Revenues and Gain on Sale of Rights in Wireless Spectrum (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2013	Jul. 31, 2012
Summary of revenues and gain on sale
Revenues	$ 1,130	$ 553
Straight Path Spectrum [Member]
Summary of revenues and gain on sale
Revenues	525	553
Straight Path Spectrum [Member] | Covad Communications Group [Member]
Summary of revenues and gain on sale
Revenues	165	161
Straight Path Spectrum [Member] | AT&T[Member]
Summary of revenues and gain on sale
Revenues	134	124
Straight Path Spectrum [Member] | Verizon [Member]
Summary of revenues and gain on sale
Revenues		$ 90