Accumulated Other Comprehensive Income - Schedule of Accumulated Balances for Each Classification of Other Comprehensive Income (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Jul. 31, 2014	Jul. 31, 2013	Jul. 31, 2012
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	$ 2,341	$ 202	$ 3,027
Genie Spin-Off			(438)
Other comprehensive income attributable to IDT Corporation	1,327	2,139	(2,387)
Ending balance	3,668	2,341	202
Unrealized Gain (Loss) on Available-for-Sale Securities [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance			(4)
Genie Spin-Off
Other comprehensive income attributable to IDT Corporation	(8)		4
Ending balance	(8)
Foreign Currency Translation [Member]
Accumulated Other Comprehensive Income (Loss) [Line Items]
Beginning balance	2,341	202	3,031
Genie Spin-Off			(438)
Other comprehensive income attributable to IDT Corporation	1,335	2,139	(2,391)
Ending balance	$ 3,676	$ 2,341	$ 202

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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