CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012
Revenues:
Rental income	$ 114,373	$ 109,505
Residents fees and services	75,056	35,568
Total revenues	189,429	145,073
Expenses:
Property operating expenses	74,582	39,334
Depreciation	38,302	33,377
General and administrative	8,648	7,685
Acquisition related costs	1,903	688
Impairment of assets	1,304	3,071
Total expenses	124,739	84,155
Operating income	64,690	60,918
Interest and other income	173	482
Interest expense	(29,564)	(28,889)
Equity in earnings of an investee	76	45
Income before income tax expense	35,375	32,556
Income tax expense	(140)	(204)
Net income	35,235	32,352
Other comprehensive income:
Change in net unrealized gain / loss on investments	8,764	2,231
Share of comprehensive income of an investee	(8)	(1)
Comprehensive income	$ 43,991	$ 34,582
Weighted average shares outstanding (in shares)	184,605	162,647
Net income per share (in dollars per share)	$ 0.19	$ 0.20