Statement Of Stockholders Equity (USD $) In Thousands	Common Stock [Member]	Capital In Excess of Stated Valuel [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income [Member]	Total
Beginning Balance at Aug. 31, 2009	$ 18,129	$ 28,944	$ (91,998)	$ 249,588	$ 2,995	$ 207,658
Shares, Outstanding, Beginning Balance at Aug. 31, 2009	18,129		5,763
Net earnings				24,862		24,862
Other comprehensive income					(1,640)	(1,640)
Total comprehensive income						23,222
Cash dividends per share				(4,051)		(4,051)
Issuance of common stock under share compensation plan, value	56	(417)	1,037	(127)		549
Issuance of common stock under share compensation plan, shares	56		(65)
Excess tax benefits from share-based compensation		127				127
Share-based compensation expense		2,102				2,102
Ending Balance at Aug. 31, 2010	18,185	30,756	(90,961)	270,272	1,355	229,607
Shares, Outstanding, Ending Balance at Aug. 31, 2010	18,185		5,698
Net earnings				36,802		36,802
Other comprehensive income					5,107	5,107
Total comprehensive income						41,909
Cash dividends per share				(4,342)		(4,342)
Issuance of common stock under share compensation plan, value	189	2,547				2,736
Issuance of common stock under share compensation plan, shares	189
Excess tax benefits from share-based compensation		2,487				2,487
Share-based compensation expense		3,268				3,268
Ending Balance at Aug. 31, 2011	18,374	39,058	(90,961)	302,732	6,462	275,665
Shares, Outstanding, Ending Balance at Aug. 31, 2011	18,374		5,698
Net earnings				43,277		43,277
Other comprehensive income					(7,339)	(7,339)
Total comprehensive income						35,938
Cash dividends per share				(4,894)		(4,894)
Issuance of common stock under share compensation plan, value	47	(57)				(10)
Issuance of common stock under share compensation plan, shares	47
Excess tax benefits from share-based compensation		374				374
Share-based compensation expense		3,765				3,765
Ending Balance at Aug. 31, 2012	$ 18,421	$ 43,140	$ (90,961)	$ 341,115	$ (877)	$ 310,838
Shares, Outstanding, Ending Balance at Aug. 31, 2012	18,421		5,698