Debt - Additional Information - Debt Extinguishment (Details)
$ in Thousands
3 Months Ended 12 Months Ended
Dec. 31, 2018
USD ($)
loan
Sep. 30, 2018
USD ($)
Jun. 30, 2018
USD ($)
Mar. 31, 2018
USD ($)
Dec. 31, 2017
USD ($)
Sep. 30, 2017
USD ($)
Jun. 30, 2017
USD ($)
Mar. 31, 2017
USD ($)
Dec. 31, 2018
USD ($)
Property
loan
Dec. 31, 2017
USD ($)
Dec. 31, 2016
USD ($)
Debt Instrument [Line Items]                      
Gain (loss) on debt extinguishment $ 0 $ 0 $ 5,509 $ 21,583 $ (1,190) $ 1,792 $ 7 $ (30) $ 27,092 $ 579 $ 1,605
Mortgages and Notes Payable                      
Debt Instrument [Line Items]                      
Amount of extinguishment of debt                 $ 202,100    
Weighted average interest rate 5.47%               5.47%    
Gain (loss) on debt extinguishment                 $ 26,700 (1,600)  
Mortgages and Notes Payable | Subsidiaries                      
Debt Instrument [Line Items]                      
Amount of extinguishment of debt                   $ 238,500  
Weighted average interest rate         5.46%         5.46%  
CMBS Loans | CMBS                      
Debt Instrument [Line Items]                      
Amount of extinguishment of debt                 $ 56,200    
Number of loans paid off | loan 6               6    
Number properties, underperforming | Property                 6