Revenues in Wireless Spectrum (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Jul. 31, 2015	Apr. 30, 2015	Jan. 31, 2015	Oct. 31, 2014	Jul. 31, 2014	Apr. 30, 2014	Jan. 31, 2014	Oct. 31, 2013	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Summary of revenues and gain on sale
Revenues	$ 2,769	$ 2,867	$ 2,781	$ 4,823	$ 3,303	$ 913	$ 453	$ 127	$ 13,240	$ 4,796	$ 1,130
Straight Path Spectrum [Member]
Summary of revenues and gain on sale
Revenues									426	424	525
Straight Path Spectrum [Member] | Customer 1 [Member]
Summary of revenues and gain on sale
Revenues									165	165	165
Straight Path Spectrum [Member] | Customer 2 [Member]
Summary of revenues and gain on sale
Revenues									87	114	$ 134
Straight Path Spectrum [Member] | Customer 3 [Member]
Summary of revenues and gain on sale
Revenues									$ 70	$ 53