Other Operating Gains (Losses), Net - Summary of Other Operating Gains (Losses), Net by Business Segment (Parenthetical) (Detail) (USD $)	0 Months Ended	1 Months Ended	3 Months Ended	12 Months Ended
	Jan. 17, 2012	Oct. 13, 2011	Apr. 30, 2013	Jul. 31, 2014		Jul. 31, 2013		Jul. 31, 2012
Other Operating Gains Loss Net Textual [Abstract]
Payment for settlement of disputes to T-Mobile		$ 10,000,000
Payment received on bankruptcy settlement	1,800,000
Legal fees incurred with T-Mobile								1,000,000
Proceeds from insurance				571,000
Loss on settlement of outstanding claims and disputes			9,600,000		[1]		[1]	(11,022,000)	[1]
NEW JERSEY
Other Operating Gains Loss Net Textual [Abstract]
Gain on insurance claim				600,000
Proceeds from insurance				600,000
Former Chief Executive Officer of Straight Path Spectrum, Inc [Member]
Other Operating Gains Loss Net Textual [Abstract]
Loss on settlement of outstanding claims and disputes				$ 100,000

[1] On October 12, 2011, the Company entered into a binding term sheet with T-Mobile USA, Inc. ("T-Mobile") to settle litigation related to an alleged breach of a wholesale supply agreement. In consideration of the settlement of all disputes between the parties, on October 13, 2011, the Company paid T-Mobile $10 million. The Company incurred legal fees of $1.0 million in fiscal 2012 in connection with this matter.