Acquisitions of Real Estate Property (Details) (USD $) In Thousands	Sep. 30, 2011
Atria Senior Living Acquisition [Member]
Fair values of the assets acquired and liabilities assumed at the date of acquisition
Land and improvements	$ 342,330
Buildings and improvements	2,878,807
Acquired lease intangibles	160,340
Other assets	213,325
Total assets acquired	3,594,802
Notes payable and other debt	1,629,212
Deferred tax liability	43,889
Other liabilities	203,082
Total liabilities assumed	1,876,183
Net assets acquired	1,718,619
Cash acquired	77,718
Equity issued	1,376,437
Total cash used	264,464
Nationwide Health Properties [Member]
Fair values of the assets acquired and liabilities assumed at the date of acquisition
Land and improvements	687,142
Buildings and improvements	6,414,258
Acquired lease intangibles	515,535
Other assets	701,743
Total assets acquired	8,318,678
Notes payable and other debt	1,879,014
Other liabilities	789,040
Total liabilities assumed	2,668,054
Redeemable OP unitholder interests assumed	100,429
Noncontrolling interest assumed	83,702
Net assets acquired	5,466,493
Cash acquired	29,202
Equity issued	5,361,493
Total cash used	$ 75,798