CONSOLIDATED STATEMENTS OF STOCKHOLDERS' DEFICIT - USD ($) $ in Thousands	Total	Common Stock	Common Stock Warrants	Additional Paid-in Capital	Accumulated Earnings (Deficit)
Beginning Balance at Dec. 31, 2014	$ 870,272	$ 4,686		$ 499,177	$ 366,409
Beginning Balance, Shares at Dec. 31, 2014		9,372,000
Stock-based compensation	8,149	$ 94		8,055
Stock-based compensation, Shares		188,000
Income tax withholdings related to equity awards	(526)	$ (8)		(518)
Income tax withholdings related to equity awards, Shares		(16,000)
Income taxes related to equity award vesting	(2,044)			(2,044)
Net loss	(1,047,109)				(1,047,109)
Ending Balance at Dec. 31, 2015	(171,258)	$ 4,772		504,670	(680,700)
Ending Balance, Shares at Dec. 31, 2015		9,544,000
Stock-based compensation	4,660	$ 116		4,544
Stock-based compensation, Shares		232,000
Income tax withholdings related to equity awards	(313)	$ (20)		(293)
Income tax withholdings related to equity awards, Shares		(41,000)
Common stock issued for debt conversion	1,639	$ 88		1,551
Common stock issued for debt conversion, Shares		176,000
Common stock issued in exchange for debt	13,603	$ 1,385		12,218
Common stock issued in exchange for debt, Shares		2,771,000
Common stock warrants issued	15,623		$ 15,623
Common stock warrants exercised	13	$ 628	(9,951)	9,336
Common stock warrants exercised, Shares		1,256,000
Stock issuance costs	(102)			(102)
Net loss	(135,134)				(135,134)
Ending Balance at Dec. 31, 2016	(271,269)	$ 6,969	5,672	531,924	(815,834)
Ending Balance, Shares at Dec. 31, 2016		13,938,000
Stock-based compensation	5,923	$ 225		5,698
Stock-based compensation, Shares		451,000
Income tax withholdings related to equity awards	(312)	$ (16)		(296)
Income tax withholdings related to equity awards, Shares		(34,000)
Common stock issued for debt conversion	7,789	$ 412		7,377
Common stock issued for debt conversion, Shares		826,000
Common stock warrants exercised	$ 2	$ 124	(2,115)	1,993
Common stock warrants exercised, Shares	1,502,255	247,000
Net loss	$ (111,405)				(111,405)
Ending Balance at Dec. 31, 2017	$ (369,272)	$ 7,714	$ 3,557	$ 546,696	$ (927,239)
Ending Balance, Shares at Dec. 31, 2017		15,428,000