CONDENSED CONSOLIDATED STATEMENTS OF INCOME AND COMPREHENSIVE INCOME (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011
Revenues:
Rental income	$ 116,281	$ 102,969	$ 336,772	$ 301,839
Residents fees and services	42,352	10,731	113,906	11,575
Total revenues	158,633	113,700	450,678	313,414
Expenses:
Depreciation	35,880	28,824	104,487	82,120
Property operating expenses	47,807	20,153	127,875	41,888
General and administrative	8,352	6,564	24,106	19,513
Acquisition related costs	4,297	2,620	6,814	6,547
Impairment of assets		1,028	3,071	1,194
Total expenses	96,336	59,189	266,353	151,262
Operating income	62,297	54,511	184,325	162,152
Interest and other income	248	394	957	870
Interest expense	(30,417)	(24,730)	(87,426)	(70,837)
Loss on early extinguishment of debt	(6,349)		(6,349)	(427)
Loss on lease terminations	(104)		(104)
(Loss) gain on sale of properties	(101)		(101)	21,315
Equity in earnings of an investee	115	28	236	111
Income before income tax expense	25,689	30,203	91,538	113,184
Income tax expense	(43)	(207)	(290)	(365)
Net income	25,646	29,996	91,248	112,819
Other comprehensive income:
Change in net unrealized gain / loss on investments	7,499	(15,735)	8,416	(18,919)
Share of comprehensive income of an investee	35	15	31	58
Comprehensive income	$ 33,180	$ 14,276	$ 99,695	$ 93,958
Weighted average shares outstanding (in shares)	174,690	153,385	166,698	145,745
Net income per share (in dollars per share)	$ 0.15	$ 0.20	$ 0.55	$ 0.77