Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) - USD ($) $ in Thousands	6 Months Ended	12 Months Ended
	Jun. 30, 2015	Dec. 31, 2014
Allowance for doubtful accounts	$ 6,192	$ 7,680
Preferred Shares of Beneficial Interest - par value, $.03 per share; shares authorized: 10,000
Preferred Shares of Beneficial Interest; par value per share	$ 0.03	$ 0.03
Preferred Shares of Beneficial Interest; shares authorized	10,000,000	10,000,000
Common Shares of Beneficial Interest - par value, $.03 per share; shares authorized: 275,000; shares issued and outstanding: 123,934 in 2015 and 122,489 in 2014
Common Shares of Beneficial Interest; par value per share	$ 0.03	$ 0.03
Common Shares of Beneficial Interest - shares authorized	275,000,000	275,000,000
Common Shares of Beneficial Interest - shares issued	123,934,000	122,489,000
Common Shares of Beneficial Interest - shares outstanding	123,934,000	122,489,000
6.5% Series F Preferred Shares [Member]
Preferred Shares of Beneficial Interest - par value, $.03 per share; shares authorized: 10,000
Preferred Shares of Beneficial Interest; shares issued	140,000	140,000
Preferred Shares of Beneficial Interest; shares outstanding	0	60,000
Preferred Shares of Beneficial Interest; liquidation preference		$ 150,000
Preferred Shares of Beneficial Interest; dividend percentage	6.50%	6.50%