Marketable Securities (Details Textual) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
	Oct. 31, 2015	Jul. 31, 2016	Jul. 31, 2015	Jul. 31, 2014
Class of Stock [Line Items]
Proceeds from maturities and sales of available-for-sale securities		$ 35.0	$ 24.1	$ 17.3
Realized gains from sales of available-for-sale securities	$ 0.5	0.5
Realized losses from sales of available-for-sale securities			0.1
Other than temporary impairment losses, investments, available-for-sale securities				$ 0.1
Unrealized losses, less than twelve months or longer
Straight Path Class B shares [Member]
Class of Stock [Line Items]
Company received number of Straight Path Class B common stock, shares			64,624