Consolidated Statements of Stockholders' Equity (Deficit) - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Accumulated Deficit) [Member]	Accumulated Other Comprehensive Income [Member]
Beginning balance, shares at Dec. 31, 2015	35,573,405
Beginning balance at Dec. 31, 2015	$ 804,676	$ 355	$ 591,454	$ 212,054	$ 813
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(833,858)			(833,858)
Other comprehensive income, net of tax	120				120
Share-based compensation	6,568		6,568
Tax shortfall on share-based compensation	$ (1,393)		(1,393)
Share-based compensation issuances, net, shares	817,724
Share-based compensation issuances, net	$ (553)	9	(562)
Ending balance, shares at Dec. 31, 2016	36,391,129
Ending balance at Dec. 31, 2016	$ (24,440)	364	596,067	(621,804)	933
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Net loss	(426,899)			(426,899)
Other comprehensive income, net of tax	10				10
Reclassification adjustment related to adoption of accounting guidance	0			(114)	114
Share-based compensation	$ 2,212		2,212
Share-based compensation issuances, net, shares	982,487
Share-based compensation issuances, net	$ (76)	10	(86)
Ending balance, shares at Dec. 31, 2017	37,373,616
Ending balance at Dec. 31, 2017	$ (449,193)	$ 374	$ 598,193	$ (1,048,817)	$ 1,057