CONSOLIDATED STATEMENTS OF EQUITY - USD ($) $ in Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Tax Benefit From Stock Based Compensation [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Total
Balance at Aug. 31, 2016	$ 3	$ 412,369	$ 11,321	$ (103,951)	$ 351,060	$ (32,731)	$ 638,071
Balance (in shares) at Aug. 31, 2016	31,238,000					836,000
Purchase of treasury stock						$ (1,941)	(1,941)
Purchase of treasury stock (in shares)						24,000
Issuance of restricted stock award
Issuance of restricted stock award (in shares)	23,000
Forfeiture of restricted stock awards
Forfeiture of restricted stock awards (in shares)	(2,000)
Exercise of stock options		229					229
Exercise of stock options (in shares)	5,000
Stock-based compensation		5,178	213				5,391
Dividend paid to stockholders					(10,641)		(10,641)
Dividends payable to stockholders					(10,643)		(10,643)
Net income					52,088		52,088
Other comprehensive income (loss)				(860)			(860)
Balance at Feb. 28, 2017	$ 3	417,776	11,534	(104,811)	381,864	$ (34,672)	671,694
Balance (in shares) at Feb. 28, 2017	31,264,000					860,000
Balance at Aug. 31, 2017	$ 3	422,395	11,486	(110,059)	420,866	$ (35,924)	$ 708,767
Balance (in shares) at Aug. 31, 2017	31,276,000					875,000	30,400,742
Purchase of treasury stock						$ (1,833)	$ (1,833)
Purchase of treasury stock (in shares)						21,000
Issuance of restricted stock award
Issuance of restricted stock award (in shares)	38,000
Forfeiture of restricted stock awards
Forfeiture of restricted stock awards (in shares)	(7,000)
Exercise of stock options		269					269
Exercise of stock options (in shares)	4,000
Stock-based compensation		4,881					4,881
Dividend paid to stockholders					(10,645)		(10,645)
Dividends payable to stockholders					(10,652)		(10,652)
Net income					36,638		36,638
Other comprehensive income (loss)				3,809			3,809
Balance at Feb. 28, 2018	$ 3	$ 427,545	$ 11,486	$ (106,250)	$ 436,207	$ (37,757)	$ 731,234
Balance (in shares) at Feb. 28, 2018	31,311,000					896,000	30,414,382