Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 9 months ended Sep. 30, 2018 - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]
Beginning Balances at Dec. 31, 2017	$ 572,354	$ 2,637	$ 1,967,958	$ (2,096)	$ (1,396,145)
Beginning Balance, shares at Dec. 31, 2017		262,740,355
Stock-based compensation	6,131		6,131
Equity issuance costs	(307)		(307)
Shares of common stock issued in asset acquisition, net of equity issuance costs	90,020	$ 378	89,642
Shares of common stock issued in asset acquisition, net of equity issuance costs, shares		37,823,596
Issuance of restricted stock		$ 2	(2)
Issuance of restricted stock, shares		232,143
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings	(1,261)	$ 26	(26)	(1,261)
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings, shares		(1,739,844)
Net income (loss)	(17,662)				(17,662)
Ending Balances at Sep. 30, 2018	$ 649,275	$ 3,043	$ 2,063,396	$ (3,357)	$ (1,413,807)
Ending Balance, shares at Sep. 30, 2018		302,535,938