Concentration of Customers and Gain on Sale of Rights in Wireless Spectrum (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended	6 Months Ended
Jan. 31, 2014	Jan. 31, 2013	Jan. 31, 2014	Jan. 31, 2013
Revenues	$ 453	$ 229	$ 580	$ 697
Straight Path Spectrum [Member]
Revenues	109	136	216	277
AT&T[Member] \| Straight Path Spectrum [Member]
Revenues			59
TelePacific Communications [Member] \| Straight Path Spectrum [Member]
Revenues			$ 83	$ 83

Amount of revenue recognized from goods sold, services rendered, insurance premiums, or other activities that constitute an earning process. Includes, but is not limited to, investment and interest income before deduction of interest expense when recognized as a component of revenue, and sales and trading gain (loss).

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 225

-SubTopic 10

-Section S99

-Paragraph 2

-Subparagraph (SX 210.5-03.1)

-URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 1

-Article 5

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration