Equity - Summary of Changes in Components of Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended
	Oct. 31, 2013	Oct. 31, 2012
Changes in the components of equity
Beginning Balance	$ 89,136
Restricted Class B common stock purchased from employee	(104)
Exercise of stock options	523
Purchase of stock of subsidiary	(1,133)
Adjustment to liabilities in connection with the Straight Path Spin-Off	(1,624)
Distributions to noncontrolling interests	(501)	(400)
Stock-based compensation	2,495	1,012
Comprehensive income:
Net income	4,050	4,168
Foreign currency translation adjustments	664	1,628
Comprehensive income	4,714	5,796
Ending Balance	93,506
Attributable to IDT Corporation [Member]
Changes in the components of equity
Beginning Balance	88,603
Restricted Class B common stock purchased from employee	(104)
Exercise of stock options	523
Purchase of stock of subsidiary	(1,154)
Adjustment to liabilities in connection with the Straight Path Spin-Off	(1,624)
Distributions to noncontrolling interests
Stock-based compensation	2,485
Comprehensive income:
Net income	3,523
Foreign currency translation adjustments	664
Comprehensive income	4,187
Ending Balance	92,916
Noncontrolling Interests [Member]
Changes in the components of equity
Beginning Balance	533
Restricted Class B common stock purchased from employee
Exercise of stock options
Purchase of stock of subsidiary	21
Adjustment to liabilities in connection with the Straight Path Spin-Off
Distributions to noncontrolling interests	(501)
Stock-based compensation	10
Comprehensive income:
Net income	527
Foreign currency translation adjustments
Comprehensive income	527
Ending Balance	$ 590