Condensed Consolidated Statements of Operations and Comprehensive Loss (USD $) In Thousands, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014
Income Statement [Abstract]
Rental revenue	$ 74,047	$ 68,298
Expenses
Property operating expenses	24,244	24,709
Interest expense	15,787	15,847
Real estate taxes	11,419	9,758
Property management fees	2,271	2,063
Asset impairment losses	132	0
General and administrative	6,414	4,695
Depreciation and amortization	30,022	28,161
Total expenses	90,289	85,233
Interest and other income	146	249
Loss on early extinguishment of debt	(36)	0
Loss from continuing operations before income taxes and equity in operations of investments	(16,132)	(16,686)
Benefit (provision) for income taxes	76	(68)
Equity in operations of investments	243	88
Loss from continuing operations	(15,813)	(16,666)
Discontinued operations
Income (loss) from discontinued operations	1,305	(12,991)
Gain on sale of discontinued operations	8,606	0
Income (loss) from discontinued operations	9,911	(12,991)
Net loss	(5,902)	(29,657)
Net loss attributable to noncontrolling interests
Noncontrolling interests in continuing operations	27	24
Noncontrolling interests in discontinued operations	(17)	19
Net loss attributable to common stockholders	(5,892)	(29,614)
Basic and diluted weighted average common shares outstanding (in shares)	299,348,615	299,228,783
Basic and diluted income (loss) per common share:
Continuing operations (in dollars per share)	$ (0.05)	$ (0.06)
Discontinued operations (in dollars per share)	$ 0.03	$ (0.04)
Basic and diluted loss per common share (in dollars per share)	$ (0.02)	$ (0.10)
Net income (loss) attributable to common stockholders:
Continuing operations	(15,786)	(16,642)
Discontinued operations	9,894	(12,972)
Net loss attributable to common stockholders	(5,892)	(29,614)
Comprehensive loss:
Net loss	(5,902)	(29,657)
Other comprehensive loss: unrealized gain on interest rate derivatives	(4,556)	0
Comprehensive loss	(10,458)	(29,657)
Comprehensive loss attributable to noncontrolling interests	18	43
Comprehensive loss attributable to common stockholders	$ (10,440)	$ (29,614)