Consolidated Statements of Changes in Redeemable Convertible Preferred Stock and Stockholders' Equity - USD ($) $ in Thousands	Total	Convertible Series A Preferred Stock [Member]	Series B Redeemable Convertible Preferred Stock [Member]	Common Stock [Member]	Additional Paid-In Capital [Member]	(Accumulated deficit) retained earnings [Member]
Beginning Balance at Dec. 31, 2014	$ 88,230			$ 2	$ 106,628	$ (18,400)
Beginning Balance, Shares at Dec. 31, 2014		1,000,000		202,343,245
Net income (loss)	(61,833)					(61,833)
Issuance of redeemable convertible series B preferred stock, net of offering costs			$ 502,213
Issuance of redeemable convertible series B preferred stock, net of offering costs, Shares			600,000
Redeemable convertible Series B preferred stock dividends	(17,748)		$ (17,000)			(17,748)
Issuance of common stock under restricted stock compensation arrangement, Shares				3,824,790
Equity-based compensation	1,129				1,129
Ending Balance at Dec. 31, 2015	9,778			$ 2	107,757	(97,981)
Ending Balance, Shares at Dec. 31, 2015		1,000,000		206,168,035
Preferred Stock Ending Balance ,Shares at Dec. 31, 2015			600,000
Preferred Stock Value, Ending Balance at Dec. 31, 2015			$ 502,213
Net income (loss)	201,700					201,700
Redeemable convertible Series B preferred stock dividends	(18,000)		$ (18,000)			(18,000)
Issuance of common stock under restricted stock compensation arrangement, Shares				212,765
Equity-based compensation	658				658
Ending Balance at Dec. 31, 2016	194,136			$ 2	108,415	85,719
Ending Balance, Shares at Dec. 31, 2016		1,000,000		206,380,800
Preferred Stock Ending Balance ,Shares at Dec. 31, 2016			600,000
Preferred Stock Value, Ending Balance at Dec. 31, 2016			$ 502,213
Net income (loss)	25,882					25,882
Redeemable convertible Series B preferred stock dividends	(18,050)		(18,000)			(18,050)
Reduction of accrued fees incurred relating to Series B preferred stock issuance			$ 1,500
Reclassification of derivative asset	(108,893)				(108,893)
Issuance of common stock under restricted stock compensation arrangement, Shares				333,332
Equity-based compensation	517				517
Ending Balance at Dec. 31, 2017	$ 93,592			$ 2	$ 39	$ 93,551
Ending Balance, Shares at Dec. 31, 2017		1,000,000		206,714,132
Preferred Stock Ending Balance ,Shares at Dec. 31, 2017			600,000
Preferred Stock Value, Ending Balance at Dec. 31, 2017			$ 503,713