Stockholder's Equity (Details 1) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2020	Jul. 31, 2019	Jul. 31, 2018
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based payment compensation	$ 23,322	$ 23,445	$ 23,221
General and administrative
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based payment compensation	17,567	18,254	19,351
Yard operations
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Stock-based payment compensation	$ 5,755	$ 5,191	$ 3,870