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	18,971	$ 0	$ 0	0	18,971	0
Other comprehensive income (loss)	1,910	0	0	0	0	1,910
Total comprehensive income	20,881	0	0	0	0	0
Cash dividends per share	(6,967)	0	0	0	(6,967)	0
Issuance of common shares under share compensation plans, net	2,545	$ 72	$ 0	2,473	0	0
Issuance of common shares under share compensation plans, net, shares		72	0
Share-based compensation expense	4,047	$ 0	$ 0	4,047	0	0
Ending balance, value at Feb. 28, 2021	319,024	$ 18,990	$ (277,238)	84,206	511,728	(18,662)
Ending Balance, shares at Feb. 28, 2021		18,990	8,083
Beginning balance, value at Nov. 30, 2020	303,901	$ 18,948	$ (277,238)	78,026	503,342	(19,177)
Beginning balance, shares at Nov. 30, 2020		18,948	8,083
Net earnings	11,876	$ 0	$ 0	0	11,876	0
Other comprehensive income (loss)	515	0	0	0	0	515
Total comprehensive income	12,391	0	0	0	0	0
Cash dividends per share	(3,490)	0	0	0	(3,490)	0
Issuance of common shares under share compensation plans, net	3,758	$ 42	$ 0	3,716	0	0
Issuance of common shares under share compensation plans, net, shares		42	0
Share-based compensation expense	2,464	$ 0	$ 0	2,464	0	0
Ending balance, value at Feb. 28, 2021	319,024	$ 18,990	$ (277,238)	84,206	511,728	(18,662)
Ending Balance, shares at Feb. 28, 2021		18,990	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	22,467	$ 0	$ 0	0	22,467	0
Other comprehensive income (loss)	(1,418)	0	0	0	0	(1,418)
Total comprehensive income	21,049	0	0	0	0	0
Cash dividends per share	(7,242)	0	0	0	(7,242)	0
Issuance of common shares under share compensation plans, net	1,875	$ 70	$ 0	1,805	0	0
Issuance of common shares under share compensation plans, net, shares		70	0
Share-based compensation expense	2,411	$ 0	$ 0	2,411	0	0
Ending balance, value at Feb. 28, 2022	356,538	$ 19,061	$ (277,238)	90,711	543,355	(19,351)
Ending Balance, shares at Feb. 28, 2022		19,061	8,083
Beginning balance, value at Nov. 30, 2021	341,943	$ 19,056	$ (277,238)	89,006	532,410	(21,291)
Beginning balance, shares at Nov. 30, 2021		19,056	8,083
Net earnings	14,566	$ 0	$ 0	0	14,566	0
Other comprehensive income (loss)	1,940	0	0	0	0	1,940
Total comprehensive income	16,506	0	0	0	0	0
Cash dividends per share	(3,621)	0	0	0	(3,621)	0
Issuance of common shares under share compensation plans, net	521	$ 5	$ 0	516	0	0
Issuance of common shares under share compensation plans, net, shares		5	0
Share-based compensation expense	1,189	$ 0	$ 0	1,189	0	0
Ending balance, value at Feb. 28, 2022	$ 356,538	$ 19,061	$ (277,238)	$ 90,711	$ 543,355	$ (19,351)
Ending Balance, shares at Feb. 28, 2022		19,061	8,083