Stockholder's Equity (Details Textuals)	3 Months Ended
	Mar. 31, 2012 $ / shares shares	Mar. 31, 2011 $ / shares shares	Dec. 31, 2010 shares
Series H Preferred Stock [Member]
Preferred Stock [Line Items]
Preferred stock, shares issued			349,854
Preferred stock balance issued average rate			0.06
Series I Preferred Stock [Member]
Preferred Stock [Line Items]
Preferred stock, shares issued		14,375,000
Preferred stock balance issued average rate		0.065
Equivalent Number Of Common Stock On Conversion Of Preferred Shares		0.846
Initial conversion Price | $ / shares		$ 59.1
Liquidation value per preferred share | $ / shares		$ 50
Series J Preferred Stock [Member]
Preferred Stock [Line Items]
Preferred stock, shares issued	11,500,000
Preferred stock balance issued average rate	0.065
Redemption date, preferred stock	Mar. 07, 2017
Initial conversion Price | $ / shares	$ 25
Preferred Stock Redemption Announcement Date	Feb. 02, 2017