Commitments and Contingencies (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Commitments and Contingencies (Textual)
Purchase commitment of company	$ 1,600
Rental expense under operating leases	3,200	$ 6,100	$ 6,400
Connectivity charges under operating leases	7,500	8,400	$ 10,400
Letters of credit outstanding	100
Performance bonds outstanding	13,400
Refundable customer deposits	95,843	84,454
IDT Financial Services [Member]
Commitments and Contingencies (Textual)
Refundable customer deposits	95,800	84,500
IDT Payment Services and IDT Financial Services [Member]
Commitments and Contingencies (Textual)
Restricted cash and cash equivalents	$ 16,000	$ 7,500
Expire on July 31, 2017 [Member]
Commitments and Contingencies (Textual)
Letters of credit expiration date	Jul. 31, 2017