Real Estate and Accumulated Depreciation - Schedule III (Summary of Real Estate Investments) (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	$ 399,500
Land	193,658
Building and Improvements	504,536
Costs Capitalized Subsequent to Acquisition	71,092
Gross amount carried	769,286	$ 765,176	$ 762,519	$ 759,487
Accumulated depreciation	131,467	112,641	$ 92,470	$ 72,656
Acquired intangible assets	71,848	$ 87,478
Tax basis	743,700
Accumulated amortization	(36,500)
421 W. 54th Street - Hit Factory
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	0
Land	4,723
Building and Improvements	1,757
Costs Capitalized Subsequent to Acquisition	(1,443)
Gross amount carried	5,037
Accumulated depreciation	370
400 E. 67th Street - Laurel Condominiums
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	44,610
Land	10,653
Building and Improvements	55,682
Costs Capitalized Subsequent to Acquisition	86
Gross amount carried	66,421
Accumulated depreciation	11,668
200 Riverside Blvd - ICON Garage
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	5,390
Land	13,787
Building and Improvements	5,510
Costs Capitalized Subsequent to Acquisition	0
Gross amount carried	19,297
Accumulated depreciation	1,136
9 Times Square
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	49,500
Land	54,153
Building and Improvements	76,454
Costs Capitalized Subsequent to Acquisition	26,746
Gross amount carried	157,353
Accumulated depreciation	33,926
123 William Street
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	140,000
Land	50,064
Building and Improvements	182,917
Costs Capitalized Subsequent to Acquisition	36,343
Gross amount carried	269,324
Accumulated depreciation	53,800
Mortgage note payable — 1140 Avenue of the Americas
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	99,000
Land	0
Building and Improvements	148,647
Costs Capitalized Subsequent to Acquisition	8,251
Gross amount carried	156,898
Accumulated depreciation	27,517
8713 Fifth Avenue
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	10,000
Land	4,730
Building and Improvements	9,245
Costs Capitalized Subsequent to Acquisition	1,109
Gross amount carried	15,084
Accumulated depreciation	972
196 Orchard Street
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Encumbrances	51,000
Land	55,548
Building and Improvements	24,324
Costs Capitalized Subsequent to Acquisition	0
Gross amount carried	79,872
Accumulated depreciation	$ 2,078
Building
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Useful life	40 years
Land Improvements
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Useful life	15 years
Minimum | Furniture and Fixtures
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Useful life	5 years
Maximum | Furniture and Fixtures
SEC Schedule, 12-28, Real Estate Companies, Investment in Real Estate and Accumulated Depreciation [Line Items]
Useful life	7 years