LOANS PAYABLE AND SECURED LINE OF CREDIT - Additional Information (Details)		1 Months Ended						6 Months Ended	9 Months Ended	12 Months Ended
	Jan. 15, 2020 USD ($) $ / shares	Oct. 31, 2021 USD ($) item	Jun. 30, 2021 USD ($) item	Dec. 31, 2020 USD ($) item $ / shares	Jun. 30, 2020 USD ($)	Dec. 31, 2019 USD ($) item $ / shares	May 31, 2018 USD ($)	Jun. 30, 2021 USD ($)	Sep. 30, 2021 USD ($)	Dec. 31, 2021 USD ($) item $ / shares	Dec. 31, 2020 USD ($) $ / shares	Dec. 31, 2019 USD ($) item $ / shares	Jan. 31, 2022 USD ($)	Dec. 08, 2021 $ / shares	Nov. 10, 2021 USD ($)	Mar. 31, 2021 USD ($)	Dec. 22, 2020 $ / shares	Jan. 31, 2020	Dec. 31, 2017 USD ($)
Accrued interest				$ 1,500,000						$ 3,800,000	$ 1,500,000		$ 413,000
Deferred finance fees										8,025,000
Loans Payable			$ 215,193,000	197,330,000				$ 215,193,000	$ 223,503,000	$ 219,249,000	197,330,000					$ 207,317,000
Warrants, Exercise Price (in dollars per share) | $ / shares						$ 6.50				$ 4.31		$ 6.50		$ 1.90			$ 4.31
Debt Instrument, Interest Rate, Effective Percentage	7.00%
Repayment of loans and secured line of credit										$ 3,200,000	2,500,000	$ 2,000,000
Secured Debt			8,950,000	$ 7,747,000				8,950,000	11,950,000	12,750,000	7,747,000					$ 8,950,000
Equity Method Investments										4,800,000
Repayment of loans								$ 56,413,000	$ 56,413,000	$ 225,547,000	$ 23,368,000	10,557,000
250 North 10th JV
Equity Method Investment, Ownership Percentage										10.00%								10.00%
Debt Instrument, Face Amount	$ 82,750,000
Sterling National Bank [Member]
Debt Instrument, Interest Rate Terms										200 basis points over the 30-day LIBOR, now bears interest at the prime rate, currently 3.25%.  The secured line of credit
Maximum borrowing capacity										$ 12,750,000
Mezzanine Loan
Accrued interest										1,100,000
Term of the debt				3 years
Loans Payable										30,300,000
Debt Instrument Blended Effective Interest Rate				9.44%
Collateral for loan, equity interests in subsidiaries (as a percent)				100.00%							100.00%
Debt Instrument, Number of Extensions | item				2
Debt Instrument , Extension Term				1 year
Increase in loans including accrued interest		$ 22,770,000
Previously accrued interest		$ 770,000
Debt Instrument, Face Amount				$ 7,500,000							$ 7,500,000
Mezzanine Loan | RCG LV Debt VI REIT LLC [Member]
Debt Instrument, Face Amount							$ 15,400,000
Letter of Credit [Member]
Loans Payable				$ 7,750,000						$ 12,750,000	$ 7,750,000
Debt Instrument, Interest Rate, Effective Percentage				2.14%						3.25%	2.14%
Loans Payable 2018, 237 11th Loans
Delayed draw facility					$ 4,250,000
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, Interest Rate, Increase (Decrease)					25.00%
Exit fee (as a percent)					1.00%
Debt Instrument, Interest Rate, Effective Percentage					2.25%
Debt Instrument Exit Fee Rate, Increase (Decrease)					50.00%
Repayment of loans and secured line of credit			56,400,000
Debt Instrument, Exit Fees			$ 567,000
Debt Instrument, Face Amount							$ 67,800,000
Loans Payable 2018, 237 11th Loans | Minimum
Interest rate basis (as a percent)					50.00%
237 11th Loan
Debt Instrument, Face Amount							$ 52,400,000
Partner Loan
Term of the debt	4 years	1 year
Loans Payable										$ 5,900,000
Debt Instrument, Number of Extensions | item		2
Debt Instrument , Extension Term		12 months
Threshold Maximum Common Stock Price Per Share, To Trigger Prepayment Of Debt Instrument | $ / shares	$ 6.50
Debt Instrument, Face Amount	$ 5,900,000	$ 10,500,000
Interest rate	7.00%	10.00%
Amount available for interest payments		$ 500,000
Amount funded at closing		$ 10,000,000.0
250 North 10th Loan
Term of the debt	15 years
Interest rate	3.39%
New 237 11th Loans
Term of the debt			2 years
Debt Instrument, Number of Extensions | item			3
Debt Instrument , Extension Term			1 year
Proceeds From Debt Reserved To Cover Debt Service, Operating Expense Shortfall And Leasing Related Costs			$ 1,500,000
Interest rate			3.05%					3.05%
New Senior Loan
Initial advance at closing										48,700,000
Debt Instrument, Face Amount			$ 50,000,000.0					$ 50,000,000.0
New Mezzanine Loan
Initial advance at closing										10,000,000.0
Debt Instrument, Face Amount			10,000,000					10,000,000
Interest Rate Cap Agreement New 237 11 Loan
Debt Instrument, Unamortized Premium			32,500					32,500
Derivative, Notional Amount			$ 60,000,000.0					$ 60,000,000.0
Interest rate			2.50%					2.50%
77 Mortgage Loan
Term of the debt		2 years
Loans Payable										125,400,000
Accrued PIK interest										1,800,000
Repayment of loans and secured line of credit										8,900,000
Debt Instrument, Face Amount		$ 133,100,000
Maximum borrowing capacity		166,700,000
Repayment of loans		159,400,000
Proceeds from debt issuance used to fund construction and carry costs while condo units are being sold		33,600,000
Threshold amount of accrued and unpaid PIK interest and additional unused fee		91,000,000.0
Threshold amount for accrual of interests and additional unused fee		$ 4,500,000
Percentage of Additional Unused Fee		1.00%
Additional unused amount		$ 3,000,000.0
Minimum total return for mortgage lender		$ 15,260,000
Percentage of additional amounts advanced		10.00%
77 Mortgage Loan | Letter of credit
Borrower guaranteed amount		$ 4,000,000.0
Borrower guaranteed reduced amount		3,000,000.0
Pay-down amount per square feet of unsold residential units		$ 625
77 Mortgage Loan | Principal balance below $91.0 Million
Interest rate		7.25%
77 Mortgage Loan | Principal balance equal or greater than $91.0 Million
Interest rate		9.25%
77 Mortgage Loan | LIBOR | Principal balance below $91.0 Million
Interest rate basis (as a percent)		7.00%
77 Mortgage Loan | LIBOR | Principal balance equal or greater than $91.0 Million
Interest rate basis (as a percent)		9.00%
Corporate Credit Facility
Increase in maximum borrowing capacity						$ 25,000,000.0						25,000,000.0
Deferred finance fees				$ 3,900,000						2,900,000	$ 3,900,000
Term of the debt						32 months
Loans Payable				$ 35,750,000						$ 35,750,000	$ 35,750,000
Debt Instrument, Interest Rate Terms						a rate per annum equal to the sum of (i) 5.25% and (ii) a scheduled interest rate of 4% (the “Cash Pay Interest Rate”) which increases by 0.125% every six-month period from the Closing Date, subject to increase during the extension periods.
Debt Instrument, Interest Rate, Increase (Decrease)											0.125%
Debt Instrument, Interest Rate, Basis for Effective Rate										9.5%
Commitment fee						$ 2,450,000				$ 1,850,000		$ 2,450,000
Commitment fee, payable on the initial draw (as a percent)										50.00%
Commitment fee, payable on subsequent draws (as a percent)										50.00%
Exit fee (as a percent)										1.00%
Multiple On Invested Capital (as a percent)										30.00%
Collateral for loan, equity interests in subsidiaries (as a percent)										100.00%
Common stock repurchase through proceeds from debt, amount authorized										$ 2,000,000.0
Common stock repurchase through other sources of cash, amount authorized										$ 1,500,000
Threshold minimum loan outstanding (as a percent)										50.00%
Number of board members who can be appointed by the lender | item						1						1
Maximum number of committees of the board, that the Designee can sit | item										3
Reduction in commitments made by CCF										$ 7,500,000
Warrants, Exercise Price (in dollars per share) | $ / shares				$ 6.50						$ 4.31	$ 6.50
Debt amount used to calculate the MOIC															$ 35,750,000
Maximum borrowing capacity						$ 70,000,000.0						$ 70,000,000.0
Corporate Credit Facility | Greenwich Ny 77 [Member]
Net cash proceeds of residential condominium sales (as a percent)										70.00%
Corporate Credit Facility | Minimum
Net cash proceeds of residential condominium sales (as a percent)										90.00%
Corporate Credit Facility | Maximum
Net cash proceeds of residential condominium sales (as a percent)										100.00%
Corporate Credit Facility | PIK Interest Rate
Interest rate basis (as a percent)											5.25%
Corporate Credit Facility | Cash Pay Interest Rate
Interest rate basis (as a percent)											4.00%
Greenwich Construction Loan
Term of the debt										4 years
Loans Payable				$ 139,000,000.0							$ 139,000,000.0
Debt Instrument, Interest Rate, Effective Percentage				9.25%							9.25%
Repayment of loans and secured line of credit										$ 8,000,000.0
Debt Instrument, Face Amount																			$ 189,500,000
Interest rate description										LIBOR plus 8.25% and (ii) 9.25%