Equity (Details Textual) (USD $) In Millions, except Share data, unless otherwise specified	6 Months Ended
	Jun. 30, 2014	Dec. 31, 2013
Common Stock Disclosures [Abstract]
Common shares of beneficial interest, shares authorized	500,000,000	500,000,000
Common shares of beneficial interest, par value	$ 0.01	$ 0.01
Preferred Stock Disclosures [Abstract]
Preferred shares of beneficial interest, shares authorized	100,000,000	100,000,000
Preferred shares of beneficial interest, par value	$ 0.01	$ 0.01
Preferred Stock, Shares Outstanding	13,000,000	13,000,000
Preferred shares of beneficial interest, redemption price per share	$ 25.00
LTIP Units Disclosures [Abstract]
Operating Partnership outstanding	607,991	607,991
LTIP units, vested	195,290
6.50% Series C [Member]
Preferred Stock Disclosures [Abstract]
Preferred Stock, Shares Outstanding	4,000,000	4,000,000
Preferred Stock, Dividend Rate, Percentage	6.50%
Share cap on each preferred shares	2.0325
7.875% Series A [Member]
Preferred Stock Disclosures [Abstract]
Preferred Stock, Shares Outstanding	5,600,000	5,600,000
Preferred Stock, Dividend Rate, Percentage	7.875%
Share cap on each preferred shares	2.3234
8.00% Series B [Member]
Preferred Stock Disclosures [Abstract]
Preferred Stock, Shares Outstanding	3,400,000	3,400,000
Preferred Stock, Dividend Rate, Percentage	8.00%
Share cap on each preferred shares	3.4483
ATMProgram [Member]
Common Stock Disclosures [Abstract]
Mar 2014 Shelf Registration Stmt Maximum Amount	$ 175.0
Sept 2012 Shelf Registration Stmt Maximum Amount	170.0
Amount Available under ATM Program	$ 175.0