Consolidated Statements of Shareholders' Deficit Statement - USD ($) $ in Thousands		Total	Common Stock, Par Value $0.01 per share	Additional Paid-in- Capital	Accumulated Other Comprehensive Income (Loss)	Treasury Stock	Retained Earnings
Beginning balance (in shares) at Dec. 31, 2017			56,679,968
Beginning balance at Dec. 31, 2017		$ (258,601)	$ 951	$ 182,448	$ (4,699)	$ (1,064,573)	$ 627,272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		25,086					25,086
Other comprehensive income		1,070			1,070
Share based payment activity (in shares)			498,510
Share based payment activity		26,579		13,203		13,376
Dividends declared ($0.215 per share)		(12,182)					(12,182)
Treasury purchases (in shares)			(517,839)
Treasury purchases		(41,869)				(41,869)
Ending balance at Mar. 31, 2018		(259,917)	$ 951	195,651	(3,629)	(1,093,066)	640,176
Ending balance (in shares) at Mar. 31, 2018			56,660,639
Beginning balance (in shares) at Dec. 31, 2017			56,679,968
Beginning balance at Dec. 31, 2017		(258,601)	$ 951	182,448	(4,699)	(1,064,573)	627,272
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		104,925
Other comprehensive income		(583)
Ending balance at Jun. 30, 2018		(203,952)	$ 951	204,899	(5,282)	(1,112,376)	707,856
Ending balance (in shares) at Jun. 30, 2018			56,633,606
Beginning balance (in shares) at Mar. 31, 2018			56,660,639
Beginning balance at Mar. 31, 2018		(259,917)	$ 951	195,651	(3,629)	(1,093,066)	640,176
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		79,839					79,839
Other comprehensive income		(1,653)			(1,653)
Share based payment activity (in shares)			332,657
Share based payment activity		18,642		9,248		9,394
Dividends declared ($0.215 per share)		(12,159)					(12,159)
Treasury purchases (in shares)			(359,690)
Treasury purchases		(28,704)				(28,704)
Ending balance at Jun. 30, 2018		$ (203,952)	$ 951	204,899	(5,282)	(1,112,376)	707,856
Ending balance (in shares) at Jun. 30, 2018			56,633,606
Beginning balance (in shares) at Dec. 31, 2018		55,679,207	55,679,207
Beginning balance at Dec. 31, 2018		$ (183,772)	$ 951	213,170	(5,446)	(1,187,625)	795,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		30,081					30,081
Other comprehensive income		8			8
Share based payment activity (in shares)			408,545
Share based payment activity		12,920		3,214		9,706
Dividends declared ($0.215 per share)		(12,149)					(12,149)
Treasury purchases (in shares)			(414,077)
Treasury purchases		(31,951)				(31,951)
Other	[1]	(614)					(614)
Ending balance at Mar. 31, 2019		$ (185,477)	$ 951	216,384	(5,438)	(1,209,870)	812,496
Ending balance (in shares) at Mar. 31, 2019			55,673,675
Beginning balance (in shares) at Dec. 31, 2018		55,679,207	55,679,207
Beginning balance at Dec. 31, 2018		$ (183,772)	$ 951	213,170	(5,446)	(1,187,625)	795,178
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		104,470
Other comprehensive income		$ (228)
Treasury purchases (in shares)		(476,833)
Ending balance at Jun. 30, 2019		$ (122,660)	$ 951	222,394	(5,674)	(1,215,254)	874,923
Ending balance (in shares) at Jun. 30, 2019		55,696,356	55,696,356
Beginning balance (in shares) at Mar. 31, 2019			55,673,675
Beginning balance at Mar. 31, 2019		$ (185,477)	$ 951	216,384	(5,438)	(1,209,870)	812,496
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net income		74,389					74,389
Other comprehensive income		(236)			(236)
Share based payment activity (in shares)			151,856
Share based payment activity		11,112		6,010		5,102
Dividends declared ($0.215 per share)		$ (11,962)					(11,962)
Treasury purchases (in shares)		(122,237)	(129,175)
Treasury purchases		$ (10,486)				(10,486)
Ending balance at Jun. 30, 2019		$ (122,660)	$ 951	$ 222,394	$ (5,674)	$ (1,215,254)	$ 874,923
Ending balance (in shares) at Jun. 30, 2019		55,696,356	55,696,356

[1] Impact of adoption of Financial Accounting Standards Board ("FASB") Accounting Standards Update (“ASU”) No. 2014-09, Revenue From Contracts with Customers (Topic 606) and subsequent amendments to the initial guidance ("Topic 606") related to a foreign joint venture accounted for as an equity method investment.