Earnings per Share (Details) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Basic earnings (loss) per share:
Net income (loss)	$ (83,892)	$ 77,891	$ (93,871)	$ 82,212
Dividends declared on preferred stock	(5,480)	(5,480)	(16,441)	(16,441)
Net income (loss) available to common shareholders	$ (89,372)	$ 72,411	$ (110,312)	$ 65,771
Weighted average shares	96,545,913	96,563,132	96,705,682	96,561,446
Basic earnings (loss) per share	$ (0.93)	$ 0.75	$ (1.14)	$ 0.68
Diluted earnings (loss) per share:
Net income (loss)	$ (83,892)	$ 77,891	$ (93,871)	$ 82,212
Dividends declared on preferred stock	(5,480)	(5,480)	(16,441)	(16,441)
Net income (loss) available to common shareholders	$ (89,372)	$ 72,411	$ (110,312)	$ 65,771
Weighted average shares	96,545,913	96,563,132	96,705,682	96,561,446
Diluted weighted average shares	96,545,913	96,563,132	96,705,682	96,561,446
Diluted earnings (loss) per share	$ (0.93)	$ 0.75	$ (1.14)	$ 0.68