Consolidated Statements of Changes In Stockholders' Equity - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	AOCI Attributable to Parent [Member]	Total
Balance, beginning of year at Aug. 31, 2015	$ 503	$ 542,355	$ (988,873)	$ 1,021,651	$ (44,052)	$ 531,584
Common stock issued for employee stock plans	9	57,784				57,793
Retirement of Treasury shares
Balance, end of year at Aug. 31, 2016	512	623,195	(1,321,700)	1,283,927	(68,553)	517,381
Stock-based compensation expense		29,793				29,793
Tax benefits from share-based payment arrangements		18,205				18,205
Accelerated share repurchase		(24,000)
Stock-based compensation adjustment associated with disposition		(942)				(942)
Repurchases of common stock			(328,283)			(352,283)
Accelerated share repurchase
Purchases of common stock upon restricted stock vesting			(4,544)			(4,544)
Net income				338,815		338,815
Dividends				(76,539)		(76,539)
Foreign currency translation adjustments					(23,644)	(23,644)
Net unrealized (loss) gain on cash flow hedges, net of tax					(857)	(857)	[1]
Common stock issued for employee stock plans	6	50,039				50,045
Retirement of Treasury shares
Balance, end of year at Aug. 31, 2017	518	741,748	(1,606,678)	1,458,823	(34,720)	559,691
Stock-based compensation expense		34,183				34,183
Tax benefits from share-based payment arrangements		10,331				10,331
Accelerated share repurchase		24,000
Stock-based compensation adjustment associated with disposition
Repurchases of common stock			(253,131)			(253,131)
Accelerated share repurchase			(24,000)
Purchases of common stock upon restricted stock vesting			(7,847)			(7,847)
Net income				258,259		258,259
Dividends				(83,363)		(83,363)
Foreign currency translation adjustments					28,816	28,816
Net unrealized (loss) gain on cash flow hedges, net of tax					5,017	5,017	[1]
Common stock issued for employee stock plans	8	80,983				80,992
Retirement of Treasury shares	(133)	(186,717)	1,697,205	(1,510,355)
Balance, end of year at Aug. 31, 2018	$ 393	667,531	(213,428)	122,843	(51,439)	525,900
Stock-based compensation expense		31,517				31,516
Tax benefits from share-based payment arrangements
Accelerated share repurchase
Stock-based compensation adjustment associated with disposition
Repurchases of common stock			(302,441)			(302,441)
Accelerated share repurchase
Purchases of common stock upon restricted stock vesting			$ (1,514)			(1,514)
Net income				267,085		267,085
Dividends				$ (92,710)		(92,710)
Foreign currency translation adjustments					(9,431)	(9,431)
Net unrealized (loss) gain on cash flow hedges, net of tax					$ (7,288)	$ (7,288)	[1]

[1] The unrealized gain (loss) on cash flow hedges disclosed above was net of tax benefit (expense) of $3,518, ($3,049) and $498 for the fiscal years ended August 31, 2018, 2017 and 2016, respectively.