LEASES Rental Expense for all operating leases (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Jul. 31, 2012	Jul. 31, 2011	Jul. 31, 2010
Total Rental Expense
Rent Expense, Net	$ 3,695	$ 3,238	$ 3,296
Vehicles and Railcars
Total Rental Expense
Rent Expense	2,029	1,574	1,536
Office Facilities
Total Rental Expense
Rent Expense	848	840	809
Warehouse Facilities
Total Rental Expense
Rent Expense	252	288	335
Mining Properties
Total Rental Expense
Rent Expense, Minimum	123	112	113
Rent Expense, Contingent	302	289	336
Other
Total Rental Expense
Rent Expense	$ 141	$ 135	$ 167