Basis of Presentation (Details) In Thousands, unless otherwise specified	9 Months Ended
	Apr. 30, 2015	Jul. 31, 2014	Jul. 31, 2013
Common Stock [Member] | Class A common stock [Member]
Basis of Presentation (Textual)
Common stock shares distributed	787	787	787
Common stock, shares outstanding	787	787
Common Stock [Member] | Class B common stock [Member]
Basis of Presentation (Textual)
Common stock shares distributed	11,226	11,013	10,700
Common stock, shares outstanding	11,184	11,013
Straight Path Spectrum [Member]
Basis of Presentation (Textual)
Ownership in straight path spectrum	100.00%
Straight Path IP [Member]
Basis of Presentation (Textual)
Ownership in straight path spectrum	84.50%
IDT [Member] | Class B common stock [Member]
Basis of Presentation (Textual)
Common stock, shares outstanding			21,400