Segment Reporting - Narratives (Details)
3 Months Ended 12 Months Ended
Dec. 31, 2016
USD ($)
Sep. 30, 2016
USD ($)
Jun. 30, 2016
USD ($)
Mar. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
segment
Dec. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Segment Reporting Information [Line Items]              
Number of reportable segments | segment         2    
Impairment charges         $ 29,706,000 $ 1,023,000 $ 570,000
Gain on change in control of interests         49,922,000 0 0
Loss on extinguishment of debt $ (800,000) $ (16,000,000) $ (5,100,000) $ (2,500,000) (24,376,000) (275,000) (263,000)
Goodwill impairment         0    
Shelborne Property Associates, LLC | Third Party | All Other              
Segment Reporting Information [Line Items]              
Goodwill impairment         22,800,000    
Contract termination income         10,600,000    
Guaranteed loss compensation         10,600,000    
Equity Method Investments | Net Lease              
Segment Reporting Information [Line Items]              
Impairment charges         1,900,000   800,000
Mortgages              
Segment Reporting Information [Line Items]              
Loss on extinguishment of debt           (300,000)  
Mortgages | Self storage              
Segment Reporting Information [Line Items]              
Loss on extinguishment of debt         23,600,000    
Level 3 | Nonrecurring              
Segment Reporting Information [Line Items]              
Impairment charges         $ 31,625,000 $ 1,023,000 $ 1,336,000