Marketable Securities (Details Textual) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2015	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Marketable Securities (Textual)
Shares received Zedge Class B common stock				64,624
Amount paid for Straight Path Class B common stock received				$ 2.1
Proceeds from maturities and sales of available-for-sale securities		$ 48.0	$ 35.0	24.1
Realized gains from sales of available-for-sale securities	$ 0.5	0.3	0.5
Realized losses from sales of available-for-sale securities				$ 0.1
Unrealized losses, less than twelve months or longer