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, 2020	$ 298,518	$ 18,918	$ (277,238)	$ 77,686	$ 499,724	$ (20,572)
Beginning balance, shares at Aug. 31, 2020		18,918	8,083
Net earnings	36,768	$ 0	$ 0	0	36,768	0
Other comprehensive income (loss)	3,809	0	0	0	0	3,809
Total comprehensive income	40,577	0	0	0	0	0
Cash dividends per share	(10,566)	0	0	0	(10,566)	0
Issuance of common shares under share compensation plans, net	2,623	$ 73	$ 0	2,550	0	0
Issuance of common shares under share compensation plans, net, shares		73	0
Share-based compensation expense	5,021	$ 0	$ 0	5,021	0	0
Ending balance, value at May. 31, 2021	336,173	$ 18,991	$ (277,238)	85,257	525,926	(16,763)
Ending Balance, shares at May. 31, 2021		18,991	8,083
Beginning balance, value at Feb. 28, 2021	319,024	$ 18,990	$ (277,238)	84,206	511,728	(18,662)
Beginning balance, shares at Feb. 28, 2021		18,990	8,083
Net earnings	17,797	$ 0	$ 0	0	17,797	0
Other comprehensive income (loss)	1,899	0	0	0	0	1,899
Total comprehensive income	19,696	0	0	0	0	0
Cash dividends per share	(3,599)	0	0	0	(3,599)	0
Issuance of common shares under share compensation plans, net	78	$ 1	$ 0	77	0	0
Issuance of common shares under share compensation plans, net, shares		1	0
Share-based compensation expense	974	$ 0	$ 0	974	0	0
Ending balance, value at May. 31, 2021	336,173	$ 18,991	$ (277,238)	85,257	525,926	(16,763)
Ending Balance, shares at May. 31, 2021		18,991	8,083
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