Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Total	Preferred Stock [Member]	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Noncontrolling Interest [Member]	Net Change in Net Actuarial Losses [Member] Accumulated Other Comprehensive Income (Loss) [Member]	Net Change in Prior Service Costs (Credit) [Member] Accumulated Other Comprehensive Income (Loss) [Member]
Balance at Aug. 31, 2009	$ 370,971	$ 2	$ 42,295	$ 115,358	$ 38,714	$ 492,513	$ (322,812)	$ 4,901
Net income	44,111					43,890		221
Foreign currency translation gain (loss)					(27,898)
Net change in net actuarial losses	(17,094)								(17,042)	(52)
Total comprehensive income (loss)	(881)
Cash dividends paid	(16,754)					(16,754)
Acquisition of ICO	132,651		5,100	127,551
Cash distributions to noncontrolling interests	0
Issuance of treasury stock	35						35
Stock options exercised	4,010		214	3,796
Restricted stock issued, net of forfeitures	0		123	(123)
Redemption of common stock to cover tax withholdings	(956)		(42)	(914)
Preferred stock redemption	(2)	(2)
Amortization of restricted stock	4,066			4,066
Balance at Aug. 31, 2010	493,140	0	47,690	249,734	(6,278)	519,649	(322,777)	5,122
Net income	41,685					40,996		689
Foreign currency translation gain (loss)					42,550
Net change in net actuarial losses	13,735								11,703	2,032
Total comprehensive income (loss)	97,970
Cash dividends paid	(19,389)					(19,389)
Cash distributions to noncontrolling interests	(700)							(700)
Capital contributions from noncontrolling interests	690							690
Purchase of treasury stock	(22,154)						(22,154)
Issuance of treasury stock	199			27			172
Stock options exercised	969		52	917
Restricted stock issued, net of forfeitures	0		121	(121)
Redemption of common stock to cover tax withholdings	(1,043)		(47)	(996)
Preferred stock redemption	0
Amortization of restricted stock	4,623			4,623
Balance at Aug. 31, 2011	554,305	0	47,816	254,184	50,007	541,256	(344,759)	5,801
Net income	52,049					50,887		1,162
Foreign currency translation gain (loss)					(46,557)			(90)
Net change in net actuarial losses	(9,371)								(6,200)	(3,171)
Total comprehensive income (loss)	(3,969)
Cash dividends paid	(20,938)					(20,938)
Cash distributions to noncontrolling interests	(580)							(580)
Purchase of treasury stock	(26,752)						(26,752)
Issuance of treasury stock	432			20			412
Stock options exercised	915		51	864
Restricted stock issued, net of forfeitures	0		108	(108)
Redemption of common stock to cover tax withholdings	(382)		(17)	(365)
Preferred stock redemption	0
Amortization of restricted stock	4,658			4,658
Balance at Aug. 31, 2012	$ 507,689	$ 0	$ 47,958	$ 259,253	$ (5,921)	$ 571,205	$ (371,099)	$ 6,293