Basis of Presentation (Details Textual) In Thousands, unless otherwise specified					6 Months Ended
	Jan. 31, 2014 Common Stock [Member] Common Class A [Member]	Jul. 31, 2013 Common Stock [Member] Common Class A [Member]	Jan. 31, 2014 Common Stock [Member] Common Class B [Member]	Jul. 31, 2013 Common Stock [Member] Common Class B [Member]	Jan. 31, 2014 Straight Path Spectrum [Member]	Jan. 31, 2014 Straight Path IP [Member]	Jul. 31, 2013 Idt [Member] Common Class A [Member]	Jul. 31, 2013 Idt [Member] Common Class B [Member]
Description of Business and Summary of Significant Accounting Policies (Textual)
Ownership in Straight Path Spectrum					100.00%	84.50%
Common stock shares distributed	787	787	11,008	10,693
Common stock, shares outstanding	787	787	11,008	10,693			1,600	21,400