Marketable Securities (Details Textual) - USD ($)	3 Months Ended		9 Months Ended
	Apr. 30, 2018	Apr. 30, 2017	Apr. 30, 2018	Apr. 30, 2017	Jul. 31, 2017
Marketable Securities (Textual)
Proceeds from maturities and sales of available-for-sale securities	$ 5,000,000	$ 14,000,000	$ 36,700,000	$ 30,800,000
Gross realized gains		$ 26,000		$ 300,000
Gross realized losses	$ (7,000)		$ (16,000)
Zedge [Member]
Marketable Securities (Textual)
Shares owned	24,923		24,923		23,227
Fair value of common stock	$ 100,000		$ 100,000		$ 48,000