Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 6 months ended Jun. 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	3,960		3,960
Equity issuance costs	(170)		(170)
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	(1,140)	$ 23	(23)	(1,140)
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings, shares		(1,528,934)
Net income (loss)	(21,660)				(21,660)
Ending Balances at Jun. 30, 2018	$ 643,364	$ 3,040	$ 2,061,365	$ (3,236)	$ (1,417,805)
Ending Balance, shares at Jun. 30, 2018		302,325,028