Earnings per Share (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Basic earnings (loss) per share:
Net income (loss)	$ 77,891	$ (262,146)	$ 82,212	$ (124,168)
Less preferred stock dividends	(5,480)	(5,481)	(16,441)	(16,441)
Net income (loss) available to common shareholders	72,411	(267,627)	65,771	(140,609)
Weighted average shares	96,563,132	98,318,205	96,561,446	98,656,750
Basic earnings (loss) per share	$ 0.75	$ (2.72)	$ 0.68	$ (1.43)
Diluted earnings (loss) per share:
Net income (loss)	77,891	(262,146)	82,212	(124,168)
Less preferred stock dividends	(5,480)	(5,481)	(16,441)	(16,441)
Net income (loss) available to common shareholders	$ 72,411	$ (267,627)	$ 65,771	$ (140,609)
Weighted average shares	96,563,132	98,318,205	96,561,446	98,656,750
Potential dilutive shares from exercise of stock options	0	0	0	0
Diluted weighted average shares	96,563,132	98,318,205	96,561,446	98,656,750
Diluted earnings (loss) per share	$ 0.75	$ (2.72)	$ 0.68	$ (1.43)