Consolidated Statements Of Shareholders' Equity (USD $) In Thousands, except Share data	Common Shares Issued [Member]	Additional Paid-In Capital [Member]	Retained Earnings [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Sub-Total [Member]	Treasury Stock [Member]	Total
Beginning Balance at Dec. 31, 2008	$ 570	$ 153,766	$ 134,006	$ (6,450)	$ 281,892	$ (28,615)	$ 253,277
Beginning Balance, shares at Dec. 31, 2008	56,961,297					2,902,264
Net income			39,159		39,159		39,159
Translation adjustments, net of tax of $(0.3), $0.4 and $(0.1) million for year 2009, 2010 and 2011 respectively				3,526	3,526		3,526
Unrecognized loss on derivatives, net of tax of $(0.8), $0.1 and $0.4 million for year 2009, 2010 and 2011 respectively				(1,265)	(1,265)		(1,265)
Employee benefit plans, net of tax of $2.1, $(0.3) and $(5.7) million for year 2009, 2010 and 2011 respectively				3,183	3,183		3,183
Employee and director stock plans	4	4,579			4,583		4,583
Employee and director stock plans, shares	415,850
Conversion of Notes	12	5,891			5,903		5,903
Conversion of Notes, shares	1,176,470
Treasury stock purchased						(1,280)	(1,280)
Treasury stock purchased, shares						103,773
Ending Balance at Dec. 31, 2009	586	164,236	173,165	(1,006)	336,981	(29,895)	307,086
Ending Balance, shares at Dec. 31, 2009	58,553,617					3,006,037
Net income			34,850		34,850		34,850
Translation adjustments, net of tax of $(0.3), $0.4 and $(0.1) million for year 2009, 2010 and 2011 respectively				(3,594)	(3,594)		(3,594)
Unrecognized loss on derivatives, net of tax of $(0.8), $0.1 and $0.4 million for year 2009, 2010 and 2011 respectively				573	573		573
Employee benefit plans, net of tax of $2.1, $(0.3) and $(5.7) million for year 2009, 2010 and 2011 respectively				(47)	(47)		(47)
Employee and director stock plans	4	5,048			5,052		5,052
Employee and director stock plans, shares	435,961
Treasury stock purchased						(956)	(956)
Treasury stock purchased, shares						64,683
Ending Balance at Dec. 31, 2010	590	169,284	208,015	(4,074)	373,815	(30,851)	342,964
Ending Balance, shares at Dec. 31, 2010	58,989,578					3,070,720
Net income			39,224		39,224		39,224
Translation adjustments, net of tax of $(0.3), $0.4 and $(0.1) million for year 2009, 2010 and 2011 respectively				(1,123)	(1,123)		(1,123)
Unrecognized loss on derivatives, net of tax of $(0.8), $0.1 and $0.4 million for year 2009, 2010 and 2011 respectively				756	756		756
Employee benefit plans, net of tax of $2.1, $(0.3) and $(5.7) million for year 2009, 2010 and 2011 respectively				(9,076)	(9,076)		(9,076)
Employee and director stock plans	4	4,790			4,794		4,794
Employee and director stock plans, shares	392,058
Treasury stock purchased						(422)	(422)
Treasury stock purchased, shares						29,699
Ending Balance at Dec. 31, 2011	$ 594	$ 174,074	$ 247,239	$ (13,517)	$ 408,390	$ (31,273)	$ 377,117
Ending Balance, shares at Dec. 31, 2011	59,381,636					3,100,419