Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Aug. 31, 2024	Aug. 31, 2023	Aug. 31, 2022
Income Statement [Abstract]
Operating revenues	$ 607,074	$ 674,084	$ 770,743
Cost of operating revenues	416,019	461,069	571,565
Gross profit	191,055	213,015	199,178
Operating expenses:
Selling expense	39,905	36,201	33,920
General and administrative expense	57,419	56,412	55,470
Engineering and research expense	17,123	18,218	15,145
Total operating expenses	114,447	110,831	104,535
Operating income	76,608	102,184	94,643
Other income (expense):
Interest expense	(3,234)	(3,788)	(4,269)
Interest income	5,189	2,783	622
Other income (expense), net	487	(804)	(3,128)
Total other income (expense)	2,442	(1,809)	(6,775)
Earnings before income taxes	79,050	100,375	87,868
Income tax expense	12,793	27,996	22,399
Net earnings	$ 66,257	$ 72,379	$ 65,469
Earnings per share:
Basic	$ 6.04	$ 6.58	$ 5.97
Diluted	$ 6.01	$ 6.54	$ 5.94
Shares used in computing earnings per share:
Basic	10,976	11,003	10,965
Diluted	11,017	11,062	11,031
Cash dividends declared per share	$ 1.41	$ 1.37	$ 1.33