FAIR VALUE MEASUREMENTS - Fair Value of Debt Obligations (Details) $ in Thousands	Sep. 30, 2020 USD ($)	Dec. 31, 2019 USD ($)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Line of credit, fair value	$ 77,600	$ 81,600
Mortgage loans payable	126,710	126,601
Note to affiliate	4,100	4,500
Mortgages
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Mortgage loans payable	$ 126,710	$ 126,601
Minimum | Line of Credit | Discounted cash flow | Loan to value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.518	0.546
Minimum | Line of Credit | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0185	0.0334
Minimum | Mortgages | Discounted cash flow | Loan to value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.369	0.391
Minimum | Mortgages | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0275	0.0355
Minimum | Note to Affiliate | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0475	0.0500
Maximum | Line of Credit | Discounted cash flow | Loan to value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.518	0.546
Maximum | Line of Credit | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0185	0.0334
Maximum | Mortgages | Discounted cash flow | Loan to value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.601	0.593
Maximum | Mortgages | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0500	0.0420
Maximum | Note to Affiliate | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0475	0.0500
Weighted Average | Line of Credit | Discounted cash flow | Loan to value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.518	0.546
Weighted Average | Line of Credit | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0185	0.0334
Weighted Average | Mortgages | Discounted cash flow | Loan to value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.503	0.513
Weighted Average | Mortgages | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0375	0.0381
Weighted Average | Note to Affiliate | Discounted cash flow | Market interest rate
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Fair value input	0.0475	0.0500