Property, Plant And Equipment (Details) - USD ($) $ in Thousands	12 Months Ended
	Aug. 31, 2017	Aug. 31, 2016	Aug. 31, 2015
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	$ 162,839	$ 159,522
Accumulated depreciation	(99,912)	(90,210)
Total operating property, plant and equipment, net	62,927	69,312
Machines	7,833	6,868
Barriers	18,468	16,306
Total property held for lease	26,301	23,174
Accumulated depreciation	(14,730)	(14,859)
Total property held for lease, net	11,571	8,315
Property, plant and equipment, net	74,498	77,627
Depreciation expense	12,200	12,200	$ 11,700
Land [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	4,869	4,817
Building [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	49,977	48,417
Machinery And Equipment [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	80,442	73,185
Furniture and Fixtures [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	24,547	24,787
Construction in Progress [Member]
Property, Plant and Equipment [Line Items]
Total operating property, plant and equipment	$ 3,004	$ 8,316