Property, Plant And Equipment (Details) - USD ($) $ in Thousands	Aug. 31, 2018	Aug. 31, 2017
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	$ 145,114	$ 162,839
Accumulated depreciation	(98,191)	(99,912)
Total operating property, plant, and equipment, net	46,923	62,927
Machines	8,214	7,833
Barriers	18,122	18,468
Total property held for lease	26,336	26,301
Accumulated depreciation	(16,011)	(14,730)
Total property held for lease, net	10,325	11,571
Property, plant, and equipment, net	57,248	74,498
Land [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	2,799	4,869
Building [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	37,220	49,977
Machinery And Equipment [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	75,635	80,442
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	22,727	24,547
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	$ 6,733	$ 3,004