Condensed Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Nov. 30, 2016	Nov. 30, 2015
Condensed Consolidated Statements Of Operations [Abstract]
Operating revenues	$ 110,390	$ 121,622
Cost of operating revenues	82,016	87,208
Gross profit	28,374	34,414
Operating expenses:
Selling expense	9,982	9,992
General and administrative expense	11,355	9,015
Engineering and research expense	4,302	3,659
Total operating expenses	25,639	22,666
Operating income	2,735	11,748
Other income (expense):
Interest expense	(1,209)	(1,196)
Interest income	165	164
Other expense, net	(356)	(320)
Earnings before income taxes	1,335	10,396
Income tax expense	462	3,452
Net earnings	$ 873	$ 6,944
Earnings per share:
Basic	$ 0.08	$ 0.62
Diluted	$ 0.08	$ 0.62
Shares used in computing earnings per share:
Basic	10,638	11,259
Diluted	10,666	11,288
Cash dividends declared per share	$ 0.29	$ 0.28