Equity and Stock-Based Compensation (Tax Status of Dividends) (Details) (USD $)	12 Months Ended
	Dec. 31, 2012		Dec. 31, 2011		Dec. 31, 2010
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		$ 0.180000		$ 0.360000
Tax Status of Unrecaptured Section 1250 Gain (A)	$ 0.055276	[1]	$ 0.042574	[1]	$ 0.073937	[1]
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)	$ 0.595280	[1]	$ 0.458393	[1]	$ 0.399714	[1]
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	$ 0.576078	[1]	$ 0.443606	[1]	$ 0.386819	[1]
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	$ 0.124724		$ 0.067853		$ 0.059447
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	$ 1.342220		$ 0.730053		$ 0.315868
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	$ 1.298222		$ 0.706502		$ 0.305678
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	$ 0.055276		$ 0.112147		$ 0.300553
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	$ 0.595280		$ 1.207447		$ 1.621632
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	$ 0.576078		$ 1.168498		$ 1.569322

[1] Represents a portion of the dividend allocated to long-term capital gain.