Real Estate Investments - Discontinued Operations and Assets Held for Sale - Income Statement (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2014	Jun. 30, 2013	Jun. 30, 2014	Jun. 30, 2013
Revenues
Rental income	$ 90,541	$ 76,883	$ 178,301	$ 152,687
Revenues	92,935	81,818	184,765	162,015
Expenses
Property operating	34,136	31,235	67,510	60,636
General and administrative	5,666	5,840	11,644	12,380
Depreciation	24,911	21,379	48,990	42,501
Amortization	2,775	2,559	5,534	5,225
Bad debt, net of recoveries	73	19	120	7
Total Expenses	67,561	61,032	133,798	120,749
Other Income (Expense)
Loss on extinguishment of debt	0	(29,638)		(29,638)
Interest expense	(18,066)	(18,925)	(35,984)	(38,695)
Interest and other income, net	2,036	219	2,136	449
Total other income (expense)	(16,030)	(48,344)	(33,848)	(67,884)
Discontinued Operations
Income from discontinued operations	(231)	1,537	(619)	3,209
Impairments	(3,105)	0	(6,529)	(3,630)
Gain on sales of real estate properties	3	1,783	3	1,783
INCOME (LOSS) FROM DISCONTINUED OPERATIONS	(3,333)	3,320	(7,145)	1,362
Discontinued Operations [Member]
Revenues
Rental income	123	3,170	449	6,409
Revenues	123	3,170	449	6,409
Expenses
Property operating	292	616	862	1,357
General and administrative	1	1	2	3
Depreciation	56	716	198	1,493
Amortization	0	20	0	43
Bad debt, net of recoveries	7	0	8	0
Total Expenses	356	1,353	1,070	2,896
Other Income (Expense)
Loss on extinguishment of debt	0	(270)	0	(270)
Interest expense	0	(16)	0	(41)
Interest and other income, net	2	6	2	7
Total other income (expense)	2	(280)	2	(304)
Discontinued Operations
Income from discontinued operations	(231)	1,537	(619)	3,209
Impairments	(3,105)	0	(6,529)	(3,630)
Gain on sales of real estate properties	3	1,783	3	1,783
INCOME (LOSS) FROM DISCONTINUED OPERATIONS	$ (3,333)	$ 3,320	$ (7,145)	$ 1,362