Marketable Securities (Details Textual) - USD ($)	3 Months Ended		6 Months Ended
	Jan. 31, 2018	Jan. 31, 2017	Jan. 31, 2018	Jan. 31, 2017	Jul. 31, 2017
Marketable Securities (Textual)
Proceeds from maturities and sales of available-for-sale securities	$ 12,100,000	$ 10,800,000	$ 31,600,000	$ 16,800,000
Unrealized losses, less than twelve months or longer	14,000		14,000
Gross realized gains		$ 300,000		$ 300,000
Gross realized losses	$ (16,000)		$ (9,000)
Zedge [Member]
Marketable Securities (Textual)
Shares	24,923		24,923		23,227
Shares owned fair value	$ 76,000		$ 76,000		$ 48,000