Condensed Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common stock	Additional paid-in	Treasury stock	Retained earnings	Accumulated other comprehensive loss
Beginning balance (in shares) at Dec. 31, 2018		48,082,800		(600,000)
Beginning balance at Dec. 31, 2018	$ 1,035,744	$ 481	$ 354,210	$ (42,543)	$ 769,575	$ (45,979)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	95,783				95,783
Other comprehensive income, net of tax expense	(8,294)					(8,294)
Dividends	(43,966)				(43,966)
Exercise of stock options (in shares)		156,038
Exercise of stock options	5,274	$ 2	5,272
Issuance of shares under employee stock purchase plan (in shares)		32,154
Issuance of shares under employee stock purchase plan	1,995		1,995
Vested restricted stock (in shares)		167,746
Vested restricted stock	0	$ 1	(1)
Repurchase and retirement of common stock (in shares)		(852,803)		600,000
Repurchase and retirement of common stock	(20,562)	$ (8)	(9,832)	$ 42,543	(53,265)
Share based compensation	18,394		18,329		65
Ending balance (in shares) at Sep. 30, 2019		47,585,935		0
Ending balance at Sep. 30, 2019	1,084,368	$ 476	369,973	$ 0	768,192	(54,273)
Beginning balance (in shares) at Jun. 30, 2019		47,765,869		0
Beginning balance at Jun. 30, 2019	1,072,098	$ 478	365,687	$ 0	752,040	(46,107)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	30,745				30,745
Other comprehensive income, net of tax expense	(8,166)					(8,166)
Vested restricted stock (in shares)		26,989
Vested restricted stock	0
Repurchase and retirement of common stock (in shares)		(206,923)
Repurchase and retirement of common stock	(16,755)	$ (2)	(2,160)		(14,593)
Share based compensation	6,446		6,446
Ending balance (in shares) at Sep. 30, 2019		47,585,935		0
Ending balance at Sep. 30, 2019	1,084,368	$ 476	369,973	$ 0	768,192	(54,273)
Beginning balance (in shares) at Dec. 31, 2019		47,654,929		0
Beginning balance at Dec. 31, 2019	1,311,192	$ 476	465,652	$ 0	891,526	(46,462)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	92,580				92,580
Other comprehensive income, net of tax expense	$ (11,532)					(11,532)
Exercise of stock options (in shares)	41,530	41,530
Exercise of stock options	$ 952		1,583		(631)
Issuance of shares under employee stock purchase plan (in shares)		53,694
Issuance of shares under employee stock purchase plan	3,303		3,303
Exercise of 3.25% Convertible Note	(12)		(12)
Vested restricted stock (in shares)		267,894
Vested restricted stock	0	$ 3	(3)
Repurchase and retirement of common stock (in shares)		(3,250,706)
Repurchase and retirement of common stock	(238,905)	$ (31)	(37,541)		(201,333)
Share based compensation	18,643		18,643
Other, net	116		116
Ending balance (in shares) at Sep. 30, 2020		44,767,341		0
Ending balance at Sep. 30, 2020	1,176,337	$ 448	451,741	$ 0	782,142	(57,994)
Beginning balance (in shares) at Jun. 30, 2020		46,892,691		0
Beginning balance at Jun. 30, 2020	1,263,168	$ 469	467,267	$ 0	850,232	(54,800)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income	60,883				60,883
Other comprehensive income, net of tax expense	(3,194)					(3,194)
Vested restricted stock (in shares)		19,893
Vested restricted stock	0
Repurchase and retirement of common stock (in shares)		(2,145,243)
Repurchase and retirement of common stock	(150,436)	$ (21)	(21,442)		(128,973)
Share based compensation	5,800		5,800
Other, net	116		116
Ending balance (in shares) at Sep. 30, 2020		44,767,341		0
Ending balance at Sep. 30, 2020	$ 1,176,337	$ 448	$ 451,741	$ 0	$ 782,142	$ (57,994)