Consolidated Statements of Changes in Stockholders' Equity (Unaudited) - USD ($) $ in Thousands	Total	Cumulative Effect, Period of Adoption, Adjustment	Common Stock	Additional Paid-in Capital	Retained Deficit	Retained Deficit Cumulative Effect, Period of Adoption, Adjustment	Accumulated Other Comprehensive Income (Loss)
Accounting Standards Update [Extensible List]	us-gaap:AccountingStandardsUpdate201602Member
Balance (in shares) at Dec. 31, 2018			39,506,000
Balance at Dec. 31, 2018	$ 223,590	$ (709)	$ 40	$ 453,193	$ (218,646)	$ (709)	$ (10,997)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	32,637		0	0	32,637		0
Foreign currency translation	214		0	0	0		214
Interest rate swaps, net of the change in taxes	(269)		$ 0	0	0		(269)
Repurchases of common stock, net of retirements (shares)			(155,000)
Repurchases of common stock, net of retirements	(23,097)		$ (1)	0	(23,096)		0
Share-based compensation	3,259		$ 0	3,259	0		0
Issuance of shares under share-based compensation plans (shares)			328,000
Issuance of stock under share-based compensation plans	7,071		$ 1	7,070	0		0
Declaration of cash dividends	(17,819)		$ 0	0	(17,819)		0
Balance (in shares) at Mar. 31, 2019			39,679,000
Balance at Mar. 31, 2019	224,877		$ 40	463,522	(227,633)		(11,052)
Balance (in shares) at Dec. 31, 2018			39,506,000
Balance at Dec. 31, 2018	223,590	$ (709)	$ 40	453,193	(218,646)	$ (709)	(10,997)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	164,027
Foreign currency translation	1,422
Interest rate swaps, net of the change in taxes	$ (1,509)
Balance (in shares) at Jun. 30, 2019	39,897,898		39,898,000
Balance at Jun. 30, 2019	$ 343,169		$ 40	472,390	(118,177)		(11,084)
Balance (in shares) at Mar. 31, 2019			39,679,000
Balance at Mar. 31, 2019	224,877		$ 40	463,522	(227,633)		(11,052)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	131,390		0	0	131,390		0
Foreign currency translation	1,208		0	0	0		1,208
Interest rate swaps, net of the change in taxes	(1,240)		0	0	0		(1,240)
Share-based compensation	3,335		$ 0	3,335	0		0
Issuance of shares under share-based compensation plans (shares)			219,000
Issuance of stock under share-based compensation plans	5,533		$ 0	5,533	0		0
Declaration of cash dividends	$ (21,934)		$ 0	0	(21,934)		0
Balance (in shares) at Jun. 30, 2019	39,897,898		39,898,000
Balance at Jun. 30, 2019	$ 343,169		$ 40	472,390	(118,177)		(11,084)
Balance (in shares) at Dec. 31, 2019	40,074,160		40,074,000
Balance at Dec. 31, 2019	$ 410,180		$ 40	485,239	(64,740)		(10,359)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	30,912		0	0	30,912		0
Foreign currency translation	(5,430)		0	0	0		(5,430)
Interest rate swaps, net of the change in taxes	(8,510)		$ 0	0	0		(8,510)
Repurchases of common stock, net of retirements (shares)			(362,000)
Repurchases of common stock, net of retirements	(66,619)		$ 0	0	(66,619)		0
Share-based compensation	3,654		$ 0	3,654	0		0
Issuance of shares under share-based compensation plans (shares)			219,000
Issuance of stock under share-based compensation plans	6,358		$ 0	6,358	0		0
Declaration of cash dividends	(22,147)		$ 0	0	(22,147)		0
Balance (in shares) at Mar. 31, 2020			39,931,000
Balance at Mar. 31, 2020	$ 348,398		$ 40	495,251	(122,594)		(24,299)
Balance (in shares) at Dec. 31, 2019	40,074,160		40,074,000
Balance at Dec. 31, 2019	$ 410,180		$ 40	485,239	(64,740)		(10,359)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	188,467
Foreign currency translation	(3,296)
Interest rate swaps, net of the change in taxes	$ (11,077)
Balance (in shares) at Jun. 30, 2020	40,041,683		40,042,000
Balance at Jun. 30, 2020	$ 486,791		$ 40	503,271	8,212		(24,732)
Balance (in shares) at Mar. 31, 2020			39,931,000
Balance at Mar. 31, 2020	348,398		$ 40	495,251	(122,594)		(24,299)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income	157,555		0	0	157,555		0
Foreign currency translation	2,134		0	0	0		2,134
Interest rate swaps, net of the change in taxes	(2,567)		$ 0	0	0		(2,567)
Repurchases of common stock, net of retirements (shares)			(19,000)
Repurchases of common stock, net of retirements	(3,584)		$ 0	0	(3,584)		0
Share-based compensation	3,567		$ 0	3,567	0		0
Issuance of shares under share-based compensation plans (shares)			130,000
Issuance of stock under share-based compensation plans	4,453		$ 0	4,453	0		0
Declaration of cash dividends	$ (23,165)		$ 0	0	(23,165)		0
Balance (in shares) at Jun. 30, 2020	40,041,683		40,042,000
Balance at Jun. 30, 2020	$ 486,791		$ 40	$ 503,271	$ 8,212		$ (24,732)