Real Estate Investments - Discontinued Operations and Assets Held for Sale - Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012
Revenues
Other operating	$ 1,579	$ 1,519	$ 4,544	$ 4,659
Revenues	84,761	76,937	248,153	227,171
Expenses
Property operating	32,652	29,737	93,911	86,937
General and administrative	5,583	4,729	17,965	14,510
Depreciation	22,080	20,348	65,065	60,626
Amortization	2,607	2,529	7,856	7,555
Bad debt, net of recoveries	111	40	118	149
Total Expenses	63,033	57,383	184,915	169,777
Other Income (Expense)
Loss on extinguishment of debt	0	0	(29,638)	0
Interest expense	(17,043)	(18,881)	(55,738)	(55,741)
Interest and other income, net	256	203	705	618
Total other income (expense)	(16,787)	(18,678)	(84,671)	(55,123)
Discontinued Operations
Income from discontinued operations	914	1,554	3,879	7,127
Impairments	(6,259)	(2,860)	(9,889)	(7,197)
Gain on sales of real estate properties	20,187	6,265	21,970	9,696
INCOME (LOSS) FROM DISCONTINUED OPERATIONS	14,842	4,959	15,960	9,626
Discontinued Operations [Member]
Revenues
Rental income	1,513	3,364	6,544	13,354
Other operating	0	4	0	19
Revenues	1,513	3,368	6,544	13,373
Expenses
Property operating	317	804	1,052	2,754
General and administrative	0	3	1	9
Depreciation	285	961	1,294	3,503
Amortization	0	26	18	77
Bad debt, net of recoveries	1	(1)	1	(2)
Total Expenses	603	1,793	2,366	6,341
Other Income (Expense)
Loss on extinguishment of debt	0	0	(270)	0
Interest expense	0	(24)	(40)	(73)
Interest and other income, net	4	3	11	168
Total other income (expense)	4	(21)	(299)	95
Discontinued Operations
Income from discontinued operations	914	1,554	3,879	7,127
Impairments	(6,259)	(2,860)	(9,889)	(7,197)
Gain on sales of real estate properties	20,187	6,265	21,970	9,696
INCOME (LOSS) FROM DISCONTINUED OPERATIONS	$ 14,842	$ 4,959	$ 15,960	$ 9,626