Description of Business and Summary of Significant Accounting Policies (Details Textual) - USD ($) shares in Thousands	1 Months Ended	12 Months Ended
	Oct. 31, 2010	Jul. 31, 2015	Jul. 31, 2014	Jul. 31, 2013
Description of Business and Summary of Significant Accounting Policies (Textual)
Common stock shares distributed		60,000
Common Stock [Member] | Common Class A [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Common stock shares distributed		787	787	787
Common stock shares outstanding		787	787
Common Stock [Member] | Common Class B [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Common stock shares distributed		11,308	11,013	10,700
Common stock shares outstanding		11,266	11,013
Straight Path Spectrum [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Ownership in Straight Path Spectrum		100.00%
Renewal of 39 GHz FCC licenses	$ 210,000
License patent expiration date	Oct. 18, 2020
Description of License	The Company included the license renewal costs in other assets, which are being charged to expense on a straight-line basis over the ten-year term of the licenses.
Straight Path IP Group [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Ownership in Straight Path Spectrum		84.50%
Settlement of litigation, description		Straight Path IP Group generally pays law firms that represent it in litigation against alleged infringers of its intellectual property rights a percentage of the amounts recovered ranging from 0% to 40% depending on several factors.
Idt [Member] | Common Class B [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Common stock shares outstanding				21,400