Stockholder's Equity (Details Textuals) (USD $)	3 Months Ended	6 Months Ended			6 Months Ended		3 Months Ended	6 Months Ended
	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010	Jun. 30, 2011 Series I cumulative convertible perpetual preferred stock [Member]	Jun. 30, 2010 Series G Preferred Stock [Member]	Jun. 30, 2011 Other Equity	Jun. 30, 2011 Other Equity	Jun. 30, 2010 Other Equity
Stockholders Equity [Line Items]
Cumulative Convertible Preferred Stock, Converted Into common Stock						76,841
Common stock issued on conversion of preferred stock						54,990
Cumulative Convertible Preferred Stock, Outstanding		25,724,854		11,349,854		322,872
Cumulative convertible perpetual preferred stock issued					14,375,000
Liquidation value per preferred share					$ 50.00
Preferred stock dividend percentage					6.50%	7.50%
Equivalent Number Of Common Stock On Conversion Of Preferred Shares		0.8460
Initial conversion price		$ 59.10
Other equity	$ 221,000	$ 1,651,000	$ 1,194,000				$ 612,000	$ 1,651,000	$ 1,194,000