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, 2014	$ 3	$ 397,150	$ 9,505	$ (49,286)	$ 215,613	$ (24,720)	$ 548,265
Balance (in shares) at Aug. 31, 2014	30,951,000					741,000
Purchase of treasury stock						$ (4,677)	(4,677)
Purchase of treasury stock (in shares)						52,000
Issuance of restricted stock (in shares)	33,000
Forfeiture of restricted stock awards (in shares)	(9,000)
Exercise of stock options		49					49
Exercise of stock options (in shares)	3,000
Stock-based compensation		5,969	1,206				7,175
Dividend paid to stockholders					(21,126)		(21,126)
Net income					89,124		89,124
Other comprehensive income (loss)				(52,226)			(52,226)
Balance at Aug. 31, 2015	$ 3	403,168	10,711	(101,512)	283,611	$ (29,397)	566,584
Balance (in shares) at Aug. 31, 2015	30,978,000					793,000
Purchase of treasury stock						$ (3,334)	(3,334)
Purchase of treasury stock (in shares)						43,000
Issuance of restricted stock (in shares)	256,000
Exercise of stock options		80					80
Exercise of stock options (in shares)	4,000
Stock-based compensation		9,121	610				9,731
Dividend paid to stockholders					(21,274)		(21,274)
Net income					88,723		88,723
Other comprehensive income (loss)				(2,439)			(2,439)
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	30,401,307
Purchase of treasury stock						$ (3,193)	$ (3,193)
Purchase of treasury stock (in shares)						39,000
Issuance of restricted stock (in shares)	63,000
Forfeiture of restricted stock awards (in shares)	(37,000)
Exercise of stock options		704					704
Exercise of stock options (in shares)	12,000
Stock-based compensation		9,689	165				9,854
Dividend paid to stockholders					(21,285)		(21,285)
Net income					90,724		90,724
Other comprehensive income (loss)				(6,108)			(6,108)
Balance at Aug. 31, 2017	$ 3	$ 422,762	$ 11,486	$ (110,059)	$ 420,499	$ (35,924)	$ 708,767
Balance (in shares) at Aug. 31, 2017	31,276,000					875,000	30,400,742