Segment Reporting (Details) (USD $) In Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2011	Jun. 30, 2010	Jun. 30, 2011	Jun. 30, 2010	Dec. 31, 2010
Summary of information for reportable segments
Rental Income	$ 244,189	$ 151,794	$ 416,251	$ 295,900
Resident fees and services	123,149	0	194,435	0
Interest income	12,866	9,335	24,575	18,383
Other income	5,341	2,650	8,165	3,646
Total Revenues	385,545	163,779	643,426	317,929
Property Operating Expenses	101,027	13,003	166,341	26,722
Net Operating Income	284,518	150,776	477,085	291,207
Real Estate Depreciation/Amortization	111,053	47,451	185,821	91,032
Interest Expense	84,773	37,550	144,103	67,535
Total assets	13,480,661		13,480,661		9,451,734	[1]
Senior housing triple-net [Member]
Summary of information for reportable segments
Rental Income	169,247	97,254	274,988	190,490
Resident fees and services		0		0
Interest income	11,036	8,830	20,414	17,405
Other income	4,497	1,536	5,004	2,028
Total Revenues	184,780	107,620	300,406	209,923
Net Operating Income	184,780	107,620	300,406	209,923
Real Estate Depreciation/Amortization	47,443	28,553	78,399	54,954
Interest Expense	3,637	5,022	5,703	9,693
Total assets	7,338,125		7,338,125
Senior housing operating [Member]
Summary of information for reportable segments
Resident fees and services	123,149		194,435
Total Revenues	123,149		194,435
Property Operating Expenses	84,334		133,606
Net Operating Income	38,815		60,829
Real Estate Depreciation/Amortization	38,176		58,307
Interest Expense	12,974		19,501
Total assets	2,257,709		2,257,709
Medical facilities [Member]
Summary of information for reportable segments
Rental Income	74,942	54,540	141,263	105,410
Resident fees and services		0		0
Interest income	1,830	505	4,161	978
Other income	466	302	2,251	574
Total Revenues	77,238	55,347	147,675	106,962
Property Operating Expenses	16,693	13,003	32,735	26,722
Net Operating Income	60,545	42,344	114,940	80,240
Real Estate Depreciation/Amortization	25,434	18,898	49,115	36,078
Interest Expense	7,681	6,476	14,967	12,053
Total assets	3,428,309		3,428,309
Non-segment/Corporate [Member]
Summary of information for reportable segments
Resident fees and services				0
Other income	378	812	910	1,044
Total Revenues	378	812	910	1,044
Net Operating Income	378	812	910	1,044
Interest Expense	60,481	26,052	103,932	45,789
Total assets	$ 456,518		$ 456,518

[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.