CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified			12 Months Ended
	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2013 9.25% Series A Preferred Stock	Dec. 31, 2012 9.25% Series A Preferred Stock	Dec. 31, 2013 7.875% Series B Preferred Stock	Dec. 31, 2012 7.875% Series B Preferred Stock	Dec. 31, 2013 7.125% Series C Preferred Stock	Dec. 31, 2012 7.125% Series C Preferred Stock
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized	100,000,000	100,000,000
Preferred stock, shares issued			2,000,000	2,000,000	3,000,000	3,000,000	3,400,000	3,400,000
Preferred stock, shares outstanding			2,000,000	2,000,000	3,000,000	3,000,000	3,400,000	3,400,000
Preferred stock, liquidation preference (in dollars)			$ 50,398	$ 50,398	$ 75,324	$ 75,324	$ 85,522
Preferred stock, dividend rate (as a percent)			9.25%	9.25%	7.875%	7.875%	7.125%	7.125%
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized	450,000,000	450,000,000
Common stock, issued	85,402,408	46,159,652
Common stock, outstanding	85,402,408	46,159,652