Consolidated Statements of Changes in Stockholders' Equity - Unaudited - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Loss
Beginning balance (in shares) at Aug. 31, 2020		40,767,708		2,737,456
Beginning balance at Aug. 31, 2020	$ 896,375	$ 408	$ 939,067	$ (636,956)	$ 633,149	$ (39,293)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	101,206				101,206
Other comprehensive income (loss)	217					217
Common stock issued for employee stock plans (in shares)		98,459
Common stock issued for employee stock plans	17,992	$ 1	17,991
Vesting of restricted stock (in shares)		17,946		6,728
Vesting of restricted stock	$ (2,124)			$ (2,124)
Repurchase of common stock (in shares)	131,800			131,800
Repurchases of common stock	$ (43,144)			$ (43,144)
Stock-based compensation	11,317		11,317
Dividends declared	(29,266)				(29,266)
Ending balance (in shares) at Nov. 30, 2020		40,884,113		2,875,984
Ending balance at Nov. 30, 2020	952,573	$ 409	968,375	$ (682,224)	705,089	(39,076)
Beginning balance (in shares) at Aug. 31, 2021		41,163,192		3,547,773
Beginning balance at Aug. 31, 2021	1,016,353	$ 412	1,048,305	$ (905,917)	912,515	(38,962)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	107,647				107,647
Other comprehensive income (loss)	(18,708)					(18,708)
Common stock issued for employee stock plans (in shares)		192,349
Common stock issued for employee stock plans	35,763	$ 2	35,761
Vesting of restricted stock (in shares)		17,349		6,747
Vesting of restricted stock	$ (2,949)			$ (2,949)
Repurchase of common stock (in shares)	46,200			46,200
Repurchases of common stock	$ (18,639)			$ (18,639)
Stock-based compensation	10,401		10,401
Dividends declared	(30,973)				(30,973)
Ending balance (in shares) at Nov. 30, 2021		41,372,890		3,600,720
Ending balance at Nov. 30, 2021	$ 1,098,895	$ 414	$ 1,094,467	$ (927,505)	$ 989,189	$ (57,670)