Defined Contribution Plans (Details) - USD ($) shares in Thousands, $ in Millions	12 Months Ended
	Jul. 31, 2017	Jul. 31, 2016	Jul. 31, 2015
Defined Contribution Plans (Textual)
Maximum percentage of participants contribution	20.00%
Percentage of discretionary matching contributions	50.00%
Defined benefit plan compensation	6.00%
Company's cost for contributions to the plan	$ 1.2	$ 1.4	$ 1.3
Employment period contributions, description	First five years
401(k) Plan [Member]
Defined Contribution Plans (Textual)
Class B common stock to the plan for matching contributions		94,712	70,843