Debt - Debt Extinguishment - Narrative (Details)
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2015
USD ($)
Property
Sep. 30, 2014
USD ($)
Property
Sep. 30, 2015
USD ($)
Property
Sep. 30, 2014
USD ($)
Property
Debt Instrument [Line Items]        
Gain (loss) on debt extinguishment $ 342 $ 212 $ 2,489 $ (64,496)
Number of properties disposed of during period | Property 0 1 2 6
CMBS Loans        
Debt Instrument [Line Items]        
Number of properties disposed of during period | Property     5  
Mortgages        
Debt Instrument [Line Items]        
Amount of debt defeasance     $ 378,600 $ 532,800
Weighted average contractual interest rate 5.64% 6.53% 5.64% 6.53%
Gain (loss) on debt extinguishment     $ 2,500 $ (64,500)
Reduction of debt     17,500  
Proceeds from sale of properties     $ 14,000  
Mortgages | CMBS Loans        
Debt Instrument [Line Items]        
Number of properties disposed of during period | Property     4  
Mortgages | Shopko properties        
Debt Instrument [Line Items]        
Amount of debt defeasance     $ 488,700  
Net-lease Mortgage Notes        
Debt Instrument [Line Items]        
Amount of debt defeasance     $ 18,000