Debt - CMBS - Narrative (Details)
$ in Thousands
3 Months Ended 6 Months Ended
Jun. 30, 2015
USD ($)
Property
loan
Jun. 30, 2014
Property
Jun. 30, 2015
USD ($)
Property
Loan
loan
Jun. 30, 2014
USD ($)
Property
Dec. 31, 2014
USD ($)
Debt Instrument [Line Items]          
Number of properties securing borrowings 145   145    
Capitalized interest | $     $ 3,551 $ 0  
Number of properties disposed of during period 2 3 2 5  
CMBS Loans          
Debt Instrument [Line Items]          
Unamortized deferred financing costs | $ $ 5,800   $ 5,800   $ 6,400
Debt default amount | $ 25,400   25,400    
Restricted cash | $ 3,600   $ 3,600    
Capitalized interest | $ $ 400        
Number of properties disposed of during period 5        
Number of properties surrendered 1        
CMBS Loans | CMBS - fixed-rate          
Debt Instrument [Line Items]          
Number of loans secured by mortgage on leased properties and related assets | loan 153   153    
Effective percentage rate minimum     3.90%    
Effective percentage rate maximum     8.39%    
Number of properties securing borrowings 475   475    
Number of CMBS loans in default | Loan     4    
Number of properties securing loans 10   10    
Debt default amount | $ $ 79,000   $ 79,000    
Interest added to principal | $     5,700    
Restricted cash | $ $ 12,100   $ 12,100    
CMBS Loans | CMBS - fixed-rate | Minimum          
Debt Instrument [Line Items]          
Default interest rate 9.67%   9.67%    
CMBS Loans | CMBS - fixed-rate | Maximum          
Debt Instrument [Line Items]          
Default interest rate 10.88%   10.88%    
CMBS Loans | CMBS - variable-rate          
Debt Instrument [Line Items]          
Number of loans secured by mortgage on leased properties and related assets | loan 9   9    
Number of properties securing borrowings 86   86    
Fixed interest rate, interest rate swaps 5.20%   5.20%    
CMBS Loans | CMBS - variable-rate | Minimum          
Debt Instrument [Line Items]          
Stated Rates 3.18%   3.18%    
CMBS Loans | CMBS - variable-rate | Maximum          
Debt Instrument [Line Items]          
Stated Rates 3.59%   3.59%    
Disposed of by sale | CMBS Loans          
Debt Instrument [Line Items]          
Number of properties disposed of during period 4