Investments In and Advances To Affiliates (Details) (USD $)	3 Months Ended
	Mar. 31, 2014	Mar. 31, 2013
Income Statements:
Rental and other revenues	$ 12,434,000	$ 23,516,000
Expenses:
Rental property and other expenses	6,217,000	11,209,000
Depreciation and amortization	3,489,000	6,146,000
Impairments of real estate assets	0	4,790,000
Interest expense	2,211,000	4,739,000
Total expenses	11,917,000	26,884,000
Income/(loss) before disposition of properties	517,000	(3,368,000)
Gains on disposition of properties	1,949,000	24,000
Net income/(loss)	2,466,000	(3,344,000)
Our share of:
Depreciation and amortization of real estate assets	1,031,000	2,015,000
Impairments of real estate assets	0	1,020,000
Interest expense	776,000	1,752,000
Gains on disposition of properties	955,000	421,000
Net income	1,155,000	4,000
Our share of net income	1,155,000	4,000
Adjustments for management and other fees	169,000	432,000
Impairment of investment in unconsolidated affiliate	(1,353,000)	0
Equity in earnings/(losses) of unconsolidated affiliates	(29,000)	436,000
Percentage of equity interest in joint ventures, maximum (in hundredths)	50.00%
Gains on disposition of properties	1,949,000	24,000
Expected aggregate net distributions	230,000	363,000
Board of Trade Investment Company [Member]
Expenses:
Gains on disposition of properties	1,900,000
Our share of:
Proceeds received from disposition of property	8,300,000
Gains on disposition of properties	1,900,000
Expected aggregate net distributions	4,700,000
Net impairment charge on our investment in unconsolidated affiliate	$ 400,000