Property, Plant And Equipment (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Aug. 31, 2012	Aug. 31, 2011	Aug. 31, 2010
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	$ 115,293	$ 109,694
Accumulated depreciation	(70,596)	(65,083)
Total operating property, plant and equipment, net	44,697	44,611
Machines	3,945	3,907
Barriers	17,457	18,198
Total property held for lease	21,402	22,105
Accumulated depreciation	(9,919)	(8,251)
Total property held for lease, net	11,483	13,854
Property, plant and equipment, net	56,180	58,465
Depreciation expense	9,600	9,000	8,100
Land [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	2,541	2,859
Building [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	28,652	29,372
Equipment [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	75,097	71,942
Other Capitalized Property Plant and Equipment [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	$ 9,003	$ 5,521