CONSOLIDATED STATEMENTS OF SHAREHOLDERS EQUITY AND COMPREHENSIVE INCOME (USD $) In Thousands, except Share data, unless otherwise specified	Common Stock [Member]	Capital In Excess of Par [Member]	Retained Earnings [Member]	Treasury Stock [Member]	Comprehensive Income [Member]	Accumulated Other Comprehensive Income (Loss) [Member]	Total
Balance at Dec. 31, 2008	$ 31,584	$ 48,140	$ 414,748	$ (35,835)		$ (44,700)	$ 413,937
Balance (in shares) at Dec. 31, 2008	29,721,590
Comprehensive income:
Net earnings			22,026		22,026		22,026
Other comprehensive income, net of tax:
Foreign currency translation adjustments					3,525	3,525	3,525
Defined benefit pension plans					3,993	3,993	3,993
Defined benefit post-retirement plans					(744)	(744)	(744)
Total comprehensive income					28,800
Cash dividends			(14,866)				(14,866)
Treasury stock purchases	0			11			11
Tax settlement on stock-based compensation		3,880					3,880
Stock -based compensation		2,943					2,943
Exercise of stock options	34	654		285			973
Exercise of stock options (in shares)	49,250
Balance at Dec. 31, 2009	31,618	55,617	421,908	(35,539)		(37,926)	435,678
Balance (in shares) at Dec. 31, 2009	29,770,840
Comprehensive income:
Net earnings			43,823		43,823		43,823
Other comprehensive income, net of tax:
Foreign currency translation adjustments					(960)	(960)	(960)
Defined benefit pension plans					1,556	1,556	1,556
Defined benefit post-retirement plans					684	684	684
Total comprehensive income					45,103
Cash dividends			(15,017)				(15,017)
Stock -based compensation		4,627					4,627
Exercise of stock options	515	14,567		487			15,569
Exercise of stock options (in shares)	533,641
Balance at Dec. 31, 2010	32,133	74,811	450,714	(35,052)		(36,646)	485,960
Balance (in shares) at Dec. 31, 2010	30,304,481
Comprehensive income:
Net earnings			65,971		65,971		65,971
Other comprehensive income, net of tax:
Foreign currency translation adjustments					(3,316)	(3,316)	(3,316)
Defined benefit pension plans					(38,441)	(38,441)	(38,441)
Defined benefit post-retirement plans					(533)	(533)	(533)
Total comprehensive income					23,681
Cash dividends			(15,230)				(15,230)
Treasury stock purchases		5,310					5,310
Exercise of stock options	185	7,477		150			7,812
Exercise of stock options (in shares)	188,649
Balance at Dec. 31, 2011	$ 32,318	$ 87,598	$ 501,455	$ (34,902)		$ (78,936)	$ 507,533
Balance (in shares) at Dec. 31, 2011							30,493,130