Stock-based Payment Compensation (Details 1) - USD ($) $ in Thousands	3 Months Ended
	Oct. 31, 2015	Oct. 31, 2014
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 5,414	$ 4,366
General and administrative [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	4,728	3,820
Yard Operations [Member]
Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items]
Total stock-based compensation	$ 686	$ 546