Segment Disclosures (Details 3) (USD $)	Jun. 30, 2012	Dec. 31, 2011	Oct. 05, 2006 CRC	Jun. 30, 2012 Identifiable segment	Dec. 31, 2011 Identifiable segment	Jun. 30, 2012 Senior housing	Dec. 31, 2011 Senior housing	Jun. 30, 2012 Post-acute/skilled nursing	Dec. 31, 2011 Post-acute/skilled nursing	Jun. 30, 2012 Life science	Dec. 31, 2011 Life science	Jun. 30, 2012 Medical office	Dec. 31, 2011 Medical office	Jun. 30, 2012 Hospital	Dec. 31, 2011 Hospital	Jun. 30, 2012 Other non-segment	Dec. 31, 2011 Other non-segment
Reconciliation of assets from segment to consolidated
Gross segment assets				$ 18,905,716,000	$ 18,536,595,000	$ 5,956,879,000	$ 5,911,352,000	$ 5,923,120,000	$ 5,644,472,000	$ 3,915,856,000	$ 3,886,851,000	$ 2,353,948,000	$ 2,336,302,000	$ 755,913,000	$ 757,618,000
Accumulated depreciation and amortization				(1,825,257,000)	(1,670,511,000)
Total assets	17,789,768,000	17,408,475,000		17,080,459,000	16,866,084,000											709,309,000	538,232,000
Real estate held for sale, net		4,159,000															4,159,000
Amount paid in merger in excess of the fair value, recorded as goodwill			51,700,000
Goodwill	$ 50,346,000	$ 50,346,000		$ 50,346,000		$ 31,000,000		$ 3,000,000				$ 11,000,000		$ 5,000,000