Condensed Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	3 Months Ended		9 Months Ended
	May 31, 2022	May 31, 2021	May 31, 2022	May 31, 2021
Income Statement [Abstract]
Operating revenues	$ 214,259	$ 161,936	$ 580,547	$ 413,998
Cost of operating revenues	152,579	117,880	438,486	297,360
Gross profit	61,680	44,056	142,061	116,638
Operating expenses:
Selling expense	8,148	7,570	24,070	22,680
General and administrative expense	14,647	12,043	40,548	39,770
Engineering and research expense	3,723	3,102	10,582	9,504
Total operating expenses	26,518	22,715	75,200	71,954
Operating income	35,162	21,341	66,861	44,684
Other income (expense):
Interest expense	(1,006)	(1,178)	(3,345)	(3,584)
Interest income	118	227	456	798
Other income, net	1,282	764	264	699
Total other income (expense)	394	(187)	(2,625)	(2,087)
Earnings before income taxes	35,556	21,154	64,236	42,597
Income tax expense	10,483	3,357	16,696	5,829
Net earnings	$ 25,073	$ 17,797	$ 47,540	$ 36,768
Earnings per share:
Basic	$ 2.28	$ 1.63	$ 4.34	$ 3.38
Diluted	$ 2.28	$ 1.61	$ 4.31	$ 3.35
Shares used in computing earnings per share:
Basic	10,978	10,907	10,960	10,879
Diluted	11,021	11,033	11,020	10,967
Cash dividends declared per share	$ 0.33	$ 0.33	$ 0.99	$ 0.97