Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands		Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance (in shares) at Aug. 31, 2017		51,845,132		12,822,100
Balance at Aug. 31, 2017		$ 518	$ 741,748	$ (1,606,678)	$ 1,458,823	$ (34,720)	$ 559,691
Net income					123,516		123,516
Other comprehensive (loss) income						16,122	16,122
Common stock issued for employee stock plans (in shares)		479,871
Common stock issued for employee stock plans		$ 5	54,943				54,948
Vesting of restricted stock (in shares)		14,839		5,563
Vesting of restricted stock				$ (1,015)			$ (1,015)
Repurchases of common stock (in shares)				585,026			584,920
Repurchases of common stock				$ (112,892)			$ (112,892)
Stock-based compensation expense			15,420				15,420
Dividends declared					(43,700)		(43,700)
Retirement of Treasury Shares (in shares)		(13,292,689)		(13,292,689)
Retirement of Treasury Shares		$ (133)	(186,717)	$ 1,697,206	(1,510,355)
Balance (in shares) at Feb. 28, 2018		39,047,153		120,000
Balance at Feb. 28, 2018		$ 390	625,394	$ (23,379)	28,283	(18,598)	612,090
Balance (in shares) at Nov. 30, 2017		52,101,426		12,991,346
Balance at Nov. 30, 2017		$ 521	775,509	$ (1,638,384)	1,507,301	(26,730)	618,217
Net income					53,137		53,137
Other comprehensive (loss) income						8,132	8,132
Common stock issued for employee stock plans (in shares)		234,855
Common stock issued for employee stock plans		$ 2	28,664				28,666
Vesting of restricted stock (in shares)		3,561		1,343
Vesting of restricted stock				$ (263)			$ (263)
Repurchases of common stock (in shares)				420,000			420,000
Repurchases of common stock				$ (81,938)			$ (81,938)
Stock-based compensation expense			7,938				7,938
Dividends declared					(21,799)		(21,799)
Retirement of Treasury Shares (in shares)		(13,292,689)		(13,292,689)
Retirement of Treasury Shares		$ (133)	(186,717)	$ 1,697,206	(1,510,356)
Balance (in shares) at Feb. 28, 2018		39,047,153		120,000
Balance at Feb. 28, 2018		$ 390	625,394	$ (23,379)	28,283	(18,598)	612,090
Balance (in shares) at Aug. 31, 2018		39,264,849		1,072,263
Balance at Aug. 31, 2018		$ 393	667,531	$ (213,428)	122,843	(51,439)	525,900
Net income					168,998		168,998
Other comprehensive (loss) income						(2,913)	(2,913)
Common stock issued for employee stock plans (in shares)		349,846
Common stock issued for employee stock plans		$ 4	48,867				48,871
Vesting of restricted stock (in shares)		75,530		27,852
Vesting of restricted stock				$ (6,155)			$ (6,155)
Repurchases of common stock (in shares)				489,945			489,945
Repurchases of common stock				$ (104,584)			$ (104,584)
Stock-based compensation expense			16,140				16,140
Dividends declared					(48,756)		(48,756)
Cumulative effect of adoption of accounting standards*	[1]				1,303	717	2,020
Balance (in shares) at Feb. 28, 2019		39,690,225		1,590,060
Balance at Feb. 28, 2019		$ 397	732,538	$ (324,167)	244,388	(53,635)	599,521
Balance (in shares) at Nov. 30, 2018		39,447,491		1,366,613
Balance at Nov. 30, 2018		$ 394	694,078	$ (278,146)	184,071	(59,188)	541,209
Net income					84,702		84,702
Other comprehensive (loss) income						5,553	5,553
Common stock issued for employee stock plans (in shares)		219,815
Common stock issued for employee stock plans		$ 3	30,755				30,758
Vesting of restricted stock (in shares)		22,919		8,502
Vesting of restricted stock				$ (1,878)			$ (1,878)
Repurchases of common stock (in shares)				214,945			214,945
Repurchases of common stock				$ (44,143)			$ (44,143)
Stock-based compensation expense			7,705				7,705
Dividends declared					(24,385)		(24,385)
Balance (in shares) at Feb. 28, 2019		39,690,225		1,590,060
Balance at Feb. 28, 2019		$ 397	$ 732,538	$ (324,167)	$ 244,388	$ (53,635)	$ 599,521

[1] Includes the cumulative effect of adoption of accounting standards primarily due to both the adoption of the new revenue recognition standard (ASC 606) resulting in a cumulative increase to retained earnings related to certain fulfillment costs and the accounting standard update related to the U.S. Tax Cuts and Jobs Act ("TCJA") providing for the reclassification from accumulated other comprehensive loss to retained earnings for stranded tax effects. See Notes 3 and 4 for additional information.