ACQUISITIONS OF REAL ESTATE PROPERTY (Details 4) (USD $)			1 Months Ended		1 Months Ended
	Mar. 31, 2012	Dec. 31, 2011	Apr. 30, 2012 Cogdell Acquisition property	Apr. 02, 2012 Cogdell Acquisition	Apr. 30, 2012 Sunrise Acquisition property
Pending Acquisition
Number of MOBs in which ownership interest acquired			72
Number of MOBs managed by property management business of acquiree			44
Purchase price of acquired asset				$ 760,000,000	$ 362,000,000
Number of MOBs which is still being developed			1
Joint venture partners' share of total debt	64,400,000	46,600,000		36,600,000
Right to receive cash per share on each outstanding share of common stock outstanding (in dollars per share)			$ 4.25
Right to receive cash per share on each outstanding unit of limited partnership interest outstanding (in dollars per share)			$ 4.25
Preferred stock, Dividend rate			8.50%
Right to receive cash per share on each outstanding share 8.500% Series A Cumulative Redeemable Perpetual Preferred Stock (in dollars per share)			$ 25.00
Mortgage Debt assumed				$ 203,800,000
Senior housing communities intended to acquire					16