensive income			7,232	5,382	18,168	413
Ending Balance			105,118		105,118
Attributable to IDT Corporation [Member]
Changes in the components of equity
Beginning Balance					102,230
Dividends declared ($0.75 per share)					(17,124)
Restricted Class B common stock purchased from employees					(300)
Repurchases of Class B common stock through repurchase program					(778)
Distributions to noncontrolling interests
Purchases of stock of subsidiary					(1,795)
Sale of stock of subsidiary					(58)
Stock-based compensation					5,363
Comprehensive income:
Net income					15,258
Foreign currency translation adjustments					1,428
Comprehensive income					16,686
Ending Balance			104,224		104,224
Noncontrolling Interests [Member]
Changes in the components of equity
Beginning Balance					495
Dividends declared ($0.75 per share)
Restricted Class B common stock purchased from employees
Repurchases of Class B common stock through repurchase program
Distributions to noncontrolling interests					(1,545)
Purchases of stock of subsidiary					(9)
Sale of stock of subsidiary					203
Stock-based compensation					268
Comprehensive income:
Net income					1,529
Foreign currency translation adjustments					(47)
Comprehensive income					1,482
Ending Balance			$ 894		$ 894