Basic and Diluted Per Share (Details) (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income applicable to common shares	$ (71,134)	$ 12,039	$ (69,597)	$ 20,276
Weighted average number of common shares outstanding	156,910	155,631	156,689	155,587
Effect of dilutive stock awards and convertible preferred stock	0	879	0	942
Effect of convertible preferred stock	0	6,065	0	6,065
Weighted average number of diluted common shares outstanding	156,910	162,575	156,689	162,594
Basic net income per share	$ (0.45)	$ 0.08	$ (0.44)	$ 0.13
Diluted net income per share	$ (0.45)	$ 0.08	$ (0.44)	$ 0.13
Series D Preferred Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Income impact of assumed Series D Preferred Stock conversion	0	338	0	676
Net Income after Assumed Preferred Stock Conversion	$ (71,134)	$ 12,377	$ (69,597)	$ 20,952