CONSOLIDATED BALANCE SHEETS (Parenthetical) (USD $)	Mar. 31, 2015	Dec. 31, 2014
Tenant and other receivables, allowance for doubtful accounts	$ 12,774,000	$ 13,123,000
Intangible assets, accumulated amortization	11,974,000	14,506,000
Common stock, par value	$ 1.00	$ 1.00
Common stock, shares authorized	200,000,000us-gaap_CommonStockSharesAuthorized	200,000,000us-gaap_CommonStockSharesAuthorized
Common stock, shares issued	68,741,000us-gaap_CommonStockSharesIssued	68,293,000us-gaap_CommonStockSharesIssued
Common stock, shares outstanding	68,741,000us-gaap_CommonStockSharesOutstanding	68,293,000us-gaap_CommonStockSharesOutstanding
Series A Preferred Shares [Member]
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, authorized	25,000,000	25,000,000
Preferred shares, issued	4,600,000	4,600,000
Preferred shares, outstanding	4,600,000	4,600,000
Liquidation preference	115,000,000	115,000,000
Series B Preferred Shares [Member]
Preferred shares, par value	$ 0.01	$ 0.01
Preferred shares, authorized	25,000,000	25,000,000
Preferred shares, issued	3,450,000	3,450,000
Preferred shares, outstanding	3,450,000	3,450,000
Liquidation preference	$ 86,250,000	$ 86,250,000

A valuation allowance for trade and other receivables due to an Entity within one year (or the normal operating cycle, whichever is longer) that are expected to be uncollectible.

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