Note 5 - Notes Payable - Mortgages and Mezzanine Note Payable (Details) - USD ($) $ in Thousands		9 Months Ended
		Sep. 30, 2023	Dec. 31, 2022
Debt, gross		$ 1,211,856
Unamortized debt issuance costs		(14,578)	$ (9,650)
Debt, gross		1,197,278	1,161,588
Mortgages and Mezzanine Notes 1[Member]
Debt, gross		1,211,856	1,171,238
Unamortized debt issuance costs		$ (14,578)	(9,650)
Mortgages and Mezzanine Notes 1[Member] | Flatbush Gardens, Brooklyn, NY [Member]
Interest Rate	[1]	3.125%
Debt, gross	[1]	$ 329,000	329,000
Mortgages and Mezzanine Notes 1[Member] | 250 Livingston Street in Brooklyn [Member]
Interest Rate	[2]	3.63%
Debt, gross	[2]	$ 125,000	125,000
Mortgages and Mezzanine Notes 1[Member] | 141 Livingston Street, Brooklyn [Member]
Interest Rate	[3]	3.21%
Debt, gross	[3]	$ 100,000	100,000
Mortgages and Mezzanine Notes 1[Member] | Tribeca House Properties [Member]
Interest Rate	[4]	4.506%
Debt, gross	[4]	$ 360,000	360,000
Mortgages and Mezzanine Notes 1[Member] | Aspen [Member]
Interest Rate	[5]	3.68%
Debt, gross	[5]	$ 61,399	62,554
Mortgages and Mezzanine Notes 1[Member] | Clover House [Member]
Interest Rate	[6]	3.53%
Debt, gross	[6]	$ 82,000	82,000
Mortgages and Mezzanine Notes 1[Member] | Property at 10 W 65th St. Manhattan, NY [Member]
Debt, gross	[7]	$ 31,929
Mortgages and Mezzanine Notes 1[Member] | Property at 10 W 65th St. Manhattan, NY [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt, gross	[7]		32,222
Debt Instrument, Basis Spread on Variable Rate	[7]	2.50%
Mortgages and Mezzanine Notes 1[Member] | Residential Property At 1010 Pacific Street [Member]
Debt, gross	[8]	$ 0
Mortgages and Mezzanine Notes 1[Member] | Residential Property At 1010 Pacific Street [Member] | London Interbank Offered Rate [Member]
Debt, gross	[8]		43,477
Debt Instrument, Basis Spread on Variable Rate	[8]	3.60%
Mortgages and Mezzanine Notes 1[Member] | Dean Street, Prospect Heights [Member]
Debt, gross	[9]	$ 0
Mortgages and Mezzanine Notes 1[Member] | Dean Street, Prospect Heights [Member] | Prime Rate [Member]
Debt, gross	[9]		36,985
Debt Instrument, Basis Spread on Variable Rate	[9]	1.60%
Mortgages and Mezzanine Notes 2 [Member] | Residential Property At 1010 Pacific Street [Member]
Interest Rate	[8]	5.55%
Debt, gross	[8]	$ 60,000	0
Mortgages and Mezzanine Notes 2 [Member] | Dean Street, Prospect Heights [Member]
Debt, gross	[9]	$ 37,899	0
Mortgages and Mezzanine Notes 2 [Member] | Dean Street, Prospect Heights [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Debt Instrument, Basis Spread on Variable Rate	[9]	4.00%
Mortgages and Mezzanine Notes 3[Member] | Residential Property At 1010 Pacific Street [Member]
Interest Rate	[8]	6.37%
Debt, gross	[8]	$ 20,000	0
Mortgages and Mezzanine Notes 3[Member] | Dean Street, Prospect Heights [Member]
Debt, gross	[9]	$ 4,629	$ 0
Mortgages and Mezzanine Notes 3[Member] | Dean Street, Prospect Heights [Member] | Secured Overnight Financing Rate (SOFR) Overnight Index Swap Rate [Member]
Interest Rate	[9]	10.00%

[1] The $329,000 mortgage note agreement with New York Community Bank (“NYCB”), entered into on May 8, 2020, matures on June 1, 2032, and bears interest at 3.125% through May 2027 and thereafter at the prime rate plus 2.75%, subject to an option to fix the rate. The note requires interest-only payments through May 2027, and monthly principal and interest payments thereafter based on a 30-year amortization schedule. The Company has the option to prepay all (but not less than all) of the unpaid balance of the note prior to the maturity date, subject to certain prepayment premiums, as defined.

[2] The $125,000 mortgage note agreement with Citi Real Estate Funding Inc., entered into on May 31, 2019, matures on June 6, 2029, bears interest at 3.63% and requires interest-only payments for the entire term. The Company has the option to prepay all (but not less than all) of the unpaid balance of the note within three months of maturity, without a prepayment premium.

[3] The $100,000 mortgage note agreement with Citi Real Estate Funding Inc., entered into on February 18, 2021 matures on March 6, 2031, bears interest at 3.21% and requires interest-only payments for the entire term. The Company has the option to prepay all (but not less than all) of the unpaid balance of the note within three months of maturity, without a prepayment premium.

[4] The $360,000 loan with Deutsche Bank, entered into on February 21, 2018, matures on March 6, 2028, bears interest at 4.506% and requires interest-only payments for the entire term. The Company has the option to prepay all (but not less than all) of the unpaid balance of the loan prior to the maturity date, subject to a prepayment premium if it occurs prior to December 6, 2027.

[5] The $70,000 mortgage note agreement with Capital One Multifamily Finance LLC matures on July 1, 2028, and bears interest at 3.68%. The note required interest-only payments through July 2017, and monthly principal and interest payments of $321 thereafter based on a 30-year amortization schedule. The Company has the option to prepay the note prior to the maturity date, subject to a prepayment premium.

[6] The $82,000 mortgage note agreement with MetLife Investment Management, entered into on November 8, 2019, matures on December 1, 2029, bears interest at 3.53% and requires interest-only payments for the entire term. The Company has the option, commencing on January 1, 2024, to prepay the note prior to the maturity date, subject to a prepayment premium if it occurs prior to September 2, 2029.

[7] The $32,200 mortgage note agreement with NYCB entered into in connection with the acquisition of the property matures on November 1, 2027. Through October 2022 the Company paid a fixed interest rate of 3.375% and thereafter was scheduled to pay interest at the prime rate plus 2.75%, subject to an option to fix the rate. On August 26, 2022, the Company and NYCB amended the note to replace prime plus 2.75% rate with SOFR plus 2.5% (7.875% at September 30, 2023). The note required interest-only payments through November 2019, and monthly principal and interest payments thereafter based on a 30-year amortization schedule. The Company has the option to prepay all (but not less than all) of the unpaid balance of the note prior to the maturity date, subject to certain prepayment premiums, as defined.

[8] On December 24, 2019, the Company entered into a $18,600 mortgage note agreement with CIT Bank, N.A., related to the 1010 Pacific Street acquisition. The Company also entered into a pre-development bridge loan secured by the property with the same lender to provide up to $2,987 for eligible pre-development and carrying costs. The notes were scheduled to mature on June 24, 2021, required interest-only payments and bore interest at one-month LIBOR (with a floor of 1.25%) plus 3.60%. The notes were extended in June 2021 with a new maturity date of August 30, 2021. The Company guaranteed this mortgage note and complied with the financial covenants therein.

[9] On December 22, 2021, the Company entered into a $30,000 mortgage note agreement with Bank Leumi, N.A related to the Dean Street acquisition. The notes original maturity was December 22, 2022 and was subsequently extended to September 22, 2023. The note required interest-only payments and bears interest at the prime rate (with a floor of 3.25%) plus 1.60% (9.85% as of June 30, 2023). In April 2022, the Company borrowed an additional $6,985 under the mortgage note in connection with the acquisition of additional parcels of land in February and April 2022.