Consolidated Statements of Stockholders' Equity (USD $) In Thousands, unless otherwise specified	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income	Treasury Stock
Balance at Dec. 31, 2011	$ 758,363	$ 481	$ 170,483	$ 580,616	$ 6,783
Balance (in shares) at Dec. 31, 2011		48,163
Increase (Decrease) in Stockholders' Equity
Net income	41,918			41,918
Translation adjustment, net of tax	5,559				5,559
Pension adjustment net of tax	(243)				(243)
Options exercised	4,925	2	4,923
Options exercised (in shares)		185
Stock-based compensation expense	10,195		10,195
Tax benefit of options exercised	(233)		(233)
Cash dividends declared on common stock, $0.545, $0.375 and $0.625 per share for the year ended December 31, 2014, 2013 and 2012, respectively	(30,225)			(30,225)
Shares issued from release of restricted stock units	(1,109)		(1,109)
Shares issued from release of restricted stock units (in shares)		62
Common stock issued at $35.87, $33.81 and $33.71 per share for the year ended December 31, 2014, 2013 and 2012, respectively	418		418
Common stock issued (in shares)		12
Balance at Dec. 31, 2012	789,568	483	184,677	592,309	12,099
Balance (in shares) at Dec. 31, 2012		48,422
Increase (Decrease) in Stockholders' Equity
Net income	50,971			50,971
Translation adjustment, net of tax	5,941				5,941
Pension adjustment net of tax	46				46
Options exercised	15,057	5	15,052
Options exercised (in shares)		512
Stock-based compensation expense	12,090		12,090
Tax benefit of options exercised	(2,645)		(2,645)
Repurchase of common stock	(9,825)					(9,825)
Repurchase of common stock (in shares)		(342)
Retirement of common stock		(4)		(9,821)		9,825
Cash dividends declared on common stock, $0.545, $0.375 and $0.625 per share for the year ended December 31, 2014, 2013 and 2012, respectively	(18,170)			(18,170)
Shares issued from release of restricted stock units	(2,072)	2	(2,074)
Shares issued from release of restricted stock units (in shares)		111
Common stock issued at $35.87, $33.81 and $33.71 per share for the year ended December 31, 2014, 2013 and 2012, respectively	318		318
Common stock issued (in shares)		9
Balance at Dec. 31, 2013	841,279	486	207,418	615,289	18,086
Balance (in shares) at Dec. 31, 2013	48,712	48,712
Increase (Decrease) in Stockholders' Equity
Net income	63,531			63,531
Translation adjustment, net of tax	(24,896)				(24,896)
Pension adjustment net of tax	(370)				(370)
Options exercised	4,582	2	4,580
Options exercised (in shares)		161
Stock-based compensation expense	12,354		12,354
Tax benefit of options exercised	(268)		(268)
Repurchase of common stock	(2,981)					(2,981)
Repurchase of common stock (in shares)		(95)
Retirement of common stock		(1)		(2,980)		2,981
Cash dividends declared on common stock, $0.545, $0.375 and $0.625 per share for the year ended December 31, 2014, 2013 and 2012, respectively	(26,666)			(26,666)
Shares issued from release of restricted stock units	(3,502)	2	(3,504)
Shares issued from release of restricted stock units (in shares)		177
Common stock issued at $35.87, $33.81 and $33.71 per share for the year ended December 31, 2014, 2013 and 2012, respectively	402		402
Common stock issued (in shares)		11
Balance at Dec. 31, 2014	$ 863,465	$ 489	$ 220,982	$ 649,174	$ (7,180)
Balance (in shares) at Dec. 31, 2014	48,966	48,966