LONG-TERM DEBT - Outstanding Indebtedness (Details) - USD ($)
$ in Thousands
9 Months Ended
Sep. 30, 2021
May 21, 2021
Apr. 30, 2020
Long-term debt      
Total Debt $ 191,500    
Margin added to variable rate basis (as a percent) 2.30%    
Credit Facility      
Long-term debt      
Total Debt $ 21,500    
Credit Facility | LIBOR | Minimum      
Long-term debt      
Margin added to variable rate basis (as a percent) 1.35%    
Credit Facility | LIBOR | Maximum      
Long-term debt      
Margin added to variable rate basis (as a percent) 1.95%    
2026 Term Loan      
Long-term debt      
Total Debt $ 60,000 $ 60,000  
2026 Term Loan | LIBOR      
Long-term debt      
Stated Interest Rate (as a percent)   0.81%  
2026 Term Loan | LIBOR | Minimum      
Long-term debt      
Margin added to variable rate basis (as a percent) 1.35%    
2026 Term Loan | LIBOR | Maximum      
Long-term debt      
Margin added to variable rate basis (as a percent) 1.95%    
2027 Term Loan      
Long-term debt      
Total Debt $ 80,000    
2027 Term Loan | Interest Rate Swap      
Long-term debt      
Notional amount     $ 50,000
2027 Term Loan | LIBOR      
Long-term debt      
Stated Interest Rate (as a percent) 0.53%    
2027 Term Loan | LIBOR | Minimum      
Long-term debt      
Margin added to variable rate basis (as a percent) 1.25%    
2027 Term Loan | LIBOR | Maximum      
Long-term debt      
Margin added to variable rate basis (as a percent) 1.90%    
Mortgage Note Payable - CMBS Portfolio      
Long-term debt      
Total Debt $ 30,000    
Margin added to variable rate basis (as a percent) 4.33%