Consolidated Statements of Earnings - USD ($) shares in Thousands, $ in Thousands	12 Months Ended
	Aug. 31, 2022	Aug. 31, 2021	Aug. 31, 2020
Income Statement [Abstract]
Operating revenues	$ 770,743	$ 567,646	$ 474,692
Cost of operating revenues	571,565	417,441	322,149
Gross profit	199,178	150,205	152,543
Operating expenses:
Selling expense	33,920	30,816	31,444
General and administrative expense	55,470	51,923	52,947
Engineering and research expense	15,145	13,359	13,950
Total operating expenses	104,535	96,098	98,341
Operating income	94,643	54,107	54,202
Other (expense) income:
Interest expense	(4,269)	(4,751)	(4,759)
Interest income	622	1,083	1,956
Other expense, net	(3,128)	(53)	(2,556)
Total other (expense) income	(6,775)	(3,721)	(5,359)
Earnings before income taxes	87,868	50,386	48,843
Income tax expense	22,399	7,814	10,214
Net earnings	$ 65,469	$ 42,572	$ 38,629
Earnings per share:
Basic	$ 5.97	$ 3.91	$ 3.57
Diluted	$ 5.94	$ 3.88	$ 3.56
Shares used in computing earnings per share:
Basic	10,965	10,886	10,823
Diluted	11,031	10,985	10,861
Cash dividends declared per share	$ 1.33	$ 1.30	$ 1.26