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, 2018	$ 855,514	$ 453	$ 276,504	$ 628,207	$ (24,650)	$ (25,000)
Balance (in shares) at Dec. 31, 2018		44,998
Increase (Decrease) in Stockholders' Equity
Net income	62,239			62,239
Translation adjustment, net of tax	28				28
Pension adjustment, net of tax	100				100
Stock-based compensation	6,127		6,127
Shares issued from release of Restricted Stock Units	(5,897)	$ 2	(5,899)
Shares issued from release of Restricted Stock Units (in shares)		177
Repurchase of common stock	(30,000)		0			(30,000)
Repurchase of common stock (in shares)		(505)
Retirement of common stock	0	$ (9)		(54,991)		55,000
Cash dividends declared on common stock	(19,926)			(19,926)
Common stock issued	292		292
Common stock issued (in shares)		5
Balance at Jun. 30, 2019	868,421	$ 446	277,024	615,529	(24,578)	0
Balance (in shares) at Jun. 30, 2019		44,675
Balance at Mar. 31, 2019	835,418	$ 455	274,836	641,168	(26,041)	(55,000)
Balance (in shares) at Mar. 31, 2019		44,662
Increase (Decrease) in Stockholders' Equity
Net income	39,577			39,577
Translation adjustment, net of tax	1,363				1,363
Pension adjustment, net of tax	100				100
Stock-based compensation	2,224		2,224
Shares issued from release of Restricted Stock Units	(36)		(36)
Shares issued from release of Restricted Stock Units (in shares)		13
Retirement of common stock		$ 9		(54,991)		(55,000)
Cash dividends declared on common stock	0			10,225
Common stock issued	(10,225)
Balance at Jun. 30, 2019	868,421	$ 446	277,024	615,529	(24,578)	0
Balance (in shares) at Jun. 30, 2019		44,675
Balance at Dec. 31, 2019	891,957	$ 442	280,216	645,507	(24,829)	(9,379)
Balance (in shares) at Dec. 31, 2019		44,209
Increase (Decrease) in Stockholders' Equity
Net income	90,305			90,305
Translation adjustment, net of tax	(3,069)				(3,069)
Pension adjustment, net of tax	61				61
Stock-based compensation	4,830		4,830
Shares issued from release of Restricted Stock Units	(7,741)	$ 2	(7,743)
Shares issued from release of Restricted Stock Units (in shares)		162
Repurchase of common stock	(62,679)		0			(62,679)
Repurchase of common stock (in shares)		(902)
Cash dividends declared on common stock	(19,774)			(19,774)
Common stock issued	322		322
Common stock issued (in shares)		4
Balance at Jun. 30, 2020	894,212	$ 444	277,625	716,038	(27,837)	(72,058)
Balance (in shares) at Jun. 30, 2020		43,473
Balance at Mar. 31, 2020	841,594	$ 444	272,872	672,485	(32,149)	(72,058)
Balance (in shares) at Mar. 31, 2020		43,464
Increase (Decrease) in Stockholders' Equity
Net income	53,479			53,479
Translation adjustment, net of tax	4,525				4,525
Pension adjustment, net of tax	(213)				(213)
Stock-based compensation	4,797		4,797
Shares issued from release of Restricted Stock Units	(44)		(44)
Shares issued from release of Restricted Stock Units (in shares)		9
Cash dividends declared on common stock	(9,926)			(9,926)
Balance at Jun. 30, 2020	$ 894,212	$ 444	$ 277,625	$ 716,038	$ (27,837)	$ (72,058)
Balance (in shares) at Jun. 30, 2020		43,473