Equity, Capital and Other Interests Preferred (Details) (USD $)	9 Months Ended			9 Months Ended	12 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011	Sep. 30, 2012 Series K Preferred Stock [Member]	Dec. 31, 2011 Series K Preferred Stock [Member]	Sep. 30, 2012 Series N Preferred Stock [Member]	Dec. 31, 2011 Series N Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock, Shares Authorized	100,000,000		100,000,000
Preferred Stock, Par or Stated Value Per Share	$ 0.01		$ 0.01
Preferred Stock Preference Units Issued				1,000,000	1,000,000	0	600,000
Preferred Stock Preference Units Outstanding				1,000,000	1,000,000	0	600,000
Preferred Stock Preference Units Redemption Price Per Share Unit				$ 50.00	$ 50.00	$ 250.00	$ 250.00
Preferred Stock Preference Units Dividend Rate Percentage				8.29%	8.29%	6.48%	6.48%
Preferred Stocks Preference Units Redemption Date				Dec. 10, 2026		Jun. 19, 2008
Annual Dividend Per Preferred Share Preference Unit				$ 4.145		$ 16.20
Preferred Shares of beneficial interest, $0.01 par value; 100,000,000 shares authorized; 1,000,000 shares issued and outstanding as of September 30, 2012 and 1,600,000 shares issued and outstanding as of December 31, 2011	$ 50,000,000		$ 200,000,000	$ 50,000,000	$ 50,000,000	$ 0	$ 150,000,000
Preference Units				50,000,000	50,000,000	0	150,000,000
Annual Dividend Per Depositary Share	$ 1.62
Redemption of Preferred Shares Preference Units	150,000,000	0
Write Off Issuance Costs	$ 5,100,000