Consolidated Statements of Stockholders' Equity - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-In Capital	Treasury Stock	Retained Deficit
Beginning balance (in shares) at Dec. 31, 2017		26,371,572		152,443,000
Beginning balance at Dec. 31, 2017	$ 338,653	$ 264	$ 439,517	$ (4,454)	$ (96,674)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of restricted stock (in shares)		272,510
Issuances of restricted stock	0	$ 2	(2)
Amortization of equity-classified share-based compensation	6,798		6,798
Treasury stock, net (in shares)				69,337,000
Treasury stock, net	(1,342)		(291)	$ (1,051)
Net loss	(30,531)				(30,531)
Ending balance (in shares) at Mar. 31, 2018		26,644,082		221,780,000
Ending balance at Mar. 31, 2018	313,578	$ 266	446,022	$ (5,505)	(127,205)
Beginning balance (in shares) at Dec. 31, 2018		26,990,034		242,322,000
Beginning balance at Dec. 31, 2018	219,428	$ 270	464,264	$ (3,835)	(241,271)
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Issuances of restricted stock (in shares)		277,865
Issuances of restricted stock	0	$ 3	(3)
Amortization of equity-classified share-based compensation	3,275		3,275
Treasury stock, net (in shares)				68,227,000
Treasury stock, net	(343)		(163)	$ (180)
Net loss	(27,476)				(27,476)
Ending balance (in shares) at Mar. 31, 2019		27,267,899		310,549,000
Ending balance at Mar. 31, 2019	$ 194,884	$ 273	$ 467,373	$ (4,015)	$ (268,747)