Debt - CMBS - Narrative (Details)
$ in Thousands
6 Months Ended
Jun. 30, 2017
USD ($)
Property
loan
Loan
Jun. 30, 2016
USD ($)
Dec. 31, 2016
USD ($)
Debt Instrument [Line Items]      
Weighted average stated interest rate, excluding defaulted loans 5.32%    
Unamortized deferred financing costs $ 33,132   $ 37,111
Capitalized interest 1,206 $ 2,175  
CMBS Loans      
Debt Instrument [Line Items]      
Unamortized deferred financing costs $ 4,400   $ 4,700
CMBS Loans | CMBS fixed-rate      
Debt Instrument [Line Items]      
Number of loans secured by mortgage on leased properties and related assets | loan 17    
Number of properties securing borrowings | Property 120    
Number of properties securing loans | Property 6    
Debt default amount $ 53,600    
Capitalized interest $ 10,700    
CMBS Loans | CMBS fixed-rate | Minimum      
Debt Instrument [Line Items]      
Stated interest rate 3.90%    
Default interest rate 7.53%    
CMBS Loans | CMBS fixed-rate | Maximum      
Debt Instrument [Line Items]      
Stated interest rate 6.522%    
Default interest rate 10.62%    
Discontinued Operations, Disposed of by Sale | CMBS Loans      
Debt Instrument [Line Items]      
Number of loans in default | Loan 4