Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance (in shares) at Dec. 31, 2019		44,209,000
Beginning Balance at Dec. 31, 2019	$ 891,957	$ 442	$ 280,216	$ 645,507	$ (24,829)	$ (9,379)
Increase (Decrease) in Stockholders' Equity
Net income	157,362			157,362
Translation adjustment, net of tax	3,170				3,170
Pension adjustment and other, net of tax	88				88
Stock-based compensation	8,481		8,481
Shares issued from release of Restricted Stock Units (in shares)		165,000
Shares issued from release of Restricted Stock Units	(7,903)	$ 2	(7,905)
Repurchase of common stock (in shares)		(902,000)
Repurchase of common stock	(62,679)					(62,679)
Dividends, Common Stock, Cash	(30,018)			(30,018)
Common stock issued (in shares)		4,000
Common stock issued	342		342
Ending Balance (in shares) at Sep. 30, 2020		43,476,000
Ending Balance at Sep. 30, 2020	960,800	$ 444	281,134	772,851	(21,571)	(72,058)
Beginning Balance (in shares) at Jun. 30, 2020		43,473,000
Beginning Balance at Jun. 30, 2020	894,212	$ 444	277,625	716,038	(27,837)	(72,058)
Increase (Decrease) in Stockholders' Equity
Net income	67,057			67,057
Translation adjustment, net of tax	6,238				6,238
Pension adjustment and other, net of tax	28				28
Stock-based compensation	3,651		3,651
Shares issued from release of Restricted Stock Units (in shares)		3,000
Shares issued from release of Restricted Stock Units	(162)	$ 0	(162)
Dividends, Common Stock, Cash	(10,244)			(10,244)
Common stock issued (in shares)		0
Common stock issued	20		20
Ending Balance (in shares) at Sep. 30, 2020		43,476,000
Ending Balance at Sep. 30, 2020	960,800	$ 444	281,134	772,851	(21,571)	(72,058)
Beginning Balance (in shares) at Dec. 31, 2020		43,326,000
Beginning Balance at Dec. 31, 2020	980,943	$ 433	284,007	720,441	(10,428)	(13,510)
Increase (Decrease) in Stockholders' Equity
Net income	196,650			196,650
Translation adjustment, net of tax	(6,649)				(6,649)
Pension adjustment and other, net of tax	75				75
Stock-based compensation	12,432		12,432
Shares issued from release of Restricted Stock Units (in shares)		106,000
Shares issued from release of Restricted Stock Units	(5,396)	$ 1	(5,397)
Repurchase of common stock (in shares)		(222,000)
Repurchase of common stock	(24,125)					(24,125)
Dividends, Common Stock, Cash	(31,619)			(31,619)
Common stock issued (in shares)		7,000
Common stock issued	692	$ 1	691
Ending Balance (in shares) at Sep. 30, 2021		43,217,000
Ending Balance at Sep. 30, 2021	1,123,003	$ 435	291,733	885,472	(17,002)	(37,635)
Beginning Balance (in shares) at Jun. 30, 2021		43,437,000
Beginning Balance at Jun. 30, 2021	1,086,905	$ 435	289,261	822,497	(11,778)	(13,510)
Increase (Decrease) in Stockholders' Equity
Net income	73,778			73,778
Translation adjustment, net of tax	(4,889)				(4,889)
Pension adjustment and other, net of tax	(335)				(335)
Stock-based compensation	2,606		2,606
Shares issued from release of Restricted Stock Units (in shares)		2,000
Shares issued from release of Restricted Stock Units	(134)	$ 0	(134)
Repurchase of common stock (in shares)		(222,000)
Repurchase of common stock						(24,125)
Dividends, Common Stock, Cash	(10,803)			(10,803)
Ending Balance (in shares) at Sep. 30, 2021		43,217,000
Ending Balance at Sep. 30, 2021	$ 1,123,003	$ 435	$ 291,733	$ 885,472	$ (17,002)	$ (37,635)