Consolidated Statements Of Stockholders' Equity (Deficit) - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock [Member]	Paid-In Capital [Member]	Retained Earnings [Member]	Treasury Stock [Member]
Stockholders' equity (deficit), beginning balance at Aug. 31, 2015	$ 17,433	$ 1,183	$ 232,550	$ 851,715	$ (1,068,015)
Beginning balance (in shares) at Aug. 31, 2015					67,249
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	64,067			64,067
Cash dividends	(21,340)			(21,340)
Stock-based compensation expense	3,766		3,766
Purchase of treasury stock	(148,345)				$ (148,345)
Purchase of treasury stock (in shares)					5,209
Exercise of stock options and issuance of restricted stock	3,842		(5,941)		$ 9,783
Exercise of stock options and issuance of restricted stock (in shares)					(767)
Other	4,934		4,581		$ 353
Other (in shares)					(21)
Stockholders' equity (deficit), ending balance at Aug. 31, 2016	(75,643)	1,183	234,956	894,442	$ (1,206,224)
Ending balance (in shares) at Aug. 31, 2016					71,670
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	63,663			63,663
Cash dividends	(24,088)			(24,088)
Stock-based compensation expense	3,942		3,942
Purchase of treasury stock	(172,913)				$ (172,913)
Purchase of treasury stock (in shares)					6,726
Exercise of stock options and issuance of restricted stock	2,682		(2,203)		$ 4,885
Exercise of stock options and issuance of restricted stock (in shares)					(293)
Other	599		200		$ 399
Other (in shares)					(22)
Stockholders' equity (deficit), ending balance at Aug. 31, 2017	$ (201,758)	1,183	236,895	934,017	$ (1,373,853)
Ending balance (in shares) at Aug. 31, 2017	78,081				78,081
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	$ 71,205			71,205
Cash dividends	(23,971)			(23,971)
Stock-based compensation expense	4,556		4,556
Purchase of treasury stock	(139,178)				$ (139,178)
Purchase of treasury stock (in shares)					5,215
Exercise of stock options and issuance of restricted stock	(118)		(3,140)		$ 3,022
Exercise of stock options and issuance of restricted stock (in shares)					(542)
Other	418		58		$ 360
Other (in shares)					(20)
Stockholders' equity (deficit), ending balance at Aug. 31, 2018	$ (288,846)	$ 1,183	$ 238,369	$ 981,251	$ (1,509,649)
Ending balance (in shares) at Aug. 31, 2018	82,734				82,734