v2.4.0.6
Segment Information (Details 2) (USD $)
 12 Months Ended
Dec. 31, 2012
Dec. 31, 2011
Dec. 31, 2010
Assets      
Total assets $ 18,980,000,000 $ 17,271,910,000  
Percentage of total assets 100.00% 100.00%  
Capital expenditures      
Total capital expenditures 1,901,916,000 629,669,000 294,296,000
Triple-Net Leased Properties
      
Assets      
Total assets 8,368,186,000 8,704,061,000  
Percentage of total assets 44.10% 50.40%  
Capital expenditures      
Total capital expenditures 139,680,000 133,761,000 12,884,000
Capital expenditures from funds held in Code Section 1031 exchange escrow account     58,100,000
Senior Living Operations
      
Assets      
Total assets 6,274,207,000 5,758,497,000  
Percentage of total assets 33.10% 33.30%  
Capital expenditures      
Total capital expenditures 758,371,000 370,455,000 10,268,000
Capital expenditures from funds held in Code Section 1031 exchange escrow account     64,700,000
MOB Operations
      
Assets      
Total assets 3,703,453,000 2,433,160,000  
Percentage of total assets 19.50% 14.10%  
Capital expenditures      
Total capital expenditures 1,003,865,000 125,453,000 271,144,000
Capital expenditures from funds held in Code Section 1031 exchange escrow account     11,200,000
All Other
      
Assets      
Total assets $ 634,154,000 $ 376,192,000  
Percentage of total assets 3.30% 2.20%