CONSOLIDATED STATEMENTS OF STOCKHOLDERS’ EQUITY - USD ($) $ in Thousands		Total	Common Stock [Member]	Additional Paid-In Capital [Member]	Retained Earnings (Deficit) [Member]	Treasury Stock [Member]
Balance at Dec. 31, 2015		$ 549,416	$ 48	$ 921,318	$ (371,950)	$ 0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock activity and shares exchanged for tax withholding		(1,113)	1	0		(1,114)
Stock-based compensation		9,455		9,455
Retirement of treasury stock		0		(1,114)		1,114
Exchange of senior notes for shares of common stock		74,400	10	74,390
Issuance of common stock, net of offering costs		109,763	15	109,748
Net Income (Loss)		(170,378)			(170,378)
Balance at Dec. 31, 2016		571,543	74	1,113,797	(542,328)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Cumulative effect of accounting change		(329)		180	(509)
Restricted stock activity and shares exchanged for tax withholding		(1,252)	1	0		(1,253)
Stock-based compensation		7,099		7,099
Retirement of treasury stock		0		(1,253)		1,253
Exchange of senior notes for shares of common stock		48,992	11	48,981
Issuance of common stock, net of offering costs		110,726	23	110,703
Net Income (Loss)		(138,225)			(138,225)
Balance at Dec. 31, 2017		598,554	109	1,279,507	(681,062)	0
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Restricted stock activity and shares exchanged for tax withholding		(1,534)	1	0		(1,535)
Stock-based compensation	[1]	9,858		9,858
Retirement of treasury stock		0		(1,535)		1,535
Issuance of common stock, merger		484,000	100	483,900
Net Income (Loss)		121,220			121,220
Balance at Dec. 31, 2018		$ 1,212,098	$ 210	$ 1,771,730	$ (559,842)	$ 0

[1] As of December 31, 2018, includes the modification of the 2016 Program and 2017 Program from performance-based liability awards to service-based equity awards. See Note 11 for additional information.