Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012 item	Sep. 30, 2011	Dec. 31, 2011
Segment Reporting
Number of operating segments			3
Number of reportable segments			2
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 (loss)	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
Total assets	4,646,295		4,646,295		4,383,048
Short and Long Term Residential Care Communities
Revenues:
Rental income	60,496	58,391	178,964	172,686
Residents fees and services	42,352	10,731	113,906	11,575
Total revenues	102,848	69,122	292,870	184,261
Expenses:
Depreciation	22,470	18,369	64,432	52,112
Property operating expenses	31,233	8,603	82,976	9,212
Impairment of assets		1,028		1,028
Total expenses	53,703	28,000	147,408	62,352
Operating income (loss)	49,145	41,122	145,462	121,909
Interest expense	(11,594)	(11,152)	(37,748)	(31,751)
Loss on lease terminations	(104)		(104)
(Loss) gain on sale of properties				21,236
Income before income tax expense	37,447	29,970	107,610	111,394
Net income	37,447	29,970	107,610	111,394
Total assets	2,604,149	2,079,432	2,604,149	2,079,432
MOBs
Revenues:
Rental income	51,346	40,139	144,491	115,887
Total revenues	51,346	40,139	144,491	115,887
Expenses:
Depreciation	12,462	9,507	37,211	27,164
Property operating expenses	16,574	11,550	44,899	32,676
Impairment of assets			3,071	166
Total expenses	29,036	21,057	85,181	60,006
Operating income (loss)	22,310	19,082	59,310	55,881
Interest expense	(1,014)	(254)	(1,807)	(686)
(Loss) gain on sale of properties	(101)		(101)	79
Income before income tax expense	21,195	18,828	57,402	55,274
Net income	21,195	18,828	57,402	55,274
Total assets	1,625,180	1,465,833	1,625,180	1,465,833
All Other Operations
Revenues:
Rental income	4,439	4,439	13,317	13,266
Total revenues	4,439	4,439	13,317	13,266
Expenses:
Depreciation	948	948	2,844	2,844
General and administrative	8,352	6,564	24,106	19,513
Acquisition related costs	4,297	2,620	6,814	6,547
Total expenses	13,597	10,132	33,764	28,904
Operating income (loss)	(9,158)	(5,693)	(20,447)	(15,638)
Interest and other income	248	394	957	870
Interest expense	(17,809)	(13,324)	(47,871)	(38,400)
Loss on early extinguishment of debt	(6,349)		(6,349)	(427)
Equity in earnings of an investee	115	28	236	111
Income before income tax expense	(32,953)	(18,595)	(73,474)	(53,484)
Income tax expense	(43)	(207)	(290)	(365)
Net income	(32,996)	(18,802)	(73,764)	(53,849)
Total assets	416,966	458,048	416,966	458,048
Consolidated
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 (loss)	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
Total assets	$ 4,646,295	$ 4,003,313	$ 4,646,295	$ 4,003,313