Condensed Consolidated Statements of Shareholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Treasury Stock [Member]	Capital In Excess Of Stated Value [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Loss, Net [Member]
Beginning balance, value at Aug. 31, 2021	$ 338,445	$ 18,991	$ (277,238)	$ 86,495	$ 528,130	$ (17,933)
Beginning balance, shares at Aug. 31, 2021		18,991	8,083
Net earnings	47,540	$ 0	$ 0	0	47,540	0
Other comprehensive income (loss)	(443)	0	0	0	0	(443)
Total comprehensive income	47,097	0	0	0	0	0
Cash dividends per share	(10,865)	0	0	0	(10,865)	0
Issuance of common shares under share compensation plans, net	2,032	$ 72	$ 0	1,960	0	0
Issuance of common shares under share compensation plans, net, shares		72	0
Share-based compensation expense	4,061	$ 0	$ 0	4,061	0	0
Ending balance, value at May. 31, 2022	380,770	$ 19,063	$ (277,238)	92,516	564,805	(18,376)
Ending Balance, shares at May. 31, 2022		19,063	8,083
Beginning balance, value at Feb. 28, 2022	356,538	$ 19,061	$ (277,238)	90,711	543,355	(19,351)
Beginning balance, shares at Feb. 28, 2022		19,061	8,083
Net earnings	25,073	$ 0	$ 0	0	25,073	0
Other comprehensive income (loss)	975	0	0	0	0	975
Total comprehensive income	26,048	0	0	0	0	0
Cash dividends per share	(3,623)	0	0	0	(3,623)	0
Issuance of common shares under share compensation plans, net	157	$ 2	$ 0	155	0	0
Issuance of common shares under share compensation plans, net, shares		2	0
Share-based compensation expense	1,650	$ 0	$ 0	1,650	0	0
Ending balance, value at May. 31, 2022	380,770	$ 19,063	$ (277,238)	92,516	564,805	(18,376)
Ending Balance, shares at May. 31, 2022		19,063	8,083
Beginning balance, value at Aug. 31, 2022	393,358	$ 19,063	$ (277,238)	94,006	579,000	(21,473)
Beginning balance, shares at Aug. 31, 2022		19,063	8,083
Net earnings	53,150	$ 0	$ 0	0	53,150	0
Other comprehensive income (loss)	(1,134)	0	0	0	0	(1,134)
Total comprehensive income	52,016	0	0	0	0	0
Cash dividends per share	(11,228)	0	0	0	(11,228)	0
Issuance of common shares under share compensation plans, net	(2,125)	$ 29	$ 0	(2,154)	0	0
Issuance of common shares under share compensation plans, net, shares		29	0
Share-based compensation expense	4,775	$ 0	$ 0	4,775	0	0
Ending balance, value at May. 31, 2023	436,796	$ 19,092	$ (277,238)	96,627	620,922	(22,607)
Ending Balance, shares at May. 31, 2023		19,092	8,083
Beginning balance, value at Feb. 28, 2023	422,272	$ 19,091	$ (277,238)	94,834	607,784	(22,199)
Beginning balance, shares at Feb. 28, 2023		19,091	8,083
Net earnings	16,881	$ 0	$ 0	0	16,881	0
Other comprehensive income (loss)	(408)	0	0	0	0	(408)
Total comprehensive income	16,473	0	0	0	0	0
Cash dividends per share	(3,743)	0	0	0	(3,743)	0
Issuance of common shares under share compensation plans, net	107	$ 1	$ 0	106	0	0
Issuance of common shares under share compensation plans, net, shares		1	0
Share-based compensation expense	1,687	$ 0	$ 0	1,687	0	0
Ending balance, value at May. 31, 2023	$ 436,796	$ 19,092	$ (277,238)	$ 96,627	$ 620,922	$ (22,607)
Ending Balance, shares at May. 31, 2023		19,092	8,083