Condensed Consolidated Statements of Stockholders' Equity (Unaudited) - 6 months ended Jun. 30, 2017 - USD ($) $ in Thousands	Total	Common Stock [Member]	Additional Paid-in Capital [Member]	Treasury Stock [Member]	Accumulated Deficit [Member]
Beginning Balances at Dec. 31, 2016	$ 556,607	$ 2,607	$ 1,958,731	$ (61)	$ (1,404,670)
Beginning Balance, shares at Dec. 31, 2016		260,591,893
Stock-based compensation	4,429		4,429
Equity issuance costs	(40)		(40)
Issuance of restricted stock		$ 2	(2)
Issuance of restricted stock, shares		153,192
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings	(2,032)	$ 28	(28)	(2,032)
Issuance of common stock upon vesting of equity-based compensation awards, net of shares withheld for income tax withholdings, shares		1,993,357
Net income	38,341				38,341
Ending Balances at Jun. 30, 2017	$ 597,305	$ 2,637	$ 1,963,090	$ (2,093)	$ (1,366,329)
Ending Balance, shares at Jun. 30, 2017		262,738,442