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	Comprehensive Income
Balance at Dec. 31, 2008	$ 749,026	$ 490	$ 136,867	$ 605,950	$ 5,719
Balance (in shares) at Dec. 31, 2008		48,971
Comprehensive income:
Net income	12,217			12,217			12,217
Other comprehensive income:
Translation adjustment	13,043				13,043		13,043
Comprehensive income	25,260						25,260
Options exercised	7,627	3	7,624
Options exercised (in shares)		396
Stock compensation expense	1,690		1,690
Tax benefit of options exercised	(445)		(445)
Cash dividends declared on common stock, $0.50 per share, for the year ended December 31, 2011 and $0.40 per share, December 31, 2010, and December 31, 2009	(19,674)			(19,674)
Common stock issued at $30.91, $26.42, and $27.76 per share for the year ended December 31, 2011, December 31, 2010, and December 31, 2009, respectively	300		300
Common stock issued (in shares)		10
Balance at Dec. 31, 2009	763,784	493	146,036	598,493	18,762
Balance (in shares) at Dec. 31, 2009		49,377
Comprehensive income:
Net income	28,586			28,586			28,586
Other comprehensive income:
Translation adjustment	(4,135)				(4,135)		(4,135)
Comprehensive income	24,451						24,451
Options exercised	17,948	7	17,941
Options exercised (in shares)		707
Stock compensation expense	3,577		3,577
Tax benefit of options exercised	(2,430)		(2,430)
Cash dividends declared on common stock, $0.50 per share, for the year ended December 31, 2011 and $0.40 per share, December 31, 2010, and December 31, 2009	(19,838)			(19,838)
Common stock issued at $30.91, $26.42, and $27.76 per share for the year ended December 31, 2011, December 31, 2010, and December 31, 2009, respectively	301		301
Common stock issued (in shares)		12
Balance at Dec. 31, 2010	787,793	500	165,425	607,241	14,627
Balance (in shares) at Dec. 31, 2010		50,096
Comprehensive income:
Net income	50,900			50,900			50,900
Other comprehensive income:
Translation adjustment	(7,844)				(7,844)		(7,844)
Comprehensive income	43,056						43,056
Options exercised	214		214
Options exercised (in shares)	8	8
Stock compensation expense	6,194		6,194
Tax benefit of options exercised	(1,554)		(1,554)
Repurchase of common stock	(53,208)					(53,208)
Repurchase of common stock (in shares)		(1,948)
Retirement of common stock		(19)		(53,189)		53,208
Cash dividends declared on common stock, $0.50 per share, for the year ended December 31, 2011 and $0.40 per share, December 31, 2010, and December 31, 2009	(24,336)			(24,336)
Common stock issued at $30.91, $26.42, and $27.76 per share for the year ended December 31, 2011, December 31, 2010, and December 31, 2009, respectively	204		204
Common stock issued (in shares)		7
Balance at Dec. 31, 2011	$ 758,363	$ 481	$ 170,483	$ 580,616	$ 6,783
Balance (in shares) at Dec. 31, 2011		48,163