Defined Contributions and Other Postretirement Plans (Details Textual) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017	Jul. 31, 2016
Employee 401(k) Plan (Textual) [Abstract]
Maximum Annual Contribution Per Employee, Percent	60.00%
Maximum Annual Contribution Per Employee, Amount	$ 5
Company's contributions	$ 8,700	$ 7,100	$ 5,500