LEASES Rental Expense for all operating leases (Details) - USD ($) $ in Thousands	12 Months Ended
	Jul. 31, 2018	Jul. 31, 2017
Total Rental Expense
Rent Expense, Total	$ 3,203	$ 3,151
Vehicles and Railcars
Total Rental Expense
Rent Expense	1,404	1,431
Office facilities
Total Rental Expense
Rent Expense	985	959
Warehouse facilities
Total Rental Expense
Rent Expense	408	379
Mining properties
Total Rental Expense
Rent Expense, Minimum	106	113
Rent Expense, Contingent	208	191
Other
Total Rental Expense
Rent Expense	$ 92	$ 78