Condensed Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	3 Months Ended
	Nov. 30, 2015	Nov. 30, 2014
Condensed Consolidated Statements Of Operations [Abstract]
Operating revenues	$ 121,622	$ 134,845
Cost of operating revenues	87,208	97,931
Gross profit	34,414	36,914
Operating expenses:
Selling expense	9,992	9,417
General and administrative expense	9,015	12,871
Engineering and research expense	3,659	2,724
Total operating expenses	22,666	25,012
Operating income	11,748	11,902
Other income (expense):
Interest expense	(1,196)	(71)
Interest income	164	172
Other expense, net	(320)	(342)
Earnings before income taxes	10,396	11,661
Income tax expense	3,452	4,093
Net earnings	$ 6,944	$ 7,568
Earnings per share:
Basic	$ 0.62	$ 0.62
Diluted	$ 0.62	$ 0.62
Shares used in computing earnings per share:
Basic	11,259	12,224
Diluted	11,288	12,274
Cash dividends declared per share	$ 0.280	$ 0.270