Condensed Consolidated Statements of Stockholders' Equity - USD ($) shares in Thousands, $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Balance at Dec. 31, 2014	$ 863,465	$ 489	$ 220,982	$ 649,174	$ (7,180)
Balance (in shares) at Dec. 31, 2014		48,966
Increase (Decrease) in Stockholders' Equity
Net income	53,156			53,156
Translation adjustment, net of tax	(14,864)				(14,864)
Options exercised	7,019	$ 2	7,017
Stock options exercised (in shares)		239
Stock-based compensation	8,744		8,744
Tax benefit of options exercised	(244)		(244)
Shares issued from release of Restricted Stock Units	(3,646)	$ 2	(3,648)
Shares issued from release of Restricted Stock Units (in shares)		205
Repurchase of common stock	(47,144)		(7,615)			$ (39,529)
Repurchase of common stock (in shares)		(1,149)
Cash dividends declared on common stock, $0.46, $0.16, and $0.52 for the period ended September 30, 2015, December 31, 2015 and September 30, 2016, respectively	(22,657)			(22,657)
Common stock issued at $34.32 per share for stock bonus for the periods ended September 30, 2015 and December 31, 2015 and $32.45 September 30, 2016, respectively	552		552
Common stock issued (in shares)		16
Balance at Sep. 30, 2015	844,381	$ 493	225,788	679,673	(22,044)	(39,529)
Balance (in shares) at Sep. 30, 2015		48,277
Increase (Decrease) in Stockholders' Equity
Net income	14,732			14,732
Translation adjustment, net of tax	(6,075)				(6,075)
Pension adjustment, net of tax	(457)				(457)
Options exercised	2,701	$ 1	2,700
Stock options exercised (in shares)		92
Stock-based compensation	2,253		2,253
Tax benefit of options exercised	(74)		(74)
Shares issued from release of Restricted Stock Units	(70)	$ 0	(70)
Shares issued from release of Restricted Stock Units (in shares)		5
Repurchase of common stock	0		7,615			(7,615)
Repurchase of common stock (in shares)		(190)
Retirement of common stock	0	$ (13)		(47,131)		47,144
Cash dividends declared on common stock, $0.46, $0.16, and $0.52 for the period ended September 30, 2015, December 31, 2015 and September 30, 2016, respectively	(7,567)			(7,567)
Balance at Dec. 31, 2015	849,824	$ 481	238,212	639,707	(28,576)
Balance (in shares) at Dec. 31, 2015		48,184
Increase (Decrease) in Stockholders' Equity
Net income	72,341			72,341
Translation adjustment, net of tax	5,244				5,244
Options exercised	6,695	$ 3	6,692
Stock options exercised (in shares)		227
Stock-based compensation	9,039		9,039
Tax benefit of options exercised	140		140
Shares issued from release of Restricted Stock Units	(3,996)	$ 2	(3,998)
Shares issued from release of Restricted Stock Units (in shares)		216
Repurchase of common stock	(53,502)		(6,500)			(47,002)
Repurchase of common stock (in shares)		(1,090)
Cash dividends declared on common stock, $0.46, $0.16, and $0.52 for the period ended September 30, 2015, December 31, 2015 and September 30, 2016, respectively	(24,996)			(24,996)
Common stock issued at $34.32 per share for stock bonus for the periods ended September 30, 2015 and December 31, 2015 and $32.45 September 30, 2016, respectively	315		315
Common stock issued (in shares)		10
Balance at Sep. 30, 2016	$ 861,104	$ 486	$ 243,900	$ 687,052	$ (23,332)	$ (47,002)
Balance (in shares) at Sep. 30, 2016		47,547