Net (Loss) Income Per Common Share- Calculation of Basic Net (Loss) Income Per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended			6 Months Ended		12 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Mar. 31, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Numerator for basic and diluted net (loss) income per share:
Net (loss) income	$ (73,483)	$ 17,322		$ (67,982)	$ 13,942	$ 3,070
Preferred deemed dividend			$ (9,455)		(9,455)
Series B preferred stock dividends	(4,500)			(8,748)
Net (loss) income attributable to common shareholders	$ (77,983)	$ 17,322		$ (76,730)	$ 4,487
Denominator for basic net (loss) income per share:
Weighted-average shares outstanding	204,368,982	202,164,035		203,361,710	202,071,761
Weighted-average unvested restricted shares outstanding	(2,481,891)	(1,164,554)		(1,842,836)	(1,333,534)
Denominator for basic net (loss) income per share:	201,887,091	200,999,481		201,518,874	200,738,227
Basic net (loss) income per share attributable to common shareholders	$ (0.39)	$ 0.09		$ (0.38)	$ 0.02