Consolidated Statements of Operations (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended									12 Months Ended
	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Mar. 31, 2010	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
REVENUES
Rental income										$ 301,055	$ 276,712	$ 239,037
Mortgage interest										9,186	6,973	2,377
Other operating										6,109	7,907	8,583
Total Revenue	81,260	79,528	78,551	77,011	75,259	74,259	71,358	70,716		316,350	291,592	249,997
EXPENSES
Property operating										117,683	113,083	98,101
General and administrative				400				200	200	20,908	20,990	16,886
Impairment												1,259
Depreciation										85,122	75,292	64,016
Amortization										10,510	8,198	5,314
Bad debt, net of recoveries										243	(250)	(427)
Total Expenses										234,466	217,313	185,149
OTHER INCOME (EXPENSE)
Loss on extinguishment of debt											(1,986)	(480)
Interest expense										(75,053)	(76,038)	(65,710)
Interest and other income, net										981	819	2,402
Total other income (expense)										(74,072)	(77,205)	(63,788)
INCOME (LOSS) FROM CONTINUING OPERATIONS	395	2,507	2,826	2,084	1,739	46	1,489	(6,200)		7,812	(2,926)	1,060
DISCONTINUED OPERATIONS
Income from discontinued operations										1,757	2,404	5,087
Impairments										(14,908)	(6,697)	(6,252)
Gain on sales of real estate properties										10,874	7,035	8,352
INCOME (LOSS) FROM DISCONTINUED OPERATIONS	(6,757)	3,328	102	1,050	1,178	604	522	438		(2,277)	2,742	7,187
NET INCOME (LOSS)	(6,362)	5,835	2,928	3,134	2,917	650	2,011	(5,762)		5,535	(184)	8,247
Less: Net income attributable to noncontrolling interests	(30)	(20)	(20)	0	0	(3)	0	(27)		(70)	(30)	(47)
NET INCOME (LOSS) ATTRIBUTABLE TO COMMON STOCKHOLDERS	$ (6,392)	$ 5,815	$ 2,908	$ 3,134	$ 2,917	$ 647	$ 2,011	$ (5,789)		$ 5,465	$ (214)	$ 8,200
BASIC EARNINGS (LOSS) PER COMMON SHARE:
Income (loss) from continuing operations (in dollars per share)	$ 0.00	$ 0.04	$ 0.04	$ 0.03	$ 0.02	$ 0.00	$ 0.02	$ (0.10)		$ 0.10	$ (0.04)	$ 0.02
Discontinued operations (in dollars per share)	$ (0.07)	$ 0.04	$ 0.00	$ 0.01	$ 0.02	$ 0.01	$ 0.01	$ 0.01		$ (0.03)	$ 0.04	$ 0.11
Net income (loss) attributable to common stockholders (in dollars per share)	$ (0.07)	$ 0.08	$ 0.04	$ 0.04	$ 0.04	$ 0.01	$ 0.03	$ (0.09)		$ 0.07		$ 0.13
DILUTED EARNINGS (LOSS) PER COMMON SHARE:
Income (loss) from continuing operations (in dollars per share)	$ 0.00	$ 0.03	$ 0.04	$ 0.03	$ 0.02	$ 0.00	$ 0.02	$ (0.10)		$ 0.10	$ (0.04)	$ 0.02
Discontinued operations	$ (0.07)	$ 0.04	$ 0.00	$ 0.01	$ 0.02	$ 0.01	$ 0.01	$ 0.01		$ (0.03)	$ 0.04	$ 0.11
Net income (loss) attributable to common stockholders (in dollars per share)	$ (0.07)	$ 0.07	$ 0.04	$ 0.04	$ 0.04	$ 0.01	$ 0.03	$ (0.09)		$ 0.07		$ 0.13
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING - BASIC (in shares)										78,844,840	72,720,147	61,722,786
WEIGHTED AVERAGE COMMON SHARES OUTSTANDING - DILUTED (in shares)										80,127,883	72,720,147	62,770,826