Related Party Transactions and Arrangements - Related Party Loans Payable (Details) - Affiliated Entity - Mortgage loans payable
$ in Thousands
3 Months Ended 9 Months Ended
Sep. 30, 2019
USD ($)
Property
loan
Sep. 30, 2018
USD ($)
Sep. 30, 2019
USD ($)
Property
loan
Sep. 30, 2018
USD ($)
Dec. 31, 2018
USD ($)
Related Party Transaction [Line Items]          
Interest expense on note payable $ 58 $ 72 $ 200 $ 96  
Related party notes payable          
Related Party Transaction [Line Items]          
Number of mortgage loans with related party | loan 4   4    
Number of properties with related party | Property 6   6    
Outstanding principal of related parties notes payable         $ 27,900