LOANS PAYABLE AND SECURED LINE OF CREDIT (Details Textual)		1 Months Ended			12 Months Ended
	May 11, 2016 USD ($)	May 25, 2018	Dec. 22, 2017 USD ($) ft²	Feb. 22, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Sep. 30, 2019 USD ($)	May 24, 2018 USD ($)	Sep. 30, 2017 USD ($)	Aug. 04, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Feb. 09, 2015 USD ($)
Interest Costs Capitalized					$ 152,000
Long-term Line of Credit					0	$ 0
Line of Credit Facility, Expiration Date				Feb. 22, 2019
Loans Payable					123,333,000	36,167,000
Debt Instrument, Interest Rate Terms		bearing interest at a blended average rate of 3.72% over the 30-day LIBOR, each with a one year extension option upon satisfaction of certain conditions.
Debt Instrument, Payment Terms		a guaranty of 25% of the principal amount, decreasing to 10% of the principal balance upon the debt yield ratio becoming equal to or greater than 7.0%.
Cash and Cash Equivalents, at Carrying Value					$ 11,496,000	15,273,000					$ 4,678,000	$ 38,173,000
Maximum [Member]
Debt Instrument, Interest Rate, Stated Percentage	3.00%		2.50%
Loans Payable [Member]
Debt Instrument, Interest Rate, Effective Percentage					6.22%
Debt Instrument, Face Amount								$ 67,800,000
Landmarked Robert And Anne Dickey House [Member]
Area of Real Estate Property | ft²			7,500
Sterling National Bank [Member]
Debt Instrument, Description of Variable Rate Basis				100	200
Line of Credit Facility, Maximum Borrowing Capacity				$ 12,000,000	$ 12,750,000	11,000,000			$ 11,000,000
Secured Debt										$ 2,900,000
Line of Credit Facility, Remaining Borrowing Capacity									$ 9,100,000
Interest Rate Cap [Member]
Interest Expense, Debt					3,000	3,000
Interest Rate Cap [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivative Asset, Fair Value, Gross Asset					$ 497,000	$ 344,000
West Palm Beach Florida Loan [Member]
Debt Instrument, Interest Rate, Basis for Effective Rate	interest at 30-day LIBOR plus 230 basis points.
Debt Instrument, Interest Rate, Effective Percentage					4.80%	3.86%
Debt Instrument, Unamortized Premium	$ 14,000
Line of Credit Facility, Maximum Borrowing Capacity	12,600,000
Derivative, Notional Amount	9,100,000
Line of Credit Facility, Remaining Borrowing Capacity					$ 3,500,000
West Palm Beach Florida Loan [Member] | Interest Rate Cap [Member] | Prepaid Expenses and Other Current Assets [Member]
Derivative Asset, Fair Value, Gross Asset					1,000	$ 5,000
Greenwich Loan [Member]
Debt Instrument, Interest Rate, Effective Percentage													5.50%
Line of Credit Facility, Maximum Borrowing Capacity													$ 40,000,000
Greenwich Construction Loan [Member]
Debt Instrument, Unamortized Premium			$ 393,000
Derivative, Notional Amount			189,500,000
Debt Instrument, Face Amount			$ 189,500,000
Number of Real Estate Properties			90
Debt Instrument, Description			(i) LIBOR plus 8.25% and (ii) 9.25%. The effective interest rate on the 77 Greenwich Construction Facility was 10.6% as of December 31, 2018 and 9.81% at December 31, 2017.
Loans Payable					$ 51,500,000	$ 32,700,000
Cash and Cash Equivalents, at Carrying Value			$ 15,000,000
Greenwich Construction Loan [Member] | Subsequent Event [Member]
Cash and Cash Equivalents, at Carrying Value							$ 10,000,000
Greenwich Construction Loan [Member] | Multi Use Building [Member]
Area of Real Estate Property | ft²			300,000
TPH Borrower [Member] | West Palm Beach Florida Loan [Member]
Long-term Line of Credit	$ 9,100,000
Canadian Imperial Bank of Commerce [Member] | Loans Payable [Member]
Debt Instrument, Face Amount								52,400,000
Debt, Weighted Average Interest Rate					0.50%
RCG LV Debt VI REIT LLC [Member] | Mezzanine Loan [Member]
Debt Instrument, Face Amount								$ 15,400,000