Loans Payable and Secured Line of Credit - Additional Information (Details)		1 Months Ended						3 Months Ended
	Jan. 15, 2020 USD ($)	Feb. 28, 2023 USD ($)	Jan. 31, 2023 USD ($)	Oct. 31, 2021 USD ($)	Jun. 30, 2021 USD ($)	Dec. 31, 2020 USD ($) item $ / shares	Dec. 31, 2019 USD ($)	Mar. 31, 2023 USD ($) item $ / shares	Apr. 30, 2023	Apr. 27, 2023	Apr. 21, 2023 USD ($) item	Dec. 31, 2022 USD ($)	Nov. 30, 2022 USD ($)	Mar. 31, 2022	Dec. 22, 2020 $ / shares	Nov. 30, 2020 $ / shares	Oct. 31, 2017 USD ($)
Loans Payable and Secured Line of Credit
Long-term debt, gross								$ 247,725,000
Deferred finance fees								2,405,000
Loans payable, net								$ 198,894,000				$ 208,762,000
Warrants, exercise price (in dollars per share) | $ / shares								$ 4.31							$ 4.50
Repayment of notes payable								$ 5,863,000
Proceeds from secured line of credit								$ 2,000,000
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								$ 7,000,000.0
Term of the debt						3 years
Loans payable, net								$ 30,300,000
Debt instrument blended effective interest rate								10.30%
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
Proceeds from debt reserved to cover debt service					$ 1,500,000
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
Principal amount					$ 50,000,000.0
237 11th Mezz Loan
Loans Payable and Secured Line of Credit
Loans payable, net								10,000,000.0				10,000,000.0
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								110,000,000.0
Repayment of loans and secured line of credit								$ 58,200,000
All-in interest rate percentage								11.50%
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								$ 4,500,000
Debt modification, gain (loss)								0
Debt, maximum loan balance, option to extend								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 | LIBOR | Principal balance below $91.0 Million
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)				7.00%
77 Mortgage Loan | LIBOR | Principal balance equal or greater than $91.0 Million
Loans Payable and Secured Line of Credit
Interest rate basis (as a percent)				9.00%
Corporate Credit Facility
Loans Payable and Secured Line of Credit
Increase in maximum borrowing capacity							$ 25,000,000.0
Long-term debt, gross								35,750,000				35,750,000
Deferred finance fees								1,100,000				1,300,000
Accrued interest								$ 6,700,000				$ 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								10.00%				10.00%
Commitment fee							$ 2,450,000	$ 1,850,000
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%
Threshold minimum loan outstanding (as a percent)								50.00%
Number of board members who can be appointed by the lender | item								1
Maximum number of committees of the board, that the Designee can sit | item								3
Reduction in commitments under CCF						$ 7,500,000
Warrants, exercise price (in dollars per share) | $ / shares						$ 4.31										$ 6.50
Debt amount used to calculate the MOIC								$ 35,750,000
Maximum borrowing capacity							$ 70,000,000.0
Debt modification, gain (loss)								0
Prepayment amount due on or prior to May 1, 2023								$ 7,000,000.0
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%
Corporate Credit Facility | Minimum
Loans Payable and Secured Line of Credit
Net cash proceeds of residential condominium sales (as a percent)								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%
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%
Corporate Credit Facility | Subsequent Event
Loans Payable and Secured Line of Credit
Maximum number of committees of the board, that the Designee can sit | item											3
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%
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
Interest rate (as a percent)										2.50%
Secured Line of Credit
Loans Payable and Secured Line of Credit
Loans payable, net								$ 11,750,000				$ 9,750,000
Debt Instrument interest rate effective percentage								7.75%				7.50%
Maximum borrowing capacity								$ 11,750,000
Debt modification, gain (loss)								$ 0
Secured Line of Credit | Subsequent Event
Loans Payable and Secured Line of Credit
Interest rate (as a percent)									2.50%	2.50%