Condensed Consolidated Statements of Stockholders' Equity (USD $) In Thousands	Common Stock [Member]	Additional Paid-in Capital [Member]	Accumulated Other Comprehensive Earnings [Member]	Foreign Currency Translation Adjustments [Member]	Unrealized Derivative Gains (Losses) [Member]	Minimum Retirement Benefit Liability Adjustments [Member]	Deferred Compensation in Equity [Member]	Retained Earnings [Member]	Treasury Stock at Cost [Member]	Treasury Stock Held for Deferred Compensaton [Member]	Total
Balances at Sep. 30, 2010	$ 106	$ 73,915	$ 6,342	$ 23,152	$ (627)	$ (16,183)	$ 4,888	$ 835,919	$ (113,088)	$ (4,888)	$ 803,194
Balance, Treasury Stock, shares at Sep. 30, 2010									(4,223)
Balance, Common Stock, shares at Sep. 30, 2010	72,960
Balance, Treasury stock held for deferred compensation, Shares at Sep. 30, 2010										(356)
Net earnings								22,399			22,399
Cash dividends paid								(4,136)			(4,136)
Purchases of treasury stock									(7,961)		(7,961)
Purchases of treasury stock, shares									(242)
Sales of treasury stock		(1,813)							4,034		2,221
Sales of treasury stock, shares									252
Tax benefit attributable to exercise of stock options		2,230									2,230
Stock-based compensation		2,304									2,304
Purchases of stock by deferred compensation plan		13					46			(46)	13
Purchases of stock by deferred compensation plan, shares									1	(1)
Distribution of stock from deferred compensation plan							(11)			11
Distribution of stock from deferred compensation plan, shares										1
Foreign currency translation adjustments			(2,380)	(2,380)							(2,380)
Reclassification of realized losses on derivatives to earnings			59		59						59
Minimum retirement benefits liability adjustment			(28)			(28)					(28)
Taxes on changes in accumulated other comprehensive earnings			116	138	(22)						116
Balances at Dec. 31, 2010	106	76,649	4,109	20,910	(590)	(16,211)	4,923	854,182	(117,015)	(4,923)	818,031
Balance, Treasury Stock, shares at Dec. 31, 2010									(4,212)
Balance, Common Stock, shares at Dec. 31, 2010	72,960
Balance, Treasury stock held for deferred compensation, Shares at Dec. 31, 2010										(356)
Balances at Sep. 30, 2011	106	81,453	3,626	22,103	(484)	(17,993)	4,581	949,573	(115,661)	(4,581)	919,097
Balance, Treasury Stock, shares at Sep. 30, 2011									(4,070)		(4,070)
Balance, Common Stock, shares at Sep. 30, 2011	72,960										72,960
Balance, Preferred Stock, shares at Sep. 30, 2011											0
Balance, Treasury stock held for deferred compensation, Shares at Sep. 30, 2011										(315)	(315)
Net earnings								28,416			28,416
Cash dividends paid								(4,823)			(4,823)
Purchases of treasury stock									(4,663)		(4,663)
Purchases of treasury stock, shares									(122)
Sales of treasury stock		(683)							2,849		2,166
Sales of treasury stock, shares									186
Tax benefit attributable to exercise of stock options		1,691									1,691
Stock-based compensation		3,647									3,647
Purchases of stock by deferred compensation plan		28					72		18	(72)	46
Purchases of stock by deferred compensation plan, shares									1	(1)
Distribution of stock from deferred compensation plan							(11)			11
Distribution of stock from deferred compensation plan, shares										2
Foreign currency translation adjustments			(8,381)	(8,381)							(8,381)
Reclassification of realized losses on derivatives to earnings			45		45						45
Minimum retirement benefits liability adjustment			31			31					31
Taxes on changes in accumulated other comprehensive earnings			928	945	(17)						928
Balances at Dec. 31, 2011	$ 106	$ 86,136	$ (3,751)	$ 14,667	$ (456)	$ (17,962)	$ 4,642	$ 973,166	$ (117,457)	$ (4,642)	$ 938,200
Balance, Treasury Stock, shares at Dec. 31, 2011									(4,005)		(4,005)
Balance, Common Stock, shares at Dec. 31, 2011	72,960										72,960
Balance, Preferred Stock, shares at Dec. 31, 2011											0
Balance, Treasury stock held for deferred compensation, Shares at Dec. 31, 2011										(314)	(314)