Debt - CMBS - Narrative (Details)
$ in Thousands
3 Months Ended
Mar. 31, 2017
USD ($)
Property
Loan
loan
Mar. 31, 2016
USD ($)
Dec. 31, 2016
USD ($)
Debt Instrument [Line Items]      
Weighted average stated interest rate, excluding defaulted loans (as a percent) 5.34%    
Unamortized deferred financing costs $ 35,086   $ 37,111
Capitalized interest $ 714 $ 1,260  
Weighted Average      
Debt Instrument [Line Items]      
Stated interest rate (as a percent) 4.31%    
CMBS fixed-rate | Weighted Average      
Debt Instrument [Line Items]      
Stated interest rate (as a percent) 5.60%    
CMBS Loans      
Debt Instrument [Line Items]      
Unamortized deferred financing costs $ 4,500   $ 4,700
CMBS Loans | CMBS fixed-rate      
Debt Instrument [Line Items]      
Number of loans secured by mortgage on leased properties and related assets | loan 19    
Number of properties securing borrowings | Property 123    
Number of properties securing loans | Property 4    
Debt default amount $ 27,200    
Capitalized interest $ 10,100    
CMBS Loans | CMBS fixed-rate | Minimum      
Debt Instrument [Line Items]      
Stated interest rate (as a percent) 3.90%    
Default interest rate (as a percent) 9.85%    
CMBS Loans | CMBS fixed-rate | Maximum      
Debt Instrument [Line Items]      
Stated interest rate (as a percent) 6.522%    
Default interest rate (as a percent) 10.62%    
Discontinued Operations, Disposed of by Sale | CMBS Loans      
Debt Instrument [Line Items]      
Number of loans in default | Loan 2