Stockholder's Equity (Details Textuals) (USD $)	1 Months Ended				1 Months Ended		6 Months Ended
	Feb. 28, 2011	Jun. 30, 2011	May 31, 2011	Dec. 31, 2010	May 31, 2011 Atria Acquisition [Member]	May 12, 2011 Atria Acquisition [Member]	Jun. 30, 2011 Nationwide Health Properties [Member]
Business Acquisition [Line Items]
Common stock shares issued related to acquisition					24,958,543		99,849,106
Shares reserved for issuance in connection with equity awards and other convertible or exchangeable securities							2,253,366
Common stock, shares issued, value			$ 1,380,000,000			$ 1,380,000,000
Accrued dividend							23,800,000
Prorated dividend on common stock		$ 0.1264
Common stock shares issued related to acquisition per share					$ 55.33
Stockholders' Equity (Textuals) [Abstract]
Shares of common stock issued and sold in an underwritten public offering	5,563,000
Aggregate proceeds from the sale of common stock in an underwritten public offering pursuant	$ 300,000,000
Capital stock authorized		610,000,000
Common stock, shares authorized		300,000,000		300,000,000
Common stock, par value		$ 0.25		$ 0.25
Preferred stock, shares authorized		10,000,000		10,000,000
Preferred stock, par value		$ 1.00		$ 1.00