Consolidated Statements of Changes in Stockholders' Equity (Unaudited) Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Deficit	Accumulated Other Comprehensive Income (Loss)
Balance (in shares) at Dec. 31, 2017		40,212,000
Balance at Dec. 31, 2017	$ 223,146	$ 40	$ 426,750	$ (196,316)	$ (7,328)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	31,339	0	0	31,339	0
Foreign currency translation	976	0	0	0	976
Interest rate swaps, net of the change in taxes	824	$ 0	0	0	824
Repurchases of common stock, net of retirements (shares)		(18,000)
Repurchases of common stock, net of retirements	(2,592)	$ 0	0	(2,592)	0
Share-based compensation	3,321	$ 0	3,321	0	0
Issuance of shares under share-based compensation plans (shares)		375,000
Issuance of shares under share-based compensation plans	7,808	$ 1	7,807	0	0
Declaration of cash dividends	(15,011)	0	0	(15,011)	0
Other	(26)	0	0	0	(26)
Balance at Mar. 31, 2018	249,785	$ 41	437,878	(182,580)	(5,554)
Balance (in shares) at Mar. 31, 2018		40,569,000
Balance (in shares) at Dec. 31, 2017		40,212,000
Balance at Dec. 31, 2017	223,146	$ 40	426,750	(196,316)	(7,328)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	148,388
Foreign currency translation	(2,879)
Interest rate swaps, net of the change in taxes	1,378
Balance at Jun. 30, 2018	$ 313,801	$ 40	442,614	(119,998)	(8,855)
Balance (in shares) at Jun. 30, 2018	40,371,424	40,371,000
Balance (in shares) at Mar. 31, 2018		40,569,000
Balance at Mar. 31, 2018	$ 249,785	$ 41	437,878	(182,580)	(5,554)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	117,049	0	0	117,049	0
Foreign currency translation	(3,854)	0	0	0	(3,854)
Interest rate swaps, net of the change in taxes	554	$ 0	0	0	554
Repurchases of common stock, net of retirements (shares)		(259,000)
Repurchases of common stock, net of retirements	(36,284)	$ (1)	0	(36,283)	0
Share-based compensation	3,160	$ 0	3,160	0	0
Issuance of shares under share-based compensation plans (shares)		61,000
Issuance of shares under share-based compensation plans	1,575	$ 0	1,575	0	0
Declaration of cash dividends	(18,183)	0	0	(18,183)	0
Other	(1)	0	1	(1)	(1)
Balance at Jun. 30, 2018	$ 313,801	$ 40	442,614	(119,998)	(8,855)
Balance (in shares) at Jun. 30, 2018	40,371,424	40,371,000
Balance (in shares) at Dec. 31, 2018	39,506,067	39,506,000
Balance at Dec. 31, 2018	$ 223,590	$ 40	453,193	(218,646)	(10,997)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	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 shares under share-based compensation plans	7,071	$ 1	7,070	0	0
Declaration of cash dividends	(17,819)	0	0	(17,819)	0
Balance at Mar. 31, 2019	$ 224,877	$ 40	463,522	(227,633)	(11,052)
Balance (in shares) at Mar. 31, 2019		39,679,000
Balance (in shares) at Dec. 31, 2018	39,506,067	39,506,000
Balance at Dec. 31, 2018	$ 223,590	$ 40	453,193	(218,646)	(10,997)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net Income (loss)	164,027
Foreign currency translation	1,422
Interest rate swaps, net of the change in taxes	(1,509)
Balance at Jun. 30, 2019	$ 343,169	$ 40	472,390	(118,177)	(11,084)
Balance (in shares) at Jun. 30, 2019	39,897,898	39,898,000
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 (loss)	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 shares under share-based compensation plans	5,533	$ 0	5,533	0	0
Declaration of cash dividends	(21,934)	0	0	(21,934)	0
Balance at Jun. 30, 2019	$ 343,169	$ 40	$ 472,390	$ (118,177)	$ (11,084)
Balance (in shares) at Jun. 30, 2019	39,897,898	39,898,000