Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 9 months ended Sep. 30, 2016 - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]
Beginning Balances at Dec. 31, 2015	$ 620,554	$ 2,227	$ 1,829,082		$ (1,210,755)
Beginning Balance, shares at Dec. 31, 2015		222,674,270
Stock-based compensation	5,464		5,464
Shares of common stock issued in public offering, net of equity issuance costs	123,877	$ 375	123,502
Shares of common stock issued in public offering, net of equity issuance costs, shares		37,500,000
Issuance of restricted stock		$ 2	(2)
Issuance of restricted stock, shares		149,448
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings	(61)	$ 3	(3)	$ (61)
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings, shares		268,175
Net loss	(140,499)				(140,499)
Ending Balances at Sep. 30, 2016	$ 609,335	$ 2,607	$ 1,958,043	$ (61)	$ (1,351,254)
Ending Balance, shares at Sep. 30, 2016		260,591,893