Real Property Acquisitions and Development (Details 2) (USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010
Real property acquisitions:
Properties	244	59
Amount	$ 4,641,088	$ 1,042,354
Less: Assumed debt	(727,882)	(353,165)
Assumed other items, net	(152,391)	(152,349)
Cash disbursed for acquisitions	3,760,815	536,840
Construction in progress additions:
Amount	260,280	247,088
Less: Capitalized interest	(10,090)	(15,536)
Accruals	(33,451)	(8,088)
Cash disbursed for construction in progress	216,739	223,464
Capital improvements to existing properties	52,890	40,660
Total cash invested in real property	4,030,444	800,964
Development projects:
Total development projects	365,024	415,234
Expansion projects	43,793	2,320
Total construction in progress conversions	408,817	417,554
Seniors housing operating [Member]
Real property acquisitions:
Properties	46	25
Amount	1,126,130	576,000
Seniors housing triple-net [Member]
Real property acquisitions:
Properties	179	15
Amount	3,202,273	219,772
Construction in progress additions:
Amount	121,382	62,115
Development projects:
Total development projects	39,462	269,261
Land parcels [Member]
Real property acquisitions:
Properties	1	0
Amount	6,770	0
Medical facilities [Member]
Real property acquisitions:
Properties	18	19
Amount	305,915	246,582
Construction in progress additions:
Amount	138,898	184,973
Development projects:
Total development projects	$ 325,562	$ 145,973