Business Segment Information (Details Textual) - Segment			9 Months Ended
	Feb. 01, 2016	Jan. 31, 2016	Apr. 30, 2017
Business Segment Information (Textual)
Reportable Segments			2
Straight Path IP Group [Member]
Business Segment Information (Textual)
Percentage of general and administrative expenses	20.00%	80.00%	20.00%
Employment expenses of Chief Technology Officer	20.00%
Straight Path Spectrum [Member]
Business Segment Information (Textual)
Percentage of general and administrative expenses	80.00%	20.00%
Employment expenses of Chief Technology Officer	20.00%
Employment expenses related to one employee	20.00%
Employee expenses related to several other employees	100.00%
Straight Path Ventures [Member]
Business Segment Information (Textual)
Percentage of general and administrative expenses	100.00%
Employment expenses of Chief Technology Officer	60.00%
Employment expenses related to one employee	80.00%