Condensed Consolidated Balance Sheets (Parenthetical) (USD $) In Thousands, except Per Share data, unless otherwise specified	9 Months Ended	12 Months Ended
	Sep. 30, 2014	Dec. 31, 2013
Allowance for doubtful accounts	$ 7,951	$ 9,386
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	10,000
Common Shares of Beneficial Interest - par value, $.03 per share; shares authorized: 275,000; shares issued and outstanding: 122,267 in 2014 and 121,949 in 2013
Common Shares of Beneficial Interest; par value per share	$ 0.03	$ 0.03
Common Shares of Beneficial Interest; shares authorized	275,000	275,000
Common Shares of Beneficial Interest; shares issued	122,267	121,949
Common Shares of Beneficial Interest; shares outstanding	122,267	121,949
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	140
Preferred Shares of Beneficial Interest; shares outstanding	60	60
Preferred Shares of Beneficial Interest; liquidation preference	$ 150,000	$ 150,000
Preferred Shares of Beneficial Interest; dividend percentage	6.50%	6.50%