Segment Reporting (Details) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010 Activity Property	Dec. 31, 2010
Summary of information for reportable segments
Rental Income	$ 250,081	$ 154,729	$ 666,332	$ 450,629
Resident fees and services	125,125	12,809	319,559	12,809
Interest income	7,858	10,054	32,433	28,437
Other income	1,809	1,156	9,974	4,802
Total Revenues	384,873	178,748	1,028,298	496,677
Property Operating Expenses	104,067	21,822	270,408	48,545
Net Operating Income	280,806	156,926	757,890	448,132
Real Estate Depreciation/Amortization	115,640	52,393	301,461	143,424
Interest Expense	87,811	44,985	231,914	112,520
Total assets	13,861,089		13,861,089		9,451,734	[1]
Segment Reporting (Textual) [Abstract]
Number of activity related to the segment				0
Seniors housing triple-net [Member]
Summary of information for reportable segments
Rental Income	169,668	97,658	444,656	288,148
Interest income	6,810	9,179	27,224	26,583
Other income	454	698	5,458	2,726
Total Revenues	176,932	107,535	477,338	317,457
Net Operating Income	176,932	107,535	477,338	317,457
Real Estate Depreciation/Amortization	48,690	27,495	127,088	82,448
Interest Expense	4,110	4,271	9,812	13,964
Total assets	7,696,298		7,696,298
Seniors housing operating [Member]
Summary of information for reportable segments
Resident fees and services	125,125	12,809	319,559	12,809
Total Revenues	125,125	12,809	319,559	12,809
Property Operating Expenses	86,218	7,993	219,824	7,993
Net Operating Income	38,907	4,816	99,735	4,816
Real Estate Depreciation/Amortization	39,019	4,879	97,326	4,879
Interest Expense	13,945	3,236	33,446	3,236
Total assets	2,240,665		2,240,665
Medical facilities [Member]
Summary of information for reportable segments
Rental Income	80,413	57,071	221,676	162,481
Interest income	1,048	875	5,209	1,854
Other income	1,048	227	3,879	800
Total Revenues	82,509	58,173	230,764	165,135
Property Operating Expenses	17,849	13,829	50,584	40,552
Net Operating Income	64,660	44,344	180,180	124,583
Real Estate Depreciation/Amortization	27,931	20,019	77,047	56,097
Interest Expense	8,356	6,506	23,321	18,560
Total assets	3,657,811		3,657,811
Non-segment/Corporate [Member]
Summary of information for reportable segments
Other income	307	231	637	1,276
Total Revenues	307	231	637	1,276
Net Operating Income	307	231	637	1,276
Interest Expense	61,400	30,972	165,335	76,760
Total assets	$ 266,315		$ 266,315

[1] NOTE: The consolidated balance sheet at December 31, 2010 has been derived from the audited financial statements at that date but does not include all of the information and footnotes required by U.S. generally accepted accounting principles for complete financial statements.