Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Basic earnings (loss) per share:
Net income (loss)	$ (12,477)	$ 70,739	$ 4,321	$ 137,978
Less preferred stock dividends	(5,481)	(5,480)	(10,961)	(10,960)
Net income (loss) available to common shareholders	(17,958)	65,259	(6,640)	127,018
Weighted average shares	96,515,599	98,830,054	96,560,590	98,828,827
Basic earnings (loss) per share	$ (0.19)	$ 0.66	$ (0.07)	$ 1.29
Diluted earnings (loss) per share:
Net income (loss)	(12,477)	70,739	4,321	137,978
Less preferred stock dividends	(5,481)	(5,480)	(10,961)	(10,960)
Net income (loss) available to common shareholders	$ (17,958)	$ 65,259	$ (6,640)	$ 127,018
Weighted average shares	96,515,599	98,830,054	96,560,590	98,828,827
Potential dilutive shares from exercise of stock options
Diluted weighted average shares	96,515,599	98,830,054	96,560,590	98,828,827
Diluted earnings (loss) per share	$ (0.19)	$ 0.66	$ (0.07)	$ 1.29