Concentration of Customers (Details) - Straight Path Spectrum [Member] - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2016	Oct. 31, 2015
Customer 1 [Member]
Concentration Risk [Line Items]
Revenue	$ 48	$ 41
Customer 2 [Member]
Concentration Risk [Line Items]
Revenue	41	21
Customer 3 [Member]
Concentration Risk [Line Items]
Revenue	21	15
Customer 4 [Member]
Concentration Risk [Line Items]
Revenue	$ 16		[1]

[1] below 10%