Severance Expense (Details) - USD ($) $ in Thousands	2 Months Ended	3 Months Ended		12 Months Ended
	Mar. 31, 2015	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Severance Expense (Textual)
Severance expense		$ 6,300	$ 200		$ 6,510	$ 8,363
Accrued severance		100			100
IDT Telecom [Member]
Severance Expense (Textual)
Severance expense						$ 1,900
Workforce reduction [Member]
Severance Expense (Textual)
Severance expense	$ 6,200
Accrued severance		$ 5,700		$ 300	5,700
Unrelated to workforce reduction [Member]
Severance Expense (Textual)
Severance expense					$ 200