NET PROPERTY AND EQUIPMENT HELD FOR LEASE: (Details) (USD $)	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
NET PROPERTY AND EQUIPMENT HELD FOR LEASE:
Depreciation expense	$ 11,400,000	$ 11,400,000	$ 11,200,000
Components of Net Property and Equipment Held for Lease
Less Accumulated Depreciation	(175,756,000)	(165,124,000)
Net Property and Equipment Held for Lease	84,095,000	92,824,000
Future minimum payments to be received under the lease
2013	21,500,000
2014	21,500,000
2015	21,500,000
2016	21,500,000
2017	21,500,000
Thereafter	7,167,000
Total	114,667,000
Land and Land Improvements
Components of Net Property and Equipment Held for Lease
Gross Property and Equipment Held for Lease	8,134,000	8,134,000
Buildings
Components of Net Property and Equipment Held for Lease
Gross Property and Equipment Held for Lease	41,767,000	41,655,000
Equipment
Components of Net Property and Equipment Held for Lease
Gross Property and Equipment Held for Lease	206,375,000	206,761,000
Construction in Progress
Components of Net Property and Equipment Held for Lease
Gross Property and Equipment Held for Lease	$ 3,575,000	$ 1,398,000