Equity and Stock Based-Compensation (Details 6) (USD $)	12 Months Ended
	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Common Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax status on common stock dividends per share declared	$ 0.180000	$ 0.360000	$ 0.740000
Tax Status of Unrecaptured Section 1250 Gain (A)	$ 0.042574	$ 0.073937
Series A Preferred Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax Status on Preferred Stock Dividends Per Share Declared	$ 1.937500	$ 1.937500	$ 1.937500
Tax Status of Unrecaptured Section 1250 Gain (A)	$ 0.458393	$ 0.399714
Series B Preferred Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax Status on Preferred Stock Dividends Per Share Declared	$ 1.875000	$ 1.875000	$ 1.875000
Unrecaptured Section 1250 Gain	$ 0.443606	$ 0.386819
Ordinary Dividends [Member] | Common Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax status on common stock dividends per share declared	$ 0.067853	$ 0.059447	$ 0.549006
Ordinary Dividends [Member] | Series A Preferred Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax Status on Preferred Stock Dividends Per Share Declared	$ 0.730053	$ 0.315868	$ 1.290594
Ordinary Dividends [Member] | Series B Preferred Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax Status on Preferred Stock Dividends Per Share Declared	$ 0.706502	$ 0.305678	$ 1.248962
Long term capital gain [Member] | Common Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax status on common stock dividends per share declared	$ 0.112147	$ 0.300553	$ 0.190994
Long term capital gain [Member] | Series A Preferred Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax Status on Preferred Stock Dividends Per Share Declared	$ 1.207447	$ 1.621632	$ 0.646906
Long term capital gain [Member] | Series B Preferred Stock [Member]
Summary of Components of the taxability of the Company's dividends [Abstract]
Tax Status on Preferred Stock Dividends Per Share Declared	$ 1.168498	$ 1.569322	$ 0.626038