Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended		12 Months Ended
	Sep. 30, 2011 property segment Y count state	Sep. 30, 2010	Sep. 30, 2011 property segment Y count state	Sep. 30, 2010	Dec. 31, 2010
Segment Reporting
Number of reportable segments	2		2
Revenues:
Rental income	$ 102,546	$ 80,961	$ 300,527	$ 242,173
Residents fees and services	10,731		11,575
Total revenues	113,277	80,961	312,102	242,173
Expenses:
Depreciation expense	28,824	22,505	82,120	67,139
Property operating expenses	19,754	4,599	40,572	13,138
General and administrative	6,608	5,545	19,618	16,439
Acquisition related costs	2,620	286	6,547	725
Impairment of assets	1,028		1,194	1,095	5,965
Total expenses	58,834	32,935	150,051	98,536
Operating income (loss)	54,443	48,026	162,051	143,637
Interest and other income	462	203	971	703
Interest expense	(24,730)	(20,226)	(70,837)	(59,155)
Loss on early extinguishment of debt			(427)	(2,433)
Gain on sale of properties		109	21,315	109
Equity in earnings of an investee	28	35	111	(17)
Income before income tax expense	30,203	28,147	113,184	82,844
Income tax expense	(207)	(69)	(365)	(223)
Net income	29,996	28,078	112,819	82,621
Total assets	4,003,313	2,999,712	4,003,313	2,999,712	3,392,656
Short and Long Term Residential Care Communities
Revenues:
Rental income	58,391	56,895	172,686	170,219
Residents fees and services	10,731		11,575
Total revenues	69,122		184,261
Expenses:
Depreciation expense	18,369	16,571	52,112	49,533
Property operating expenses	8,603		9,212
Impairment of assets	1,028		1,028	1,095
Total expenses	28,000	16,571	62,352	50,628
Operating income (loss)	41,122	40,324	121,909	119,591
Interest expense	(11,152)	(10,574)	(31,751)	(31,304)
Gain on sale of properties		109	21,236	109
Income before income tax expense	29,970	29,859	111,394	88,396
Net income	29,970	29,859	111,394	88,396
Total assets	2,079,432	1,933,822	2,079,432	1,933,822
MOBs
Revenues:
Rental income	39,716	19,743	114,575	58,986
Total revenues	39,716		114,575
Expenses:
Depreciation expense	9,507	4,986	27,164	14,762
Property operating expenses	11,151	4,599	31,360	13,138
Impairment of assets			166
Total expenses	20,658	9,585	58,690	27,900
Operating income (loss)	19,058	10,158	55,885	31,086
Interest expense	(254)	(234)	(686)	(636)
Gain on sale of properties			79
Income before income tax expense	18,804	9,924	55,278	30,450
Net income	18,804	9,924	55,278	30,450
Total assets	1,465,833	776,126	1,465,833	776,126
All Other Operations
Revenues:
Rental income	4,439	4,323	13,266	12,968
Total revenues	4,439		13,266
Expenses:
Depreciation expense	948	948	2,844	2,844
General and administrative	6,608	5,545	19,618	16,439
Acquisition related costs	2,620	286	6,547	725
Total expenses	10,176	6,779	29,009	20,008
Operating income (loss)	(5,737)	(2,456)	(15,743)	(7,040)
Interest and other income	462	203	971	703
Interest expense	(13,324)	(9,418)	(38,400)	(27,215)
Loss on early extinguishment of debt			(427)	(2,433)
Equity in earnings of an investee	28	35	111	(17)
Income before income tax expense	(18,571)	(11,636)	(53,488)	(36,002)
Income tax expense	(207)	(69)	(365)	(223)
Net income	(18,778)	(11,705)	(53,853)	(36,225)
Total assets	$ 458,048	$ 289,764	$ 458,048	$ 289,764