Equity, Capital and Other Interests Preferred (Details) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended		12 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Dec. 31, 2012
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 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		$ 50,000
Series K Preferred Stock [Member]
Class of Stock [Line Items]
Preferred Stock Preference Units Issued	1,000,000		1,000,000
Preferred Stock Preference Units Outstanding	1,000,000		1,000,000
Preferred Stock Preference Units Redemption Price Per Share Unit	$ 50.00		$ 50.00
Preferred Stock Preference Units Dividend Rate Percentage	8.29%	8.29%	8.29%
Preferred Stocks Preference Units Redemption Date	Dec. 10, 2026
Annual Dividend Per Preferred Share Preference Unit	$ 4.145
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		50,000
Preference Units	$ 50,000		$ 50,000