IDT Financial Services Ltd. Recent Transactions (Details) - IDT Financial Services Ltd. [Member] € in Millions, $ in Millions	9 Months Ended
	Apr. 30, 2016 USD ($)	Apr. 30, 2016 EUR (€)	Dec. 31, 2015 USD ($)
IDT Financial Services Ltd. Recent Transactions (Textual)
Security deposit			$ 4.7
Estimated adjustments to be received	$ 5.4	€ 4.7
Earn-out portion of consideration, Description	The cash consideration payable will be increased by 1.75 billion ($2.0 billion at April 30, 2016), of which 750 million ($859.0 million at April 30, 2016) will be payable upon closing and 1.0 billion ($1.1 billion at April 30, 2016), plus 4% compound annual interest, will be payable on the third anniversary of closing. The transaction remains subject to regulatory approval. The closing may extend beyond the end of the second quarter of calendar 2016.	The cash consideration payable will be increased by 1.75 billion ($2.0 billion at April 30, 2016), of which 750 million ($859.0 million at April 30, 2016) will be payable upon closing and 1.0 billion ($1.1 billion at April 30, 2016), plus 4% compound annual interest, will be payable on the third anniversary of closing. The transaction remains subject to regulatory approval. The closing may extend beyond the end of the second quarter of calendar 2016.
Additional total cash consideration to be received	$ 2,000.0	€ 1,750.0
Portion of additional total cash consideration to be received at closing	1,100.0	1,000.0
Portion of additional total cash consideration to be received on third anniversary of closing	859.0	750.0
Preferred stock [Member]
IDT Financial Services Ltd. Recent Transactions (Textual)
Estimated adjustments to be received	$ 1.9	€ 1.6