Consolidated Balance Sheets (Parenthetical) (USD $)			12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2011	Dec. 31, 2010	Dec. 31, 2010 Series D [Member]	Sep. 30, 2011 $25 Par Preferred Stock [Member]	Dec. 31, 2010 $25 Par Preferred Stock [Member]
Stockholders' equity:
Preferred Stock, Par Value			$ 1	$ 25	$ 25
Preferred Stock, Dividend Rate			5.125%	4.00%	4.00%
Preferred Stock, Shares Authorized			210,000	840,000	840,000
Preferred Stock, Shares Issued			210,000	649,736	649,736
Preferred Stock, Shares Outstanding			209,995	242,170	242,170
Cumulative perpetual preferred stock liquidation preference			$ 1,000
Common Stock, Par Value	$ 0.01	$ 0.01
Common Stock, Shares Authorized	400,000,000	400,000,000
Common Stock, Shares Issued	123,352,185	116,352,298
Common Stock, Shares Outstanding	109,844,141	102,648,845