Schedule III: Real Estate and Accumulated Depreciation - Schedule (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Encumbrances	$ 996,544
Initial cost of Land	19,206
Initial cost of Building and Leasehold improvements	24,435
Costs capitalized subsequent to acquisition	1,041,556
Carrying amount of Land	32,271
Carrying amount of Buildings and Leasehold improvements	1,046,132
Development and Construction in progress	6,794
Total	1,085,197	$ 1,066,620	$ 1,084,598	$ 1,069,426
Accumulated Depreciation and Amortization	443,627	415,903	$ 396,268	$ 370,557
Net basis difference of assets and liabilities between tax basis and GAAP basis	133,704
Mortgages
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Deferred debt issuance costs, net	8,525	$ 3,993
Rego Park I
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Encumbrances	0
Initial cost of Land	1,647
Initial cost of Building and Leasehold improvements	8,953
Costs capitalized subsequent to acquisition	92,868
Carrying amount of Land	1,647
Carrying amount of Buildings and Leasehold improvements	100,327
Development and Construction in progress	1,494
Total	103,468
Accumulated Depreciation and Amortization	$ 49,616
Date of Construction	1959
Date acquired	1992
Rego Park I | Minimum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	3 years
Rego Park I | Maximum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	39 years
Rego Park II
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Encumbrances	$ 202,544
Initial cost of Land	3,127
Initial cost of Building and Leasehold improvements	1,467
Costs capitalized subsequent to acquisition	403,946
Carrying amount of Land	3,127
Carrying amount of Buildings and Leasehold improvements	400,113
Development and Construction in progress	5,300
Total	408,540
Accumulated Depreciation and Amortization	$ 146,937
Date of Construction	2009
Date acquired	1992
Rego Park II | Minimum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	3 years
Rego Park II | Maximum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	40 years
The Alexander apartment tower
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Encumbrances	$ 94,000
Initial cost of Land	0
Initial cost of Building and Leasehold improvements	0
Costs capitalized subsequent to acquisition	115,091
Carrying amount of Land	0
Carrying amount of Buildings and Leasehold improvements	115,091
Development and Construction in progress	0
Total	115,091
Accumulated Depreciation and Amortization	$ 30,283
Date of Construction	2016
Date acquired	1992
The Alexander apartment tower | Minimum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	3 years
The Alexander apartment tower | Maximum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	39 years
Flushing
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Encumbrances	$ 0
Initial cost of Land	0
Initial cost of Building and Leasehold improvements	1,660
Costs capitalized subsequent to acquisition	(107)
Carrying amount of Land	0
Carrying amount of Buildings and Leasehold improvements	1,553
Development and Construction in progress	0
Total	1,553
Accumulated Depreciation and Amortization	$ 1,383
Date of Construction	1975
Date acquired	1992
Lexington Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Encumbrances	$ 700,000
Initial cost of Land	14,432
Initial cost of Building and Leasehold improvements	12,355
Costs capitalized subsequent to acquisition	429,758
Carrying amount of Land	27,497
Carrying amount of Buildings and Leasehold improvements	429,048
Development and Construction in progress	0
Total	456,545
Accumulated Depreciation and Amortization	$ 215,408
Date of Construction	2003
Date acquired	1992
Lexington Avenue | Minimum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	9 years
Lexington Avenue | Maximum
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation
Life on which Depreciation in Latest Income Statement is Computed	39 years