Loans Payable and Secured Line of Credit - Additional Information (Details)		1 Months Ended									3 Months Ended	6 Months Ended
	Jan. 15, 2020 USD ($)	Jul. 31, 2023	Jun. 30, 2023 USD ($) item $ / shares shares	Apr. 30, 2023 USD ($) item	Feb. 28, 2023 USD ($)	Jan. 31, 2023 USD ($)	Oct. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($) item $ / shares	Dec. 31, 2019 USD ($)	Jun. 30, 2023 USD ($) item $ / shares	Jun. 30, 2023 USD ($) item $ / shares	May 01, 2023 USD ($)	Apr. 27, 2023	Dec. 31, 2022 USD ($)	Nov. 30, 2022 USD ($)	Dec. 22, 2020 $ / shares	Nov. 30, 2020 $ / shares	Oct. 31, 2017 USD ($)
Loans Payable and Secured Line of Credit
Long-term debt, gross			$ 246,728,000								$ 246,728,000	$ 246,728,000
Deferred finance fees			1,509,000								1,509,000	1,509,000
Loans payable, net			$ 195,547,000								$ 195,547,000	$ 195,547,000			$ 208,762,000
Warrants, exercise price (in dollars per share) | $ / shares			$ 4.31								$ 4.31	$ 4.31					$ 4.50
Repayment of notes payable												$ 5,863,000
Principal amount	$ 5,900,000
Temporary certificate of occupancy, percentage												100.00%
250 North 10th JV
Loans Payable and Secured Line of Credit
Equity method investment, ownership percentage			10.00%								10.00%	10.00%
Mezzanine Loan
Loans Payable and Secured Line of Credit
Accrued interest			$ 8,400,000								$ 8,400,000	$ 8,400,000
Term of the debt									3 years
Loans payable, net			30,300,000								30,300,000	$ 30,300,000
Debt instrument blended effective interest rate												12.05%
Collateral for loan, equity interests in subsidiaries (as a percent)									100.00%
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
Principal amount									$ 7,500,000
Partner Loan
Loans Payable and Secured Line of Credit
Term of the debt	4 years
Repayment of notes payable					$ 5,900,000
Interest rate (as a percent)	7.00%
Principal amount	$ 5,900,000
250 North 10th Loan
Loans Payable and Secured Line of Credit
Term of the debt	15 years
Interest rate (as a percent)	3.39%
Principal amount	$ 82,750,000
237 11th Loans
Loans Payable and Secured Line of Credit
Term of the debt								2 years
Debt instrument blended effective interest rate												5.35%
Number of extensions | item												3
Debt instrument extension term								1 year
Interest rate (as a percent)								3.05%
Debt modification, gain (loss)												$ 0
237 11th Senior Loan
Loans Payable and Secured Line of Credit
Loans payable, net			50,000,000.0								50,000,000.0	50,000,000.0			50,000,000.0
Principal amount								$ 50,000,000.0
237 11th Mezz Loan
Loans Payable and Secured Line of Credit
Term of the debt								2 years
Loans payable, net			10,000,000.0								10,000,000.0	10,000,000.0			10,000,000.0
Debt instrument extension term								1 year
Principal amount								$ 10,000,000
Interest Rate Cap Agreement New 237 11 Loan
Loans Payable and Secured Line of Credit
Debt instrument, unamortized premium								32,500
Derivative, notional amount								$ 60,000,000.0
Interest rate (as a percent)								2.50%
77 Mortgage Loan
Loans Payable and Secured Line of Credit
Term of the debt							2 years
Loans payable, net			$ 106,000,000.0								$ 106,000,000.0	106,000,000.0
Repayment of loans and secured line of credit												$ 62,100,000
All-in interest rate percentage			12.05%								12.05%	12.05%
Maximum borrowing capacity																			$ 166,700,000
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%
Principal amount							$ 133,100,000
Amount drawn under letter of credit to fund an interest reserve																$ 3,000,000.0
Amount drawn under letter of credit to pay down the PIK balance																$ 1,000,000.0
Accrued PIK interest			$ 4,400,000								$ 4,400,000	$ 4,400,000
Debt modification, gain (loss)												0
Debt, maximum loan balance, option to extend			70,000,000.0								70,000,000.0	70,000,000.0
77 Mortgage Loan | Principal balance below $91.0 Million
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)							7.25%
77 Mortgage Loan | Principal balance equal or greater than $91.0 Million
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)							9.25%
77 Mortgage Loan | Minimum
Loans Payable and Secured Line of Credit
Anticipated loan balance			70,000,000.0								70,000,000.0	70,000,000.0
77 Mortgage Loan | SOFR | Principal balance below $91.0 Million
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)							7.00%
77 Mortgage Loan | SOFR | Principal balance equal or greater than $91.0 Million
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)							9.00%
Subsequent Event | 237 11th Loans
Loans Payable and Secured Line of Credit
Debt instrument extension term		1 year
Corporate Credit Facility
Loans Payable and Secured Line of Credit
Increase in maximum borrowing capacity			5,000,000							$ 25,000,000.0	5,000,000	5,000,000
Long-term debt, gross			38,750,000								38,750,000	38,750,000			35,750,000
Deferred finance fees			828,000								828,000	828,000			1,300,000
Accrued interest			$ 7,800,000								$ 7,800,000	$ 7,800,000			$ 6,100,000
Interest paid						$ 419,000
Term of the debt										32 months
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												0.125%
Debt Instrument interest rate effective percentage			10.325%								10.325%	10.325%			10.00%
Commitment fee			$ 1,850,000							$ 2,450,000	$ 1,850,000	$ 1,850,000
Commitment fee, payable on the initial draw (as a percent)			50.00%								50.00%	50.00%
Commitment fee, payable on subsequent draws (as a percent)			50.00%								50.00%	50.00%
Exit fee (as a percent)			1.00%								1.00%	1.00%
Multiple On Invested Capital (as a percent)			30.00%								30.00%	30.00%
Collateral for loan, equity interests in subsidiaries (as a percent)			100.00%								100.00%	100.00%
Threshold minimum loan outstanding (as a percent)			50.00%								50.00%	50.00%
Number of board members who can be appointed by the lender | item			1								1	1
Maximum number of committees of the board, that the Designee can sit | item			3	3							3	3
Reduction in commitments under CCF									$ 7,500,000
Debt amendment, minimum percentage held by lender of the sum of the aggregate principal amount of advances outstanding and aggregate unused commitments to determine if lender is granted the right to appoint an independent director to the Company's Board of Directors				50.00%
Warrants, exercise price (in dollars per share) | $ / shares									$ 4.31									$ 6.50
Principal amount of debt deferred				$ 7,000,000.0
Amount of the debt to be prepaid by a specified date if no strategic transaction is entered into				$ 5,000,000.0
Debt amount used to calculate the MOIC			$ 35,750,000								$ 35,750,000	$ 35,750,000
Interest rate (as a percent)														2.50%
Maximum borrowing capacity										$ 70,000,000.0
Debt modification, gain (loss)											0	0
Prepayment amount due on or prior to May 1, 2023													$ 7,000,000.0
Amount used for general corporate purpose			$ 3,000,000								$ 3,000,000	$ 3,000,000
Interest rate increase			0.20%
Common stock issued | shares			750,000
Debt amendment, automatic renewal period				30 days
Debt amendment, renewal period upon approval of the Lender				30 days
Amount of the debt to be prepaid by a specified date if strategic transaction is entered into				$ 5,000,000
Corporate Credit Facility | Greenwich NY 77
Loans Payable and Secured Line of Credit
Net cash proceeds of residential condominium sales (as a percent)			70.00%								70.00%	70.00%
Corporate Credit Facility | Minimum
Loans Payable and Secured Line of Credit
Net cash proceeds of residential condominium sales (as a percent)			90.00%								90.00%	90.00%
Corporate Credit Facility | Maximum
Loans Payable and Secured Line of Credit
Net cash proceeds of residential condominium sales (as a percent)			100.00%								100.00%	100.00%
Amount to be used for extension of loans			$ 2,000,000								$ 2,000,000	$ 2,000,000
Corporate Credit Facility | PIK Interest Rate
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)												5.25%
Corporate Credit Facility | Cash Pay Interest Rate
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)												4.00%
Secured Line of Credit
Loans Payable and Secured Line of Credit
Loans payable, net			$ 11,750,000								$ 11,750,000	$ 11,750,000			$ 9,750,000
Debt Instrument interest rate effective percentage			2.50%								2.50%	2.50%			7.50%
Interest rate (as a percent)				2.50%
Maximum borrowing capacity			$ 11,750,000								$ 11,750,000	$ 11,750,000
Debt modification, gain (loss)												$ 0