Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2023	May 31, 2022	May 31, 2023	May 31, 2022
Income Statement [Abstract]
Operating revenues	$ 164,553	$ 214,259	$ 506,953	$ 580,547
Cost of operating revenues	111,332	152,579	346,454	438,486
Gross profit	53,221	61,680	160,499	142,061
Operating expenses:
Selling expense	8,681	8,148	27,092	24,070
General and administrative expense	13,061	14,647	41,237	40,548
Engineering and research expense	4,522	3,723	13,350	10,582
Total operating expenses	26,264	26,518	81,679	75,200
Operating income	26,957	35,162	78,820	66,861
Other income (expense):
Interest expense	(948)	(1,006)	(2,895)	(3,345)
Interest income	680	118	1,545	456
Other income (expense), net	(957)	1,282	(2,000)	264
Total other income (expense)	(1,225)	394	(3,350)	(2,625)
Earnings before income taxes	25,732	35,556	75,470	64,236
Income tax expense	8,851	10,483	22,320	16,696
Net earnings	$ 16,881	$ 25,073	$ 53,150	$ 47,540
Earnings per share:
Basic	$ 1.53	$ 2.28	$ 4.83	$ 4.34
Diluted	$ 1.53	$ 2.28	$ 4.80	$ 4.31
Shares used in computing earnings per share:
Basic	11,008	10,978	11,001	10,960
Diluted	11,052	11,021	11,063	11,020
Cash dividends declared per share	$ 0.34	$ 0.33	$ 1.02	$ 0.99