Equity - Summary of Changes in Components of Equity (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Apr. 30, 2014	Apr. 30, 2013	Apr. 30, 2014	Apr. 30, 2013
Changes in the components of equity
Beginning Balance			$ 89,136
Dividends declared ($0.34 per share)			(7,850)
Restricted Class B common stock purchased from employees			(955)
Exercise of stock options			609
Stock issued for matching contributions to the 401(k) Plan			1,168
Purchase of stock of subsidiary			(1,133)
Adjustment to liabilities in connection with the Straight Path Spin-Off			(1,624)
Distributions to noncontrolling interests			(1,287)
Stock-based compensation	793	1,523	4,920	4,340
Comprehensive income:
Net income	5,599	9,124	12,622	16,787
Foreign currency translation adjustments	531	(1,892)	1,713	1,381
Comprehensive income	6,130	7,232	14,335	18,168
Ending Balance	97,319		97,319
Attributable to IDT Corporation [Member]
Changes in the components of equity
Beginning Balance			88,603
Dividends declared ($0.34 per share)			(7,850)
Restricted Class B common stock purchased from employees			(955)
Exercise of stock options			606
Stock issued for matching contributions to the 401(k) Plan			1,168
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			4,890
Comprehensive income:
Net income			11,074
Foreign currency translation adjustments			1,713
Comprehensive income			12,787
Ending Balance	96,471		96,471
Noncontrolling Interests [Member]
Changes in the components of equity
Beginning Balance			533
Dividends declared ($0.34 per share)
Restricted Class B common stock purchased from employees
Exercise of stock options			3
Stock issued for matching contributions to the 401(k) Plan
Purchase of stock of subsidiary			21
Adjustment to liabilities in connection with the Straight Path Spin-Off
Distributions to noncontrolling interests			(1,287)
Stock-based compensation			30
Comprehensive income:
Net income			1,548
Foreign currency translation adjustments
Comprehensive income			1,548
Ending Balance	$ 848		$ 848