Net (Loss) Income Per Common Share - Calculation of Diluted Net Income (Loss) Per Share Attributable to Common Stockholders (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended												12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2014	Sep. 30, 2014	Jun. 30, 2014	Mar. 31, 2014	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Numerator for basic net income (loss) per share:
Net income (loss)													$ 201,700	$ (61,833)	$ 3,070
Less: Series B preferred stock dividends													(18,000)	(17,748)
Less: Preferred deemed dividend															(9,455)
Less: Net income attributed to participating securities													(112,115)
Diluted net income (loss) attributable to common stockholders													$ 71,585	$ (79,581)	$ (6,385)
Denominator for diluted net income (loss) per share:
Weighted-average shares outstanding													206,291,857	204,776,405	202,208,619
Weighted-average unvested restricted shares outstanding													(4,020,970)	(3,029,792)	(1,338,691)
Effect of dilutive potential shares													33,135,473
Denominator for diluted net income (loss) per share:													235,406,360	201,746,613	200,869,928
Diluted net income (loss) per share attributable to common shareholders	$ 0.23	$ (0.10)	$ 0.03	$ 0.10	$ 0.01	$ (0.04)	$ (0.39)	$ 0.00	$ (0.05)	$ (0.01)	$ 0.07	$ (0.06)	$ 0.30	$ (0.39)	$ (0.03)