Business Segment Information (Details) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2017	Oct. 31, 2016
Summary of operating results for the business segments
Revenues	$ 165	$ 159
Loss from operations	(13,230)	(3,403)
Straight Path Spectrum [Member]
Summary of operating results for the business segments
Revenues	165	159
Loss from operations	(12,739)	(2,986)
Straight Path Ventures [Member]
Summary of operating results for the business segments
Revenues
Loss from operations	$ (491)	$ (417)