Condensed Consolidated Balance Sheets (Unaudited) (Parenthetical) (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended	12 Months Ended
Mar. 31, 2015	Dec. 31, 2014
Allowance for doubtful accounts	$ 6,519	$ 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	10,000,000us-gaap_PreferredStockSharesAuthorized	10,000,000us-gaap_PreferredStockSharesAuthorized
Common Shares of Beneficial Interest - par value, $.03 per share; shares authorized: 275,000; shares issued and outstanding: 123,585 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	275,000,000us-gaap_CommonStockSharesAuthorized	275,000,000us-gaap_CommonStockSharesAuthorized
Common Shares of Beneficial Interest - shares issued	123,585,000us-gaap_CommonStockSharesIssued	122,489,000us-gaap_CommonStockSharesIssued
Common Shares of Beneficial Interest - shares outstanding	123,585,000us-gaap_CommonStockSharesOutstanding	122,489,000us-gaap_CommonStockSharesOutstanding
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	60,000	60,000
Preferred Shares of Beneficial Interest; liquidation preference	$ 150,000	$ 150,000
Preferred Shares of Beneficial Interest; dividend percentage	6.50%	6.50%

The valuation allowance as of the balance sheet date to reduce the gross amount of receivables to estimated net realizable value, which would be presented in parentheses on the face of the balance sheet.

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