Condensed Consolidated Statements of Equity (unaudited) - USD ($) $ in Thousands	Total	Common Stock	Common Stock - Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Treasury Stock
Beginning Balance (in shares) at Dec. 31, 2018		37,318,942
Beginning Balance at Dec. 31, 2018	$ 765,253	$ 5	$ 451,427	$ 427,244	$ (1,656)	$ (111,767)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of restricted stock units to common stock (net of shares of treasury stock purchased) (in shares)		283,339
Conversion of restricted stock units to common stock (net of shares of treasury stock purchased)	(2,760)					(2,760)
Settlement of stock appreciation rights in common stock (net of shares of treasury stock purchased) (in shares)		16,937
Settlement of stock appreciation rights in common stock (net of shares of treasury stock purchased)	(171)		(12)			(159)
Partial termination of capped call options (in shares)		(1,087)
Termination of capped call options	0		30			(30)
Convertible debt extinguishment impact (net of tax impact)	(152)		(152)
Stock compensation expense	1,353		1,353
Other comprehensive income (loss)	(362)				(362)
Net income (loss)	(43,404)			(43,404)
Ending Balance (in shares) at Mar. 31, 2019		37,618,131
Ending Balance at Mar. 31, 2019	713,241	$ 5	452,646	377,324	(2,018)	(114,716)
Beginning Balance (in shares) at Dec. 31, 2019		38,967,079
Beginning Balance at Dec. 31, 2019	1,131,906	$ 5	438,591	800,792	(1,994)	(105,488)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Conversion of restricted stock units to common stock (net of shares of treasury stock purchased) (in shares)		38,144
Conversion of restricted stock units to common stock (net of shares of treasury stock purchased)	(578)					(578)
Settlement of stock appreciation rights in common stock (net of shares of treasury stock purchased) (in shares)		16,704
Settlement of stock appreciation rights in common stock (net of shares of treasury stock purchased)	(245)		(5)			(240)
Convertible debt extinguishment impact (net of tax impact)	(17,829)		(17,829)
Stock compensation expense	1,367		1,367
Other comprehensive income (loss)	(551)				(551)
Net income (loss)	76,853			76,853
Ending Balance (in shares) at Mar. 31, 2020		39,021,927
Ending Balance at Mar. 31, 2020	$ 1,190,923	$ 5	$ 422,124	$ 877,645	$ (2,545)	$ (106,306)