Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 6 months ended Jun. 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	3,701		3,701
Equity issuance costs	(277)		(277)
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		267,968
Repurchase of common stock, shares		(72,590)
Net loss	(113,698)				(113,698)
Ending Balances at Jun. 30, 2016	$ 510,219	$ 2,232	$ 1,832,501	$ (61)	$ (1,324,453)
Ending Balance, shares at Jun. 30, 2016		223,091,686