Consolidated Statements of Changes in Stockholders' Equity (USD $) In Thousands, except Share data, unless otherwise specified	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Retained Earnings [Member]	Accumulated Other Non-Owner Changes to Equity [Member]
Balance at Dec. 31, 2009	$ 684,713	$ 560	$ 270,784	$ (15,839)	$ 478,704	$ (49,496)
Balance (in shares) at Dec. 31, 2009		55,974,000		1,182,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	66,180				53,278	12,902
Dividends paid	(17,461)				(17,461)
Common stock repurchases	(28,100)			(28,100)
Common stock repurchases (in shares)				1,483,527
Employee stock plans		5
Employee stock plans, other			7,503
Employee stock plans (in shares)		544,366
Employee stock plans, shares withheld for taxes (in shares)				25,000
Employee stock plans, shares withheld for taxes				(440)
Dividends paid to holders of certain restricted stock units					(281)
Employee stock plans, total	6,787
Balance at Dec. 31, 2010	712,119	565	278,287	(44,379)	514,240	(36,594)
Balance (in shares) at Dec. 31, 2010		56,518,000		2,691,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	26,255				64,715	(38,460)
Dividends paid	(18,629)				(18,629)
Common stock repurchases	(34,066)			(34,066)
Common stock repurchases (in shares)				1,509,156
Employee stock plans		21
Employee stock plans, other			43,202
Employee stock plans (in shares)		2,075,385
Employee stock plans, shares withheld for taxes (in shares)				54,000
Employee stock plans, shares withheld for taxes				(1,124)
Dividends paid to holders of certain restricted stock units					(140)
Convertible debt redemption, net of tax	(5,238)		(5,238)
Employee stock plans, total	41,959
Balance at Dec. 31, 2011	722,400	586	316,251	(79,569)	560,186	(75,054)
Balance (in shares) at Dec. 31, 2011		58,594,000		4,254,000
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	103,551				95,249	8,302
Dividends paid	(21,662)				(21,662)
Common stock repurchases	(19,037)			(19,037)
Common stock repurchases (in shares)				700,000
Employee stock plans		6
Employee stock plans, other			16,337
Employee stock plans (in shares)		608,227
Employee stock plans, shares withheld for taxes (in shares)				46,000
Employee stock plans, shares withheld for taxes				(1,150)
Dividends paid to holders of certain restricted stock units					(327)
Employee stock plans, total	14,866
Balance at Dec. 31, 2012	$ 800,118	$ 592	$ 332,588	$ (99,756)	$ 633,446	$ (66,752)
Balance (in shares) at Dec. 31, 2012		59,202,000		5,000,000