Debt Obligations, net (Narrative) (Details)
1 Months Ended 6 Months Ended 12 Months Ended
Jul. 31, 2019
USD ($)
loan
Jun. 30, 2017
USD ($)
extension
Jun. 30, 2017
USD ($)
extension
Dec. 31, 2019
USD ($)
Dec. 31, 2018
USD ($)
Line of Credit Facility [Line Items]          
Number of Mortgages Refinanced | loan 2        
Loss on early extinguishment of debt $ 2,000,000.0     $ 2,011,000 $ 0
Consolidated tangible net worth       $ 632,800,000  
2017 Revolver          
Line of Credit Facility [Line Items]          
Maximum leverage ratio       70.00%  
Maximum leverage ratio for 180 day period       75.00%  
Debt instrument covenant multiple of minimum fixed charges on outstanding borrowings       1.40  
Tangible net worth, percent of future issuances of net equity       75.00%  
Maximum secured leverage ratio       70.00%  
Maximum secured leverage ratio for 180 day period       75.00%  
Covenant description secured recourse debt ratio maximum       5.00%  
Future annualized distribution rate of adjusted funds from operations       110.00%  
2017 Revolver | Line of Credit          
Line of Credit Facility [Line Items]          
Maximum borrowing capacity   $ 300,000,000.0 $ 300,000,000.0 $ 525,000,000.0  
Accordion feature, increase limit   $ 1,000,000,000.0 $ 1,000,000,000.0    
Number of extension options available | extension   2 2    
Debt extension term     12 months    
Maximum leverage rate       67.00%  
Remaining borrowing capacity       $ 359,000,000.0  
Additional unsecured borrowing capacity       $ 118,200,000  
2017 Revolver | Line of Credit | LIBOR          
Line of Credit Facility [Line Items]          
Basis point spread on variable interest rate (as a percent)   1.30%      
Minimum | 2017 Revolver | Line of Credit          
Line of Credit Facility [Line Items]          
Unused capacity, commitment fee percentage       0.15%  
Maximum | 2017 Revolver | Line of Credit          
Line of Credit Facility [Line Items]          
Unused capacity, commitment fee percentage       0.25%