Consolidated Statements Of Operations - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Aug. 31, 2016	Aug. 31, 2015	Aug. 31, 2014
Consolidated Statements Of Operations [Abstract]
Operating revenues	$ 516,411	$ 560,181	$ 617,933
Cost of operating revenues	367,798	403,860	446,938
Gross profit	148,613	156,321	170,995
Operating expenses:
Selling expense	41,973	40,516	38,284
General and administrative expense	56,419	52,261	43,228
Engineering and research expense	15,846	12,849	11,125
Total operating expenses	114,238	105,626	92,637
Operating income	34,375	50,695	78,358
Interest expense	(4,751)	(2,626)	(187)
Interest income	645	631	729
Other expense, net	(981)	(1,949)	(245)
Earnings before income taxes	29,288	46,751	78,655
Income tax expense	9,021	20,442	27,143
Net earnings	$ 20,267	$ 26,309	$ 51,512
Earnings per share:
Basic	$ 1.86	$ 2.23	$ 4.01
Diluted	$ 1.85	$ 2.22	$ 4.00
Shares used in computing earnings per share:
Basic	10,906	11,818	12,832
Diluted	10,930	11,855	12,882
Cash dividends declared per share	$ 1.13	$ 1.09	$ 0.92