v3.21.2
Credit Risk Concentrations - Additional Information (Detail) - Customer
3 Months Ended 9 Months Ended 12 Months Ended
Sep. 30, 2021
Sep. 30, 2020
Sep. 30, 2021
Sep. 30, 2020
Dec. 31, 2020
Concentration Risk [Line Items]          
Number of tenants or common franchises 0 0 0 0  
Mortgages and Notes Payable | Credit Availability Concentration Risk | Financial Institution One          
Concentration Risk [Line Items]          
Concentrations risk percentage     68.00%   63.00%
Mortgages and Notes Payable | Credit Availability Concentration Risk | Financial Institution Two          
Concentration Risk [Line Items]          
Concentrations risk percentage     18.00%   16.00%
Mortgages and Notes Payable | Credit Availability Concentration Risk | Financial Institution Three          
Concentration Risk [Line Items]          
Concentrations risk percentage         10.00%