Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 3 months ended Mar. 31, 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	1,981		1,981
Equity issuance costs	(145)		(145)
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 common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings	(935)	$ 18	(18)	(935)
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings, shares		1,207,160
Net income (loss)	(2,626)				(2,626)
Ending Balances at Mar. 31, 2018	$ 660,649	$ 3,033	$ 2,059,418	$ (3,031)	$ (1,398,771)
Ending Balance, shares at Mar. 31, 2018		301,771,111