CONDENSED CONSOLIDATED STATEMENTS OF SHAREHOLDERS' EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Treasury Stock [Member]	Total
Beginning balance at Aug. 31, 2019	$ 20	$ 155,132	$ 374,060	$ (32,482)	$ (351,255)	$ 145,475
Beginning balance, shares at Aug. 31, 2019	19,773,977				6,055,316
Issuance of common stock under share-based compensation plan, net of shares withheld for taxes		(2,640)				(2,640)
Issuance of common stock under share-based compensation plan, net of shares withheld for taxes, shares	22,342
Stock-based compensation		2,214				2,214
Cash dividends			(8,406)			(8,406)
Acquisition of treasury stock					$ (4,957)	(4,957)
Acquisition of treasury stock, shares					26,800
Foreign currency translation adjustment				2,112		2,112
Net income			12,194			12,194
Ending balance at Nov. 30, 2019	$ 20	154,706	377,848	(30,370)	$ (356,212)	145,992
Ending balance, shares at Nov. 30, 2019	19,796,319				6,082,116
Beginning balance at Aug. 31, 2019	$ 20	155,132	374,060	(32,482)	$ (351,255)	145,475
Beginning balance, shares at Aug. 31, 2019	19,773,977				6,055,316
Foreign currency translation adjustment						159
Net income						41,045
Ending balance at May. 31, 2020	$ 20	157,101	388,265	(32,323)	$ (368,080)	144,983
Ending balance, shares at May. 31, 2020	19,812,685				6,147,899
Beginning balance at Nov. 30, 2019	$ 20	154,706	377,848	(30,370)	$ (356,212)	145,992
Beginning balance, shares at Nov. 30, 2019	19,796,319				6,082,116
Issuance of common stock under share-based compensation plan, net of shares withheld for taxes, shares	16,366
Stock-based compensation		1,675				1,675
Cash dividends			(9,236)			(9,236)
Acquisition of treasury stock					$ (4,701)	(4,701)
Acquisition of treasury stock, shares					24,774
Foreign currency translation adjustment				(98)		(98)
Net income			14,327			14,327
Ending balance at Feb. 29, 2020	$ 20	156,381	382,939	(30,468)	$ (360,913)	147,959
Ending balance, shares at Feb. 29, 2020	19,812,685				6,106,890
Stock-based compensation		720				720
Cash dividends			(9,198)			(9,198)
Acquisition of treasury stock					$ (7,167)	(7,167)
Acquisition of treasury stock, shares					41,009
Foreign currency translation adjustment				(1,855)		(1,855)
Net income			14,524			14,524
Ending balance at May. 31, 2020	$ 20	157,101	388,265	(32,323)	$ (368,080)	144,983
Ending balance, shares at May. 31, 2020	19,812,685				6,147,899
Beginning balance at Aug. 31, 2020	$ 20	157,850	398,731	(28,208)	$ (368,080)	$ 160,313
Beginning balance, shares at Aug. 31, 2020	19,812,685				6,147,899	13,664,786
Issuance of common stock under share-based compensation plan, net of shares withheld for taxes		(3,490)				$ (3,490)
Issuance of common stock under share-based compensation plan, net of shares withheld for taxes, shares	23,417
Stock-based compensation		2,665				2,665
Cash dividends			(9,199)			(9,199)
Foreign currency translation adjustment				588		588
Net income			23,623			23,623
Ending balance at Nov. 30, 2020	$ 20	157,025	413,155	(27,620)	$ (368,080)	174,500
Ending balance, shares at Nov. 30, 2020	19,836,102				6,147,899
Beginning balance at Aug. 31, 2020	$ 20	157,850	398,731	(28,208)	$ (368,080)	$ 160,313
Beginning balance, shares at Aug. 31, 2020	19,812,685				6,147,899	13,664,786
Foreign currency translation adjustment						$ 4,430
Net income						61,820
Ending balance at May. 31, 2021	$ 20	162,240	432,230	(23,778)	$ (368,080)	$ 202,632
Ending balance, shares at May. 31, 2021	19,855,666				6,147,899	13,707,767
Beginning balance at Nov. 30, 2020	$ 20	157,025	413,155	(27,620)	$ (368,080)	$ 174,500
Beginning balance, shares at Nov. 30, 2020	19,836,102				6,147,899
Issuance of common stock under share-based compensation plan, net of shares withheld for taxes		(5)				(5)
Issuance of common stock under share-based compensation plan, net of shares withheld for taxes, shares	19,564
Stock-based compensation		1,877				1,877
Cash dividends			(9,217)			(9,217)
Foreign currency translation adjustment				3,234		3,234
Net income			17,191			17,191
Ending balance at Feb. 28, 2021	$ 20	158,897	421,129	(24,386)	$ (368,080)	187,580
Ending balance, shares at Feb. 28, 2021	19,855,666				6,147,899
Stock-based compensation		3,343				3,343
Cash dividends			(9,905)			(9,905)
Foreign currency translation adjustment				608		608
Net income			21,006			21,006
Ending balance at May. 31, 2021	$ 20	$ 162,240	$ 432,230	$ (23,778)	$ (368,080)	$ 202,632
Ending balance, shares at May. 31, 2021	19,855,666				6,147,899	13,707,767