CONDENSED CONSOLIDATED BALANCE SHEETS (USD $) In Thousands, unless otherwise specified	Mar. 31, 2013	Dec. 31, 2012
Real estate properties, at cost:
Land	$ 1,453,390	$ 1,453,399
Buildings, improvements and equipment	5,498,521	5,445,710
Total real estate properties, gross	6,951,911	6,899,109
Accumulated depreciation	(1,601,342)	(1,551,160)
Total real estate properties, net	5,350,569	5,347,949
Cash and cash equivalents	18,043	20,049
Restricted cash (FF&E reserve escrow)	37,930	40,744
Other assets, net	252,688	226,383
Total assets	5,659,230	5,635,125
LIABILITIES AND SHAREHOLDERS' EQUITY
Unsecured revolving credit facility	10,000	320,000
Unsecured term loan	400,000	400,000
Senior notes, net of discounts	1,994,372	1,993,880
Convertible senior notes, net of discount	8,478	8,478
Security deposits	20,660	26,577
Accounts payable and other liabilities	106,776	132,032
Due to related persons	11,297	13,696
Dividends payable	6,664	6,664
Total liabilities	2,558,247	2,901,327
Commitments and contingencies
Preferred shares of beneficial interest, no par value, 100,000,000 shares authorized:
Common shares of beneficial interest, $.01 par value; 200,000,000 shares authorized; 139,737,424 and 123,637,424 shares issued and outstanding, respectively	1,397	1,236
Additional paid in capital	3,851,456	3,458,144
Cumulative net income	2,412,382	2,384,876
Cumulative other comprehensive income	15,183	2,770
Cumulative preferred distributions	(261,523)	(253,426)
Cumulative common distributions	(3,359,892)	(3,301,782)
Total shareholders' equity	3,100,983	2,733,798
Total liabilities and shareholders' equity	5,659,230	5,635,125
Series C
Preferred shares of beneficial interest, no par value, 100,000,000 shares authorized:
Preferred shares	161,873	161,873
Series D
Preferred shares of beneficial interest, no par value, 100,000,000 shares authorized:
Preferred shares	$ 280,107	$ 280,107