Accumulated Other Comprehensive Income (Loss) - Schedule of Accumulated Balances for Each Classification of Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ 3,027
Other comprehensive income (loss) attributable to IDT Corporation	(2,268)	4,163	(1,824)
Ending balance	202	3,027
Unrealized Gain (Loss) On Available-For-Sale Securities [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(4)	(131)	180
Spin-Off
Other comprehensive income (loss) attributable to IDT Corporation	4	127	(311)
Ending balance		(4)	(131)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	3,031	(886)	773
Spin-Off	(438)		(177)
Other comprehensive income (loss) attributable to IDT Corporation	(2,391)	3,917	(1,482)
Ending balance	202	3,031	(886)
Accumulated Other Comprehensive Income (Loss) [Member]
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	3,027	(1,017)	953
Spin-Off	(438)		(177)
Other comprehensive income (loss) attributable to IDT Corporation	(2,387)	4,044	(1,793)
Ending balance	$ 202	$ 3,027	$ (1,017)