Acquisitions and Dispositions of Real Estate Property - Estimated Fair Value (Details) - USD ($)
$ in Thousands
12 Months Ended
Dec. 31, 2015
Dec. 31, 2014
Dec. 31, 2013
Business Acquisition [Line Items]      
Goodwill $ 145,374 $ 88,959 $ 88,989
Business Acquisitions, 2015      
Business Acquisition [Line Items]      
Land and improvements 38,361    
Buildings and improvements 515,620    
Acquired lease intangibles 14,138    
Goodwill 56,275    
Other assets 8,034    
Total assets acquired 632,428    
Tenant deposits 8,801    
Lease intangible liabilities 3,729    
Accounts payable and other liabilities 1,343    
Total liabilities assumed 13,873    
Net assets acquired 618,555    
American Realty Capital Healthcare Trust      
Business Acquisition [Line Items]      
Goodwill, Period Increase (Decrease) $ (1,800)